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May 3, 2005

https://www.sciencedaily.com/releases/2005/05/050503153444.htm

Rock Hounds Sleuth Rise Of Earth's Atmosphere

Washington, D.C. -- "CSI-like" techniques, used on minerals, are revealing the steps that led to evolution of the atmosphere on Earth. President of the Mineralogical Society of America, Douglas Rumble, III, of the Carnegie Institution's Geophysical Laboratory, describes the suite of techniques and studies over the last five years that have led to a growing consensus by the scientific community of what happened to produce the protective ozone layer and atmosphere on our planet. His landmark paper on the subject appears in the May/June American Mineralogist.

"Rocks, fossils, and other natural relics hold clues to ancient environments in the form of different ratios of isotopes--atomic variants of elements with the same number of protons but different numbers of neutrons," explained Rumble. "Seawater, rain water, oxygen, and ozone, for instance, all have different ratios, or fingerprints, of the oxygen isotopes 16O, 17O, and 18O. Weathering, ground water, and direct deposition of atmospheric aerosols change the ratios of the isotopes in a rock revealing a lot about the past climate." Rumble's paper describes how geochemists, mineralogists, and petrologists are studying anomalies of isotopes of oxygen and sulfur to piece together what happened to our atmosphere from about 3.9 billion years ago, when the crust of our planet was just forming and there was no oxygen in the atmosphere, to a primitive oxygenated world 2.3 billion years ago, and then to the present. The detective work involves a pantheon of scientists who have analyzed surface minerals from all over the globe, used rockets and balloons to sample the stratosphere, collected and studied ice cores from Antarctica, conducted lab experiments, and run mathematical models. The synthesis from the different fields and techniques points to ultraviolet (UV) light from the Sun as an important driving force in atmospheric evolution. Solar UV photons break up molecular oxygen (O2) to produced ozone (O3) leaving a tell-tale isotopic signature of excess 17O. The ozone layer began to form as the atmosphere gained oxygen, and has since shielded our planet from harmful solar rays and made life possible on Earth's surface. The discovery of isotope anomalies, where none were previously suspected, adds a new tool to research on the relationships between shifts in atmospheric chemistry and climate change. Detailed studies of polar-ice cores and exposed deposits in Antarctic dry valleys may improve our understanding of the history of the ozone hole.

Ozone Holes

May 2, 2005

https://www.sciencedaily.com/releases/2005/05/050502093904.htm

Solar Storms, Arctic Winds Swirl In A Double Dip Cone Of Ozone Loss

Solar storms, such as the unusually intense events in October and November 2003, affect many aspects of our lives, such as radio signals and satellite communications. Now a new study partially funded by NASA and using data from several NASA instruments has shown that those late 2003 solar storms, which deposited huge quantities of energetic solar particles into Earth's atmosphere, combined forces with another natural atmospheric process last spring to produce the largest decline ever recorded in upper stratospheric ozone over the Arctic and the northern areas of North America, Europe and Asia.

A form of oxygen, ozone protects life on Earth from harmful ultraviolet radiation. The ozone layer has thinned markedly in the high latitudes of the Northern and Southern Hemispheres in recent decades, primarily due to chemical reactions with chlorofluorocarbons and other industrial gases from human activities in the lower stratosphere, about 15 to 20 kilometers (9 to 12 miles) in altitude. Such ozone loss normally occurs only during very cold Arctic winters.Last spring, however, following a warm Arctic winter, scientists were surprised to see record levels of ozone loss in the upper, not lower, stratosphere; reductions in ozone levels of up to 60 percent about 40 kilometers (25 miles) above Earth's high northern latitudes. This unusual ozone destruction resulted from processes distinctly different from the more commonly observed lower stratospheric ozone loss caused by chemical reactions with chlorofluorocarbons. This time the culprits were high levels of nitrogen oxide and nitrogen dioxide, two gases that together destroy stratospheric ozone. An international team of scientists from the United States, Canada and Europe, including researchers from NASA's Jet Propulsion Laboratory, Pasadena, Calif., and Langley Research Center, Hampton, Va., set out to uncover the processes behind the unexpected ozone loss.Using data from seven satellites, including NASA's Stratospheric Aerosol and Gas Experiment II and III instruments on the Earth Radiation Budget Satellite and the Halogen Occultation Experiment on NASA's Upper Atmospheric Research Satellite, the researchers concluded the record ozone declines were the result of a combination of unusual stratospheric weather conditions and energetic solar particles in the atmosphere resulting from the vigorous solar storm activity. Results of the study appear in the online version of the American Geophysical Union journal Geophysical Research Letters."The 2003-2004 Arctic winter was unique," said Dr. Gloria Manney, a JPL atmospheric scientist and one of the paper's co-authors. "First, the stratospheric polar vortex, a massive low-pressure system that confines air over the Arctic, broke down in a major stratospheric warming that lasted from January to February 2004. Such midwinter warmings typically last only a few days to a week. Then, in February and March 2004, winds in the upper stratospheric polar vortex sped up to their strongest levels on record. The vortex allowed the nitrogen gases, which are believed to have formed at least 10 kilometers (6 miles) above the stratosphere as a result of chemical reactions triggered by energetic solar particles, to descend more easily than normal into the stratosphere."Study lead author Dr. Cora Randall of the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics said the phenomenon illustrates the difficulties in separating ozone-destroying atmospheric effects resulting from natural versus human-induced causes. "These findings point out a critical need to better understand the processes occurring in the ozone layer, and demonstrate that scientists searching for signs of ozone recovery need to factor in the atmospheric effects of energetic particles, something they do not now do," she said.Scientists believe the 1987 Montreal Protocol, an international agreement that phased out production and use of ozone-destroying compounds, may allow the protective ozone layer to recover by the middle of this century. NASA's Aura spacecraft is providing insights into physical and chemical processes that influence the health of the stratospheric ozone layer and climate, producing the most complete suite of chemical measurements ever made.Manney, lead author of another new paper on Arctic stratospheric interannual variability appearing in the Journal of Geophysical Research, said the findings underscore the incredible complexity of the Arctic region and why more research is necessary."While the 2004-2005 Arctic winter has been unusually cold, six of the past seven Arctic winters were unusually warm, with little or no potential for Arctic chemical ozone loss," she said. "This period of warm winters was immediately preceded by a period of unusually cold winters. The point is that it is absolutely critical that we understand how and why the Arctic stratosphere varies from year to year, and that we need to be very careful to consider and account for natural variability when determining trends in atmospheric circulation, temperature, ozone levels and climate change."

Ozone Holes

March 14, 2005

https://www.sciencedaily.com/releases/2005/03/050309105438.htm

Huge 2004 Stratospheric Ozone Loss Tied To Solar Storms, Arctic Winds

A new study led by the University of Colorado at Boulder indicates that two natural atmospheric processes in 2004 caused the largest decline in upper stratospheric ozone ever recorded over the far Northern Hemisphere.

According to Research Associate Cora Randall of CU-Boulder's Laboratory for Atmospheric and Space Physics, nitrogen oxide and nitrogen dioxide gases in the upper stratosphere climbed to the highest levels in at least two decades in spring 2004. The increases led to ozone reductions of up to 60 percent roughly 25 miles in altitude above Earth's high northern latitudes, said Randall."This decline was completely unexpected," she said. "The findings point out a critical need to better understand the processes occurring in the ozone layer." Randall is chief author of a paper on the subject appearing in the March 2 online issue of Geophysical Research Letters, published by the American Geophysical Union.Randall worked with an international team of scientists from the United States, Canada and Europe to look at data from seven different satellites, concluding both the sun and stratospheric weather were responsible for the ozone declines.Winds in the upper part of a massive winter low-pressure system that confines air over the Arctic region, known as the polar stratospheric vortex, sped up in February and March 2004 to become the strongest on record, she said. The spinning vortex allowed the nitrogen gases, believed by the team to have formed at least 20 miles above the stratosphere as a result of chemical reactions triggered by energetic particles from the sun, to descend more easily into the stratosphere.The increases in the two nitrogen gases -- collectively known as NOx -- are important because they are major players in the stratospheric ozone destruction process, said Randall. The team concluded that some of the extra NOx seen in the springtime was actually formed after huge quantities of energetic particles from the sun bombarded Earth's atmosphere during the Halloween solar storms of 2003."No one predicted the dramatic loss of ozone in the upper stratosphere of the northern hemisphere in the spring of 2004," she said. "That we can still be surprised illustrates the difficulties in separating atmospheric effects due to natural and human-induced causes."This study demonstrates that scientists searching for signs of ozone recovery need to factor in the atmospheric effects of energetic particles, something they do not now do."The 2004 enhancements of NOx gases in the upper stratosphere and subsequent ozone losses occurred over the Arctic and the northern areas of North America, Europe and Asia, said the paper authors. Severe ozone losses also can occur during winter and spring in the stratosphere at about 12 miles in altitude, driven primarily by very cold temperatures, they said.Because of seasonal conditions, the researchers are unable to measure the precise contributions of solar storms and stratospheric weather to the NOx spike seen in the stratosphere last year. "No observations of upper atmospheric nitrogen gases are available in the polar region in the winter, so the descending NOx cannot be traced to its origin," said Randall.A form of oxygen, ozone protects life on Earth from the harmful effects of ultraviolet radiation. The ozone layer has thinned markedly in high latitudes of the Northern and Southern Hemispheres in recent decades, primarily due to reactions involving chlorofluorocarbons and other industrial gases.Scientists believe the 1987 Montreal Protocol, an international agreement that has phased out the production and use of such ozone-destroying compounds, may allow the protective ozone layer to be restored by the middle of this century.The research team used data from satellite instruments, including POAM II, POAM III, SAGE II, SAGE III, HALOE, MIPAS and OSIRIS for the study.###Co-authors on the paper include researchers from CU-Boulder, the National Oceanic and Atmospheric Administration, NASA, the Harvard-Smithsonian Center for Astrophysics in Cambridge, Hampton University and GATS Inc. of Hampton, Va., York University in Toronto, Chalmers University of Technology in Sweden and the Norwegian Institute for Air Research.

Ozone Holes

March 1, 2005

https://www.sciencedaily.com/releases/2005/02/050223130549.htm

Global Warming Led To Atmospheric Hydrogen Sulfide And Permian Extinction

Washington, D.C. -– Volcanic eruptions in Siberia 251 million years ago may have started a cascade of events leading to high hydrogen sulfide levels in the oceans and atmosphere and precipitating the largest mass extinction in Earth’s history, according to a Penn State geoscientist.

"The recent dating of the Siberian trap volcanoes to be contemporaneous with the end-Permian extinction suggests that they were the trigger for the environmental events that caused the extinctions," says Lee R. Kump, professor of geosciences. "But the warming caused by these volcanoes through carbon dioxide emissions would not be large enough to cause mass extinctions by itself."That warming, however, could set off a series of events that led to mass extinction. During the end-Permian extinction 95 percent of all species on Earth became extinct, compared to only 75 percent during the K-T when a large asteroid apparently caused the dinosaurs to disappear.Volcanic carbon dioxide would cause atmospheric warming that would, in turn, warm surface ocean water. Normally, the deep ocean gets its oxygen from the atmosphere at the poles. Cold water there soaks up oxygen from the air and because cold water is dense, it sinks and slowly moves equator-ward, taking oxygen with it. The warmer the water, the less oxygen can dissolve and the slower the water sinks and moves toward the equator.“Warmer water slows the conveyer belt and brings less oxygen to the deep oceans,” says Kump.The constant rain of organic debris produced by marine plants and animals, needs oxygen to decompose. With less oxygen, fewer organics are aerobically consumed."Today, there are not enough organics in the oceans to go anoxic," says Kump. "But in the Permian, if the warming from the volcanic carbon dioxide decreased oceanic oxygen, especially if atmospheric oxygen levels were lower, the oceans would be depleted of oxygen."Once the oxygen is gone, the oceans become the realm of bacteria that obtain their oxygen from sulfur oxide compounds. These bacteria strip oxygen from the compounds and produce hydrogen sulfide. Hydrogen sulfide kills aerobic organisms.Humans can smell hydrogen sulfide gas, the smell of rotten cabbage, in the parts per trillion range. In the deeps of the Black Sea today, hydrogen sulfide exists at about 200 parts per million. This is a toxic brew in which any aerobic, oxygen-needing organism would die. For the Black Sea, the hydrogen sulfide stays in the depths because our rich oxygen atmosphere mixes in the top layer of water and controls the diffusion of hydrogen sulfide upwards.In the end-Permian, as the levels of atmospheric oxygen fell and the levels of hydrogen sulfide and carbon dioxide rose, the upper levels of the oceans could have become rich in hydrogen sulfide catastrophically. This would kill most the oceanic plants and animals. The hydrogen sulfide dispersing in the atmosphere would kill most terrestrial life."A hydrogen sulfide atmosphere fits the extinction better than one enriched in carbon dioxide," says Kump. "Carbon dioxide would have a profound effect on marine life, but terrestrial plants thrive on carbon dioxide, yet they are included in the extinction."Another piece in the puzzle surrounding this extinction is that hydrogen sulfide gas destroys the ozone layer. Recently, Dr. Henk Visscher of Utrecht University and his colleagues suggested that there are fossil spores from the end-Permian that show deformities that researchers suspect were caused by ultra violet light."These deformities fit the idea that the ozone layer was damaged, letting in more ultra violet," says Kump.Once this process is underway, methane produced in the ample swamps of this time period has little in the atmosphere to destroy it. The atmosphere becomes one of hydrogen sulfide, methane and ultra violet radiation.The Penn State researcher and his colleagues are looking for biomarkers, indications of photosynthetic sulfur bacteria in deep-sea sediments to complement such biomarkers recently reported in shallow water sediments of this age by Kliti Grice, Curtin University of Technology, Australia, and colleagues in the Feb. 4 issue of the journal, Science. These bacteria live in places where no oxygen exists, but there is some sunlight. They would have been in their heyday in the end-Permian. Finding evidence of green sulfur bacteria would provide evidence for hydrogen sulfide as the cause of the mass extinctions.

Ozone Holes

March 1, 2005

https://www.sciencedaily.com/releases/2005/02/050222113953.htm

Scientists Advance In Detection And Attribution Of Climate Change

WASHINGTON, D.C. — Access to the next generation of climate change experiments has helped scientists obtain more comprehensive estimates of the expected “signal” of human influences on climate.

Improved knowledge of this signal, and a better understanding of uncertainties in temperature observations, have helped to advance “detection and attribution” (“D&A”) studies, which assist in unraveling the causes of recent climate change."The climate system is telling us an internally consistent story,” said Ben Santer, an atmospheric scientist at Lawrence Livermore National Laboratory. “We’ve observed warming of the Earth’s land surface and oceans, cooling of the stratosphere, an increase in height of the tropopause, retreat of Arctic sea ice, and widespread melting of glaciers. These changes are difficult to reconcile with purely natural causes.”Santer reports today on the identification of human influences on recent atmospheric temperature changes during a climate change session at the American Association for the Advancement of Science annual meeting in Washington, D.C. The title of the panel is “Detection and Attribution – Methods and Results – of Climate Trends in Temperature Sensors, Species and Glaciers.”Santer works in Livermore’s Program for Climate Model Diagnosis and Intercomparison (PCMDI), and has compared new computer model simulations performed at several different research institutes to observational records of recent temperature change. The climate models analyzed by Santer and colleagues included changes in both manmade forcings (well-mixed greenhouse gases, tropospheric and stratospheric ozone, and the scattering effects of sulfate aerosols) and natural external forcings (solar irradiance and volcanic aerosols).Earlier Livermore research has determined that human-induced changes in ozone and well-mixed greenhouse gases are the primary drivers of recent changes in the height of the tropopause – the boundary between the turbulently mixed troposphere and the more stable stratosphere. Research with new model and observational datasets strengthens these findings.“With new model experiments coming online, we’re now in a much better position to estimate how climate changed in response to combined human and natural influences,” Santer said.PCMDI is archiving data from recently completed experiments performed with coupled ocean-atmosphere general circulation models that took place at more than a dozen research institutes worldwide. “This data will be a very valuable resource for the Laboratory and the whole community,” Santer said. “We are sitting on a real scientific goldmine.”Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and to apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

Ozone Holes

February 25, 2005

https://www.sciencedaily.com/releases/2005/02/050223153440.htm

Warming World Could Worsen Pollution In Northeast, Midwest

CAMBRIDGE, Mass. -- While science's conventional wisdom holds that pollution feeds global warming, new research suggests that the reverse could also occur: A warming globe could stifle summer's cleansing winds over the Northeast and Midwest over the next 50 years, significantly worsening air pollution in these regions.

Loretta J. Mickley, a research associate at Harvard University's Division of Engineering and Applied Sciences, will report on these findings Saturday, Feb. 19, at the annual meeting of the American Association for the Advancement of Science in Washington, D.C. Her work is based on modeling of the impact of increasing greenhouse gas concentrations on pollution events across the United States through 2050.Using this model, Mickley and colleagues found that the frequency of cold fronts bringing cool, clear air out of Canada during summer months declined about 20 percent. These cold fronts, Mickley said, are responsible for breaking up hot, stagnant air that builds up regularly in summer, generating high levels of ground-level ozone pollution."The air just cooks," Mickley says. "The pollution accumulates, accumulates, accumulates, until a cold front comes in and the winds sweep it away."Ozone is beneficial when found high in the atmosphere because it absorbs cancer-causing ultraviolet radiation. Near the ground, however, high concentrations are considered a pollutant, irritating sensitive tissues, particularly lung tissues."If this model is correct, global warming would cause an increase in difficult days for those affected by ozone pollution, such as people suffering with respiratory illnesses like asthma and those doing physical labor or exercising outdoors," Mickley says.Mickley and her colleagues used a complex computer model developed by the Goddard Institute for Space Studies in New York, with further changes devised by her team at Harvard. It takes known elements such as the sun's luminosity, the earth's topography, the distribution of the oceans, the pull of gravity and the tilt of the earth's axis, and figures in variables provided by researchers.Mickley gradually increased levels of greenhouse gases at rates projected by the Intergovernmental Panel on Climate Change, a group charged by the United Nations to study future climate variation. Her model looked at the effect the changing climate would have on the concentrations of two pollutants: black carbon particles -- essentially soot -- and carbon monoxide, which could also indicate ozone levels. When the model first indicated that future climate change would lead to higher pollution in the Northeast and Midwest, Mickley and her colleagues were a bit surprised."The answer lies in one of the basic forces that drive the Earth's weather: the temperature difference between the hot equator and the cold poles," Mickley says.Between those extremes, the atmosphere acts as a heat distribution system, moving warmth from the equator toward the poles. Over mid-latitudes, low-pressure systems and accompanying cold fronts are one way for heat to be redistributed. These systems carry warm air poleward ahead of fronts and draw down cooler air behind fronts.In the future, that process could slow down. As the globe warms, the poles are expected to warm more quickly than the equator, decreasing the temperature difference between the poles and the equator. The atmosphere would then have less heat to redistribute and would generate fewer low-pressure systems.With fewer cold fronts sweeping south to break up hot stagnant air over cities, the air would sit in place, gathering pollutants. Mickley's model shows the length of these pollution episodes would increase significantly, even doubling in some locations.Mickley's collaborators include Daniel J. Jacob and B. D. Field at Harvard and D. Rind of the Goddard Institute for Space Studies.###Their work was funded by a Science to Achieve Results (STAR) grant from the Environmental Protection Agency.

Ozone Holes

February 8, 2005

https://www.sciencedaily.com/releases/2005/02/050205122519.htm

Temple Researcher Attempting To Create Cyclic Ozone

With nearly twice the energy of normal, bent-shaped ozone (O3), cyclic ozone could hold the key component for a future manned-mission to Mars. No one has ever seen-let alone made-cyclic ozone. But that could all change at Temple University's Center for Advanced Photonics Research, which has been awarded a one-year, $1.25 million grant to develop cyclic ozone by the Defense Advanced Research Projects Administration (DARPA).

The research is being carried out under the guidance of Center Director Robert J. Levis, Ph.D., a pioneer in strong field, laser-based chemistry and adaptive photonics. Strong field chemistry uses ultrafast lasers to produce intense laser pulses that create tremendous electric fields around a molecule. This forms-for a brief instant in time-a new molecule that chemically can react in new and unexpected ways. Levis and his group began pioneering this revolutionary technology about a decade ago."The formation of cyclic ozone is a high-risk project," concedes Levis. "No one has ever taken ozone and made the free cyclic form, where every oxygen atom is bound to every other oxygen atom, making it look like an equilateral triangle."Nobody knows exactly what the molecule looks like spectroscopically or how to make it," he adds. "And that's exactly the type of high-risk, high-payoff problem that our laser-based technologies can figure out."Levis points out that the successful production of cyclic ozone could play an important role in putting a human on Mars because rockets could be able to carry one-third more payload."The bent form of ozone carries about one-and-a-half volts of energy, while cycle ozone carries about three volts," says Levis. "So there's no more mass, but you can get much more energy when the cyclic ozone combines with hydrogen and is burned."This is way-over-the-horizon research," he adds. "But if you can produce cyclic ozone, that might be a key component to interplanetary space exploration."Because cyclic ozone has never before been characterized, Levis and the Temple researchers-Dmitri Romanov of physics and Spiridoula Matsika of chemistry-are relying exclusively on an evolutionary search strategy theory to help them synthesize the molecule using ultrafast lasers. Researchers from the chemistry and chemical engineering departments at Princeton University and the mathematics department at Yale University have been subcontracted by Levis to assist in the development of the search theory.The Center for Advanced Photonics Research (www.temple.edu/capr) is focused on developing new science and technologies through intense laser-molecule interactions. The center has three of the most powerful laser systems on the East Coast each with a laser pulse shaping capabilities. Research ranges from probing fundamental physics principles to detecting chemical warfare agents."One of the aspects that DARPA finds fascinating is that these shaped reagents have what's called a massive 'search space,'" says Levis. "The 'search space' is huge, something like 1040 (ten to the fortieth power) possibilities, more than the number of stars in the universe. There are an incredible number of paths we can take to find cyclic ozone and we have to search through them somehow."Levis equates the size of the search space to the variability in the human genome, composed of four distinct bases strung in a genome containing roughly three billion bases."That's four to the three billionth different ways you can arrange those four bases," he says. "And yet, humans have evolved into an extremely complex organism."The question is how did this organization occur, and Levis answers by saying that evolution, or Mother Nature, has an excellent search strategy. "What we've managed to do here at the center is take that evolutionary search strategy and put it into an experimental, chemical situation," he says. "It's an experimentalist's dream. We have a target molecule that's never been made before, and we're going to try to make it with technology that is right on the horizon, and we're going to detect it relying on calculations that are state-of-the-art."Levis says his team, which also includes chemist Herschel Rabitz and chemical engineer Yannis Kevrekidis from Princeton and mathematician Raphy Coiffman from Yale, will be making only a small amount of cyclic ozone, since his laser-rigs would not be capable of mass-producing it."This laser system will only produce micro-grams, which won't power the Space Shuttle," he says. "But once we've made even a little, other scientists and chemical engineers can study it, learn more about the potential energy surface and chemical reactivity, and possibly find a way to reverse engineer a catalyst to produce it in mass quantities."

Ozone Holes

February 3, 2005

https://www.sciencedaily.com/releases/2005/01/050128214057.htm

Scientists Studying Wintry Ice In Summer Clouds

Winter is here, snow is falling in many areas of the country, and some of us are already wishing for the return of hot summer days. But, would you believe that even on the hottest summer day the temperature inside some clouds remains icy and winter-like, producing temperature readings as cold as negative 70 degrees Celsius (negative 94 degrees Fahrenheit)? Would you also believe that the ice crystals that form at the top of big summertime clouds may help scientists predict next winter's snowstorm?

Last month, scientists from NASA's Langley Research Center in Hampton, Va. and Goddard Space Flight Center in Greenbelt, Md. published a paper in the Journal of Geophysical Research on the importance of classifying ice crystals within the big summertime clouds, or convective cloud systems, as observed during a Florida-based research campaign. In their paper, the scientists showed that their instruments can identify the ice crystals and now they can begin to classify the crystals. By learning to classify the ice crystals in clouds, these scientists hope to contribute to improving weather and climate models, the complex computer programs used to show future atmospheric conditions.Weather and climate computer models are complex because they must account for hundreds of variables, including many that seem completely unpredictable. Vincent Noel, a research scientist with Analytical Services and Materials at NASA Langley and the author of the journal article, explains, "Usually climate prediction means predicting the evolution of temperature, pressure, relative humidity, and plenty of other variables, over small (a few days) and large (a few centuries) timeframes. However, to predict all this stuff with enough accuracy, we need to take into account clouds -- and for the time being, clouds are the most important source of uncertainty in climate prediction."Recognizing that clouds represent so much scientific uncertainty, some NASA scientists and other researchers decided to study tropical convective clouds in Florida, a type of large cloud system very common in that area. Their research project, called CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment), took place in the summer of 2002 throughout the state of Florida and the Gulf of Mexico, with the immediate goal of studying all aspects of the unique convection cloud formations from aircraft, land and satellite-based instruments.If you have spent a day at Disney World in Orlando, or if you have relaxed on the beaches of South Florida, you have likely seen convective or heat-generated clouds. These clouds form when the Sun's rays warm the ground, causing hot air to rise, and condense into clouds. They are unique because they are massive in size, at times ranging from 100 to 200 km wide (62 to 124 miles); they form and dissipate very quickly, in as little as two hours; and they can be extremely thick, reaching 15 km (9.3 miles) in height, which is 6 km (3.7 miles) taller than Mt. Everest.At the top of the convective clouds are cirrus clouds made of ice crystals. These crystals effect weather and climate in two ways: first, depending on the ice crystal's shape, it affects the amount of Sun's energy reflected or trapped near Earth's surface; and second, in their relationship with ozone destruction in the upper atmosphere (stratosphere)."Because of all this solar radiation, the Earth gets hot," said Noel. "When any body is hot, it radiates infrared light." Infrared is light at one end of the spectrum, and people use infrared goggles to see things in the dark (which is how you can see people in the dark using infrared goggles). "Clouds trap this infrared radiation, absorb it, and re-emit it later; this is called the greenhouse effect." Clouds, specifically cirrus clouds, are the reason that a lot of infrared radiation stays near Earth instead of going into space.Because of their high altitude, ice clouds touch the tropopause, the region between the troposphere (the atmospheric layer closest to Earth) and the stratosphere. When the rising air on a summer day is hot enough, it can move fast enough where it "punches through" the tropopause and into the stratosphere. This "overshooting cloud top" brings water vapor into that layer of the upper atmosphere, where it contributes to destroying the "good ozone" that protects us from the Sun's harmful ultraviolet (UV) radiation.Then the ozone reacts with the UV radiation, and creates oxygen again. This cycle results in less UV radiation getting to Earth. Unfortunately, water can also react with ozone, thus destroying the ozone faster than it is created. "So, if there's too much stratospheric water, the creation/destruction cycle of ozone is affected," said Noel.The size, shape and composition of the ice crystals may reveal a lot about their effects on these atmospheric processes. "The ice crystal shapes are infinite and varied. We don't know which shapes are dominant, a problem when trying to predict climate change because the shape influences the quantity of sunlight reflected back into space," said Noel.The scientists used short pulses of laser light known as Lidar, to classify ice crystals. They compared Lidar measurements from high-flying aircraft (up to approximately 20 km, or 12.4 miles) with measurements from other instruments. In the future, they hope to use satellite data to get the information, instead of flying airplanes.One upcoming long-term study that will use a space-based instrument is the CALIPSO satellite mission (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations). CALIPSO is scheduled to be launched in June 2005, and will give us new, never-before-seen 3-D perspectives of how clouds and aerosols form, evolve and affect Earth's weather, climate and air quality.###+ CRYSTAL-FACE Mission Web Site: + CALIPSO Mission Web Site:

Ozone Holes

January 31, 2005

https://www.sciencedaily.com/releases/2005/01/050128214344.htm

International Science Team Measures Arctic's Atmosphere

An international team of scientists embarked this week on a journey to improve modeling of global-scale air quality and climate change predictions by conducting high quality measurements of the Arctic region's atmosphere.

The Polar Aura Validation Experiment (PAVE) will gather information to validate data from NASA's Aura satellite, launched in July 2004. PAVE is the third in a series of planned Aura validation and science missions. These missions will help understand the transport and transformation of gases and aerosols in the lower atmosphere (troposphere), and their exchange with those in the lower stratosphere, the layer just above the troposphere. PAVE takes place from Jan. 24 to Feb. 9."In addition to providing important validation for the various Aura data products, PAVE brings together a full NASA complement of space-based and suborbital measurements to study the atmospheric chemistry and transport of gases and aerosols in this sensitive region of our planet," said Dr. Michael Kurylo, Program Scientist for PAVE, at NASA Headquarters in Washington. "The information from this campaign will aid in understanding how changing atmospheric composition, associated with climate change, might affect the recovery of the Earth's ozone layer that is anticipated to occur over the next several decades," he said.In particular, PAVE focuses on the Arctic region of the Northern Hemisphere, where winter chemistry has led to significant seasonal reduction of the stratospheric ozone layer in many years, over more than a decade. The ozone layer restricts the amount of the sun's ultraviolet radiation that reaches the Earth. Depletion of this protective layer can have harmful effects on humans and other ecosystems.NASA's DC-8 flying laboratory and high-altitude balloons are collecting valuable science data, especially on ozone and ozone-destroying chemicals, using a suite of atmospheric remote sensing and "in situ" instruments. The aircraft, operated by NASA's Dryden Flight Research Center, Edwards, Calif., is flying the PAVE mission from Pease International Tradeport, Portsmouth, N.H. Balloons are being launched from the European Sounding Rocket Range (ESRANGE) facility in Sweden.The study is focusing on obtaining in situ and remote sensing measurements of the arctic region for validation of the Aura satellite. Information gathered during PAVE will be combined with data from Aura to improve modeling of global-scale air quality, ozone and climate change predictions.Instruments on board the DC-8 are characterizing upper tropospheric and stratospheric gases inside and outside the Arctic polar region to study ozone depletion chemistry. Such flights also permit measurement of the outflow of gases from the North American continent, thereby contributing to an understanding of how regional pollutants are distributed in the hemisphere.Scientists will make remote sensing measurements (extending many kilometers away from the aircraft) of tropospheric and stratospheric ozone, aerosols, temperature, nitric acid, HCl, ClO and other ozone-related chemicals. These are complemented by measurements of components such as ozone, methane, water vapor, carbon monoxide, nitric acid and nitrous oxide, in the atmosphere immediately surrounding the aircraft.Major PAVE partners include the University of New Hampshire, Durham; University of California-Berkeley; University of Bremen, Germany; National Center for Atmospheric Research (NCAR), Boulder, Colo.; the U.S. Naval Research Laboratory in Washington; Koninklijk Netherlands Meteorological Institute; and Los Gatos Research, Inc., Mountain View, Calif.For more information about the Aura mission on the Internet, visit:

Ozone Holes

December 31, 2004

https://www.sciencedaily.com/releases/2004/12/041219212232.htm

NASA's ICESat Satellite Sees Changing World Affecting Many

The Earth is a dynamic entity, and scientists are trying to understand it. Various things in nature grow and shrink, such as ice sheets, glaciers, forests, rivers, clouds and atmospheric pollutants, serving as the pulse of the planet and affecting many people in many walks of life. Scientists using NASA's Ice, Cloud, and land Elevation Satellite (ICESat) are measuring the height of these dynamic features from space with unprecedented accuracy, providing a new way of understanding our changing planet. ICESat has lasers onboard that help it make the most accurate measurements ever.

Because ICESat's unique instruments enable it to see changes in elevation, one of the areas scientists focus on are changes in the ice at the poles and in glaciers around the world. As the ICESat satellite circles the world, it sees changes in the heights of ice at the poles, and the movement of glaciers whether melting or building with snow and ice.Recently ICESat confirmed accelerated movement of glaciers in the Antarctic Peninsula, following the breakup of the floating ice shelf into which the glaciers flowed. ICESat also confirmed that part of the West Antarctic ice sheet has been the increasingly getting thinner. By knowing all of these changes in snow and ice, scientists have a better idea of how melting areas affect the rise of sea level.Picture a polar bear on an icy surfboard. ICESat is also measuring the height of "Sea Ice Freeboards," or ice and snow that are floating above the ocean's surface, to an average between 12 to 16 inches (30 to 40 centimeters). Imagine being able to determine how thick an "icy surfboard" is by only a foot. Watching the changes in the thickness of sea ice is necessary for reliably forecasting the possible disappearance of the Arctic sea ice pack during the summertime months.In winter 2004, ICESat showed thicker sea ice grouped together in its usual place near the Canadian Arctic than it was in 2003. ICESat also showed a larger area of thinner ice in the Beaufort and Chukchi Seas where the summer ice cover has been rapidly decreasing. The location and amount of ice is important to climatologists and also ships that travel those seas.Everyone knows what a cloud looks like, but scientists need to know what percentage of clouds cover the Earth everyday, in order to make their computer climate models and weather forecast computer models work better. ICESat has provided the most accurate figure to date, and tells us that 70 percent of the world is cloud covered. Previous estimates ranged from 50 to 75 percent.ICESat has also allowed scientists to see in 3-D the clouds that form in the upper atmosphere near the poles, called "polar stratospheric clouds." These clouds are responsible for the formation of the "ozone holes" over the poles where a break down the protective ozone layer in the stratosphere occurs in the spring.The layer of the atmosphere below the stratosphere is called the troposphere. The troposphere can be divided into two parts, a planetary boundary layer, PBL, extending upward from the ground to a few thousand feet high, and a "free atmosphere" that lies above it. ICESat provided the first global estimation of the top of the PBL. Since the PBL is where heat and moisture from the surface is held, its height is an important new observation for computer models that predict climate and weather. It's also the place where pollution gets trapped down at the surface where we live. Some places we know it as smog on the ground.Pollution affects everyone. Over the whole world the small particles in man made haze are now known to be an important factor causing the climate to change. We now have the first global measurement from ICESat of the height distribution of these tiny particles of pollution.Campers, land managers, and computer climate modelers have some things in common. They all wonder about how high a forest grows, the height of mountains and depth of valleys, and the height of rivers and lakes. ICESat is helping to answer all those questions."ICESat is making unprecedented measurements of the height of forests from space," said David Harding, of NASA's Goddard Space Flight Center in Greenbelt, Md. Traditional satellite images tell us about how far a forest extends, but not the height of the top, or canopy of a forest. Scientists are interested in knowing that, because it clues them into how much carbon is absorbed in trees. That's important because carbon dioxide is a key greenhouse gas that traps heat in the lower atmosphere and warms the Earth. ICESat's forest top measurements are accurate down to one meter (3.2 feet).In addition to vegetation or forest height, ICESat also provides very precise measurements of land elevations. ICESat's data is being combined with data from the Shuttle Radar Topography Mission (SRTM), a joint mission by NASA, JPL, and the Department of Defense flown in 2000, to create the most accurate global topographic data available for the Earth.In the face of growing worldwide populations, monitoring and managing global water resources are becoming increasingly important. ICESat can measure the changing height of inland water bodies, including rivers, lakes, reservoirs and wetlands. These measurements can even be made of water surfaces even where they are covered by vegetation, such as in flooded forests of the Amazon.ICESat's new data, collected around the globe in 2003 and 2004, has given scientists the ability to see the way many things around the Earth change, from the polar ice sheets and oceans to rainforests.

Ozone Holes

December 22, 2004

https://www.sciencedaily.com/releases/2004/12/041217101919.htm

NASA's Aura Satellite Sheds New Light On Air Quality And Ozone Hole

NASA scientists announced the agency's Aura spacecraft is providing the first daily, direct global measurements of low-level ozone and many other pollutants affecting air quality.

For the first time, Aura will help scientists monitor global pollution production and transport with unprecedented spatial resolution. Aura's measurements offer new insights into how climate changes influence the recovery of the Earth's protective stratospheric ozone layer."Data from NASA missions like Aura are a valuable national asset," said Aura Program Scientist Phil DeCola of NASA Headquarters, Washington. "Clean air is a vital need, and air quality is not merely a local issue. Pollutants do not respect state or national boundaries. They can degrade air quality far from their sources. Aura's view from space enables us to understand the long-range transport of pollutants," he added."Aura's early results are nothing short of astounding; measurements like these will help us better understand how the ozone hole will react to future stratospheric cooling, which is expected as carbon dioxide levels continue to rise," said Aura Project Scientist Mark Schoeberl of NASA's Goddard Space Flight Center, Greenbelt, Md.Aura's instruments study tropospheric chemistry and will provide daily, global monitoring of air pollution. The complexity of pollution transport makes it difficult to quantify how much industry and cars contribute to poor local air quality. Also, the presence of stratospheric ozone sandwiched between the satellite and the troposphere makes seeing tropospheric ozone very difficult. Aura's Tropospheric Emission Spectrometer (TES) uses new technology to see through the stratospheric ozone layer, to measure tropospheric ozone.Aura also provides new insights into the physical and chemical processes that influence the health of the stratospheric ozone layer and climate. It's producing the most complete suite of chemical measurements ever available to understand the ozone layer and its recovery.Data will include the first measurements of chemically reactive hydrogen-containing species involved in ozone destruction. The satellite also will provide the first simultaneous measurements of key forms of chlorine and bromine, also important for ozone destruction. Aura measures the upper-tropospheric water-vapor abundance, a key component in the radiation budget, needed to understand climate change.Launched July 15, 2004, Aura is the third and final major Earth Observing System satellite. Aura's view of the atmosphere and its chemistry will complement the global data already being collected by NASA's other Earth Observing System satellites. These projects are Terra, primarily focused on land, and Aqua, which comprehensively observes Earth's water cycle. Collectively, these satellites allow scientists to study the complexities of how land, water and our atmosphere work as a system.Aura carries four instruments: Ozone Monitoring Instrument (OMI), Microwave Limb Sounder (MLS), High Resolution Dynamics Limb Sounder (HIRDLS) and the Tropospheric Emission Spectrometer (TES). OMI was built by the Netherlands and Finland in collaboration with NASA. HIRDLS was built by the United Kingdom and the United States.The information was released during the American Geophysical Union Fall meeting in San Francisco.For information related to this story on the Internet, visit:

Ozone Holes

December 17, 2004

https://www.sciencedaily.com/releases/2004/12/041217100237.htm

Giant Atmospheric Brown Cloud Has Intercontinental Reach

NASA scientists announced a giant, smoggy atmospheric brown cloud, which forms over South Asia and the Indian Ocean, has intercontinental reach. The scientists presented their findings today during the American Geophysical Union Fall meeting in San Francisco.

The scientists discussed the massive cloud's sources, global movement and its implications. The brown cloud is a moving, persistent air mass characterized by a mixed-particle haze. It also contains other pollution, such as ozone."Ozone is a triple-threat player in the global environment. There are three very different ways ozone affects our lives," said Robert Chatfield, a scientist at NASA's Ames Research Center, Moffett Field, Calif. "A protective layer of good ozone, high in the atmosphere, shields us from deadly ultraviolet light that comes from the sun. Second, bad or smog ozone near the surface of Earth can burn our lungs and damage crops. In our study, we are looking at a third major effect of ozone, that it can warm the planet, because it is a powerful greenhouse gas," Chatfield said."We found both brown cloud pollution and natural processes can contribute to unhealthy levels of ozone in the troposphere where we live and breathe. Some ozone from the brown cloud rises to high enough altitudes to spread over the global atmosphere," Chatfield explained. Ozone from the Earth's protective stratospheric layer, produced by natural processes, can migrate down to contribute to concentrations in the lower atmosphere, according to the scientists.The researchers studied the intercontinental smog ozone processes associated with the brown cloud over South Asia. They used a NASA technique that combines data acquired by satellites with ozone data measured by instruments on special weather balloons.The ozone-monitoring instrument on NASA's Aura satellite is providing data about the brown cloud. "The beautiful, high-detail images from this instrument promise to help us sort out our major questions about how much of the tropospheric ozone is from pollution and how much is from natural factors," Chatfield said.Analysis shows ozone in the lower atmosphere over the Indian Ocean comes from the intensely developed industrial-agricultural areas in the region. The southern pollutant buildup has long-range effects, often traveling across Africa, further than the brown cloud of particles, according to researchers.To access technical information about the brown cloud study on the Web, visit:

Ozone Holes

December 15, 2004

https://www.sciencedaily.com/releases/2004/12/041208230905.htm

Columbia Team Shows How Stratospheric Conditions Affect Weather

Three members of Columbia’s Department of Applied Physics and Applied Mathematics have used a simple climate model to demonstrate how the weather systems and storms we experience may be influenced by disturbances in the Earth’s stratosphere, the upper layer of atmosphere between 10 and 30 miles high. This Earth Institute research was recently highlighted by the American Geophysical Union, following recent publication in the journal Geophysical Research Letters.

“Our research shows that changes to the strength of winds in the stratosphere cause changes to tropospheric weather systems” explained lead-author Matthew Wittman.Understanding how the stratosphere affects the troposphere, the lowermost layer of the atmosphere where weather occurs, is important to improving seasonal weather forecasts and predicting the effect of ozone depletion and global warming on our climate.“The stratosphere has a longer ‘memory’ than the troposphere,” adds co-author Andrew Charlton. “If you want to make forecasts on a time scale longer than several days, it is useful to understand the mechanisms linking places with longer memories, such as the stratosphere and the oceans to the troposphere.”Each winter a westerly jet — called the Polar Night Jet — forms in the stratosphere. Winds in this jet circulate around the pole at speeds of up to 100 miles per hour. The strength of this jet changes as part of normal atmospheric variability, and possibly also in response to climate change. In their new research, the authors show that the presence of stronger westerly jets in the stratosphere causes tropospheric weather systems to track further towards the pole.Averaging the changes to the paths of weather systems, the research team showed, produces a pattern of changes similar in structure to the Arctic Oscillation, the dominant pattern of climate variability in the Northern Hemisphere that describes how temperatures across the whole hemisphere vary together.The research is part of the team’s ongoing efforts to understand the interaction of the stratosphere and troposphere and improve the representation of this interaction in climate models. The Columbia co-authors — Matthew Wittman, Lorenzo Polvani, Richard Scott and Andrew Charlton — are affiliated with the climate research group at the Earth Institute at Columbia.The Earth Institute at Columbia University is the world’s leading academic center for the integrated study of Earth, its environment and society. The Earth Institute builds upon excellence in the core disciplines — earth sciences, biological sciences, engineering sciences, social sciences and health sciences — and stresses cross-disciplinary approaches to complex problems. Through research, training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world’s poor. For more information, visit

Ozone Holes

November 23, 2004

https://www.sciencedaily.com/releases/2004/11/041122100820.htm

Trace Gases Are Key To Halting Global Warming

New York -- Researchers suggest that reductions of trace gases may allow stabilization of climate so that additional global warming would be less than 1° C, a level needed to maintain global coastlines. Although carbon dioxide emissions, an inherent product of fossil fuel use, must also be slowed, the required carbon dioxide reduction is much more feasible if trace gases decrease.

In the current edition of Proceedings of the National Academy of Sciences, Drs. James Hansen and Makiko Sato of NASA's Goddard Institute for Space Studies (GISS) at the Earth Institute at Columbia University suggest that avoidance of large climate change requires the global community to consider aggressive reductions in the emissions of both carbon dioxide and non-carbon dioxide gases called trace gases. Humans have already increased the amount of carbon dioxide in the air from 280 parts per million (ppm) to 380 ppm. If the world continues on its current trajectory of increasing carbon dioxide, methane and ozone, the likely result will be large climate change, with sea level rise of a few meters or more.Hansen and Sato point out that if methane and other trace gases are reduced, climate could be stabilized, with warming less than 1°C, at carbon dioxide levels of 520 ppm. However, if the trace gases continue to increase, carbon dioxide would have to be kept beneath 440 ppm. A cap of 440 ppm seems practically impossible to stay under due to existing energy infrastructure. However, Hansen and Sato suggest that, with the possibility of new technologies by mid-century, it is feasible to keep carbon dioxide levels from exceeding approximately 520 ppm.The co-authors suggest that the non-CO2 gases could be addressed via a Montreal Protocol-like process, or by adding additional gases to the Montreal Protocol itself. The Montreal Protocol has been very effective in reducing emissions of gases that destroy stratospheric ozone. Developed and developing countries have worked together harmoniously in this process, with the World Bank providing support for participation of developing countries."Carbon dioxide is the main greenhouse gas (GHG), and slowdown of its emissions must have priority. It will be a growing issue in international relations for decades, if not longer," says Dr. Hansen. "However, that does not necessarily mean that 'Kyoto' is the best way to address the trace gases. 'Kyoto' gives too little or no weight to gases such as methane, the trace gas HFC-134a, ozone and the precursor gases that form ozone. We could get moving now on non-carbon dioxide gases with benefits such as improved human health, in addition to a slowing of global warming. The resulting international good will might also make discussions about carbon dioxide more productive.""The slowdown in the growth rate of the GHGs contribution to global warming from the peak in the 1980s is due mainly to the phase out of CFCs as dictated by the Montreal Protocol. This success could be diminished by increases of other trace gases not controlled by the Montreal Protocol. We argue that it is well worth extending the Montreal Protocol machinery to phase out many of these trace gases," added Sato.Additionally, the co-authors warn that trace gases also influence the rate at which major atmospheric GHGs are sequestered, a primary strategy for curbing global warming from carbon dioxide emissions. As global warming proceeds, the Earth naturally releases carbon dioxide, methane and nitrous oxide. Therefore, another benefit of reducing trace gases and their warming effect is a reduction of the induced 'natural' releases of these gases. Other bonuses of reducing warming agents such as ozone and soot are improvements in human health and agricultural productivity.NASA provided funding for this study, and the NOAA Climate Monitoring and Diagnostics Laboratory provided access to current measurements of GHGs.

Ozone Holes

November 17, 2004

https://www.sciencedaily.com/releases/2004/11/041116215122.htm

Ground-Level Ozone Linked To Increased Mortality

Changes in ground-level ozone were significantly associated with an increase in deaths in many U.S. cities, according to a nationwide study conducted by researchers at the Johns Hopkins Bloomberg School of Public Health and the Yale University School of Forestry and Environmental Studies. The risk of death was similar for adults of all ages and slightly higher for people with respiratory or cardiovascular problems. The increase in deaths occurred at ozone levels below the Environmental Protection Agency (EPA) clean air standards. The study appears in the November 17, 2004, edition of the Journal of the American Medical Association (JAMA.)

Ground-level ozone is a pollutant in the Earth's lower atmosphere that is formed when emissions from cars, power plants and other sources react chemically to sunlight. Stratospheric ozone, which is higher in the atmosphere, is the “ozone layer” that protects the Earth from ultraviolet radiation.“This is one of the largest ozone pollution studies ever conducted,” said lead author Michelle Bell, PhD, who was previously with the Bloomberg School of Public Health and is now an assistant professor at the Yale School of Forestry and Environmental Studies. The ozone study was part of the ongoing National Morbidity Mortality and Air Pollution Study (NMMAPS) at the Bloomberg School of Public Health, which routinely assesses health effects of air pollution on a national scale. To determine the association between ozone and mortality, the researchers looked at the total number of non-injury-related deaths and cardiovascular and respiratory mortality in the 95 largest U.S. communities from 1987 to 2000. Air pollution data were supplied by the EPA. Mortality data were supplied by the National Center of Health Statistics. The researchers accounted for variables such as weather, particulate matter pollution and seasonality, which could impact mortality rates.The researchers found that an increase of 10 parts per billion (ppb) in weekly ozone levels was associated with a 0.52 percent daily increase in deaths the following week. The rate of daily cardiovascular and respiratory deaths increased 0.64 percent with each 10 ppb increase of weekly ozone. The average daily ozone level for the cities surveyed was 26 ppb. The EPA’s maximum for ground-level ozone over an 8-hour period is 80 ppb. The researchers calculated that a 10 ppb reduction in daily ozone, which is roughly 35 percent of the average daily ozone level, could save nearly 4,000 lives throughout the 95 urban communities included in the study.“Our study shows that ground-level ozone is a national problem, which is not limited to a small number of cities or one region. Everyone needs to be aware of the potential health risks of ozone pollution,” said Francesca Dominici, PhD, senior author of the study and associate professor in the Department of Biostatistics at the Bloomberg School of Public Health.The data and statistical models used to complete the study are available on the Health and Air Pollution Surveillance System website at www.ihapss.jhsph.edu. The site is maintained by the Johns Hopkins Bloomberg School of Public Health and sponsored by the Health Effects Institute.“Ozone and Short-Term Mortality in 95 U.S. Urban Communities, 1987-2000” was written by Michelle L. Bell, PhD; Aidan McDermott, PhD; Scott L. Zeger, PhD; Jonathan M. Samet, MD; and Francesca Dominici, PhD.Funding was provided by grants from the U.S. Environmental Protection Agency, the National Institutes for Environmental Health Sciences, NIEHS Center for Urban Environmental Health and the Health Effects Institute.

Ozone Holes

October 8, 2004

https://www.sciencedaily.com/releases/2004/10/041007064320.htm

Study Shows Potential For Antarctic Climate Change

While Antarctica has mostly cooled over the last 30 years, the trend is likely to rapidly reverse, according to a computer model study by NASA researchers. The study indicates the South Polar Region is expected to warm during the next 50 years.

Findings from the study, conducted by researchers Drew Shindell and Gavin Schmidt of NASA's Goddard Institute of Space Studies (GISS), New York, appeared in the Geophysical Research Letters. Shindell and Schmidt found depleted ozone levels and greenhouse gases are contributing to cooler South Pole temperatures. Low ozone levels in the stratosphere and increasing greenhouse gases promote a positive phase of a shifting atmospheric climate pattern in the Southern Hemisphere, called the Southern Annular Mode (SAM). A positive SAM isolates colder air in the Antarctic interior. In the coming decades, ozone levels are expected to recover due to international treaties that banned ozone-depleting chemicals. Higher ozone in the stratosphere protects Earth's surface from harmful ultraviolet radiation. The study found higher ozone levels might have a reverse impact on the SAM, promoting a warming, negative phase. In this way, the effects of ozone and greenhouse gases on the SAM may cancel each other out in the future. This could nullify the SAM's affects and cause Antarctica to warm. "Antarctica has been cooling, and one could argue some regions could escape warming, but this study finds this is not very likely," Shindell said. "Global warming is expected to dominate in future trends." The SAM, similar to the Arctic Oscillation or Northern Annular Mode in the Northern Hemisphere, is a seesaw in atmospheric pressure between the pole and the lower latitudes over the Southern Ocean and the tip of South America. These pressure shifts between positive and negative phases speed-up and slow down the westerly winds that encircle Antarctica. Since the late 1960s, the SAM has more and more favored its positive phase, leading to stronger westerly winds. These stronger westerly winds act as a kind of wall that isolates cold Antarctic air from warmer air in the lower latitudes, which leads to cooler temperatures. Greenhouse gases and ozone depletion both lower temperatures in the high latitude stratosphere. The cooling strengthens the stratospheric whirling of westerly winds, which in turn influences the westerly winds in the lower atmosphere. According to the study, greenhouse gases and ozone have contributed roughly equally in promoting a strong-wind, positive SAM phase in the troposphere, the lowest part of the atmosphere. Shindell and Schmidt used the NASA GISS Climate Model to run three sets of tests, each three times. For each scenario, the three runs were averaged together. Scenarios included the individual effects of greenhouse gases and ozone on the SAM, and then a third run that examined the effects of the two together. The model included interactions between the oceans and atmosphere. Each model run began in 1945 and extended through 2055. For the most part, the simulations matched well compared with past observations. Model inputs of increasing greenhouse gases were based upon observations through 1999, and upon the Intergovernmental Panel on Climate Change mid-range estimates of future emissions. Stratospheric ozone changes were based on earlier NASA GISS model runs that were found to be in good agreement with past observations and similar to those found in other chemistry-climate models for the future. Shindell said the biggest long-term danger of global warming in this region would be ice sheets melting and sliding into the ocean. "If Antarctica really does warm up like this, then we have to think seriously about what level of warming might cause the ice sheets to break free and greatly increase global sea levels," he said. In the Antarctic Peninsula, ice sheets as big as Rhode Island have already collapsed into the ocean due to warming. The warming in this area is at least partially a result of the strengthened westerly winds that pass at latitudes of about 60 to 65 degrees south. As the peninsula sticks out from the continent, these winds carry warm maritime air that heats the peninsula.

Ozone Holes

October 5, 2004

https://www.sciencedaily.com/releases/2004/10/041005072613.htm

Protecting Our Planet's Ozone Layer

Monitoring our planet's atmosphere has become an international priority. As successive world summits have stressed, our future on Earth could depend on safeguarding our environment.

The Royal Netherlands Meteorological Institute (KNMI) is using instruments on several satellites to follow the evolution of ozone around the planet. The gas comes in two flavours. On the one hand, at an altitude of 20-30 kilometres, natural ozone provides a protective layer, absorbing the Sun's harmful ultra-violet radiation. This 'good' ozone protects us from sunburn, skin cancer and eye problems.On the other hand, under the influence of sunlight, nitrogen oxides and hydrocarbons create toxic ozone on Earth's surface. This 'bad' ozone, part of air pollution or smog, may pose a particular health threat to those who already suffer from respiratory problems such as asthma, emphysema and chronic bronchitis. ESA's Earth observation satellite Envisat is one of the satellites sending back data to scientists at KNMI in Utrecht. One of its instruments called Sciamachy (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) monitors ozone and other trace gases on a regular and global basis. "The data from this instrument allows us to calculate the amounts of ozone from day to day," explains Dr Henke Eskes, atmospheric scientist at KNMI. "The coverage maps we obtain show the great variability of the ozone layer and we can precisely track the evolution of the ozone hole above the South Pole."Another European satellite ERS-2 carries a similar instrument called GOME. The United States also has a long experience in ozone monitoring with the TOMS (Total Ozone Mapping Spectrometer) instruments, and with its NOAA Earth observation satellites. Since last summer NASA has its AURA mission, dedicated to the study of the Earth's ozone, air quality and climate. The KNMI has the scientific lead of the Dutch-Finnish Ozone Monitoring Instrument (OMI) on AURA."OMI works by looking down at the Earth and measuring how much sunlight is reflected by the planet," says Pieternel Levelt, OMI's Principal investigator. "This provides indications of how much is being absorbed by atmospheric ozone."The 'good' ozone is under attack from man-produced species containing chlorine and bromine. Amongst these are the famous CFCs, Chlorofluorocarbons, which were used for instance in refrigerators, spray cans and foams. These CFCs greatly contributed to eating away the natural ozone.Efforts to safeguard our environment and the ozone layer appear to be fruitful. Banning of CFCs by the 1987 UN protocol seems to have stabilised the ozone hole. But the road ahead is still long: KNMI experts expect that pre-1980 average conditions of the 'good' ozone will only be recovered around 2050. The 'bad' ozone is a point of concern: studies predict that the rapid development of mega-cities and related increases in traffic will worsen the situation, increasing surface ozone.

Ozone Holes

September 2, 2004

https://www.sciencedaily.com/releases/2004/09/040902090247.htm

Envisat Witnesses Return Of The South Polar Ozone Hole

The smudges of dark blue on this Envisat-derived ozone forecast trace the start of what has unfortunately become an annual event: the opening of the ozone hole above the South Pole.

"Ever since this phenomenon was first discovered in the mid-1980s, satellites have served as an important means of monitoring it," explained José Achache, ESA Director of Earth Observation Programmes. "ESA satellites have been routinely observing stratospheric ozone concentrations for the last decade. "And because Envisat's observations are assimilated into atmospheric models, they actually serve as the basis of an operational ozone forecasting service. These models predict the ozone hole is in the process of opening this week." Envisat data show 2004's ozone hole is appearing about two weeks later than last year's, but at a similar time period to the average during the last decade. The precise time and range of Antarctic ozone hole occurrences are determined by regional meteorological variations. The ozone hole typically persists until November or December, when increasing regional temperatures cause the winds surrounding the South Pole to weaken, and ozone-poor air inside the vortex is mixed with ozone-rich air outside it. The ozone hole of 2002 was an exception to this general pattern, when a late September slowdown of the polar vortex caused the ozone hole to split in two and dissipate early. Envisat's predecessor mission, ERS-2, monitored the process. "Envisat carries an instrument called the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), based on a previous instrument flown aboard ERS-2, called the Global Ozone Monitoring Experiment (GOME)," said Henk Eskes of the Royal Netherlands Meteorological Institute (KNMI). "The two instruments give us a combined data set that stretches over ten years, one that Envisat adds to every day with fresh observations. "This data set presents a very good means of eventually identifying long-term trends in ozone. Whether or not the ozone layer is starting to recover is a hotly debated topic at the moment." The stratospheric ozone layer protects life on Earth from harmful ultraviolet (UV) radiation. The ozone thinning represented here is ultimately caused by the presence of man-made pollutants in the atmosphere such as chlorine, originating from man-made pollutants like chlorofluorocarbons (CFCs). Now banned under the Montreal Protocol, CFCs were once widely used in aerosol cans and refrigerators. CFCs themselves are inert, but ultraviolet radiation high in the atmosphere breaks them down into their constituent parts, which can be highly reactive with ozone. Just because they were banned does not mean these long-lived chemicals have vanished from the air, so scientists expect the annual South Polar ozone hole to continue to appear for many years to come. During the southern hemisphere winter, the atmospheric mass above the Antarctic continent is kept cut off from exchanges with mid-latitude air by prevailing winds known as the polar vortex. This leads to very low temperatures, and in the cold and continuous darkness of this season, polar stratospheric clouds are formed that contain chlorine. As the polar spring arrives, the combination of returning sunlight and the presence of polar stratospheric clouds leads to splitting of chlorine into highly ozone-reactive radicals that break ozone down into individual oxygen molecules. A single molecule of chlorine has the potential to break down thousands of molecules of ozone. ESA's ten-instrument Envisat spacecraft carries three instruments to measure the atmosphere; the results here come from SCIAMACHY, which provides global coverage of the distribution of ozone and other trace gases, as well as aerosols and clouds. KNMI processes SCIAMACHY data in near-real time as the basis of an operational ozone forecasting service. This is part of a suite of atmospheric information services provided by a project called TEMIS (Tropospheric Emission Monitoring Internet Service) that also includes UV radiation monitoring and forecasting. TEMIS is backed by ESA as part of the Agency's Data User Programme, intended to establish viable Earth Observation-based services for communities of users. The TEMIS atmospheric ozone forecast seen here has atmospheric ozone measured in Dobson Units (DUs), which stands for the total thickness of ozone in a given vertical column if it were concentrated into a single slab at standard temperature and atmospheric pressure – 400 DUs is equivalent to a thickness of four millimetres, for example. Launched in March 2002, ESA's Envisat satellite is an extremely powerful means of monitoring the state of our world and the impact of human activities upon it. Envisat carries ten sophisticated optical and radar instruments to observe and monitor the Earth's atmosphere, land, oceans and ice caps, maintaining continuity with the Agency's ERS missions started in 1991. After two and a half years in orbit, more than 700 scientists from 50 countries are about to meet at a special symposium in Salzburg in Austria to review and discuss early results from the satellites, and present their own research activities based on Envisat data. Starting next Monday, the Envisat Symposium will address almost all fields of Earth science, including atmospheric chemistry, coastal studies, radar and interferometry, winds and waves, vegetation and agriculture, landslides, natural risks, air pollution, ocean colour, oil spills and ice. There are over 650 being presented at the Symposium, selected by peer review. Presentations will include results on the Prestige oil spill, last year's forest fires in Portugal, the Elbe flooding in 2002, the evolution of the Antarctic ozone hole, the Bam earthquake and pollution in Europe. Numerous demonstrations are planned during the week in the ESA Exhibit area. An industrial consortium exhibit on the joint ESA-European Commission Global Monitoring for Environment and Security (GMES) initiative is also planned.

Ozone Holes

July 15, 2004

https://www.sciencedaily.com/releases/2004/07/040715093844.htm

Aura Spacecraft Launched To Better Understand The Air We Breathe

Aura, a mission dedicated to the health of Earth's atmosphere, successfully launched today at 3:01:59 a.m. Pacific Time from the Western Range of Vandenberg Air Force Base, Calif., aboard a Boeing Delta II rocket. Spacecraft separation occurred at 4:06 a.m. Pacific Time, inserting Aura into a 705-kilometer (438-mile) orbit.

NASA's latest Earth-observing satellite, Aura will help us understand and protect the air we breathe. "This moment marks a tremendous achievement for the NASA family and our international partners," said NASA Associate Administrator for Earth Science Dr. Ghassem Asrar. "We look forward to the Aura satellite offering us historic insight into the tough issues of global air quality, ozone recovery and climate change. "This mission advances NASA's exploration of Earth and will also better our understanding of our neighbors in the planetary system," he added. "Aura joins its siblings, Terra, Aqua and 10 more research satellites developed and launched by NASA during the past decade, to study our home planet, Earth." "Many people have worked very hard to reach this point and the entire team is very excited," said Aura Project Manager Rick Pickering of NASA's Goddard Space Flight Center, Greenbelt, Md. With the launch of Aura, the first series of NASA's Earth Observing System satellites is complete. The other satellites are Terra, which monitors land, and Aqua, which observes Earth's water cycle. Aura will help answer three key scientific questions: Is the Earth's protective ozone layer recovering? What are the processes controlling air quality? How is the Earth's climate changing? NASA expects early scientific data from Aura within 30-90 days. Aura will also help scientists understand how the composition of the atmosphere affects and responds to Earth's changing climate. The results from this mission will help scientists better understand the processes that connect local and global air quality. Each of Aura's four instruments is designed to survey different aspects of Earth's atmosphere. Aura will survey the atmosphere from the troposphere, where mankind lives, through the stratosphere, where the ozone layer resides and protects life on Earth. Aura's four instruments are: the High Resolution Dynamics Limb Sounder (HIRDLS); the Microwave Limb Sounder (MLS); the Ozone Monitoring Instrument (OMI); and the Tropospheric Emission Spectrometer (TES). NASA's Jet Propulsion Laboratory, Pasadena, Calif., developed and manages MLS and TES. HIRDLS was built by the United Kingdom and the United States. OMI was built by the Netherlands and Finland in collaboration with NASA. NASA's Goddard Space Flight Center manages the Aura mission. The Microwave Limb Sounder is intended to improve our understanding of ozone in Earth's stratosphere, which is vital in protecting us from solar ultraviolet radiation. The Tropospheric Emission Spectrometer is an infrared sensor designed to study Earth's troposphere and to look at ozone and other urban pollutants. NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space. For Aura information and images on the Internet, visit: For more information about MLS on the Internet, visit: For more information about TES on the Internet, visit: The California Institute of Technology in Pasadena manages JPL for NASA.

Ozone Holes

July 8, 2004

https://www.sciencedaily.com/releases/2004/07/040708004132.htm

New Space-Borne Instrument To Track Greenhouse Gases, Ozone Destroyers, And Other Pollutants

BOULDER -- A powerful new instrument heading to space this Saturday is expected to send back long-sought answers about greenhouse gases, atmospheric cleansers and pollutants, and the destruction and recovery of the ozone layer. Only a cubic yard in size but laden with technical wizardry, the High-Resolution Dynamic Limb Sounder (HIRDLS) will measure a slew of atmospheric chemicals at a horizontal and vertical precision unprecedented in a multi-year space instrument.

Scientists at the National Center for Atmospheric Research (NCAR), University of Colorado, and University of Oxford developed HIRDLS (pronounced "hurdles") with funding from NASA and United Kingdom sources. The U.S. space agency plans to launch the 21-channel radiometer along with three other instruments July 10 aboard its Aura satellite from Vandenberg Air Force Base in California.HIRDLS will capture the chemistry and dynamics of four layers of the atmosphere that together span a region 8 to 80 kilometers (5 to 50 miles) above Earth’s surface: the upper troposphere, the tropopause, the stratosphere, and the mesosphere.Using infrared radiation as its yardstick, the radiometer will look through Earth’s atmosphere toward the planet’s limb, or edge. It will find and measure ten different chemical species, characterize airborne particles known as aerosols, and track thin cirrus clouds, all at a vertical resolution of half a kilometer (a third of a mile) and a horizontal resolution of 50 kilometers (30 miles). The signal-to noise ratio is one tenth that of previous detectors."The angular resolution of the instrument’s mirror position is equivalent to seeing a dime eight miles away," says principal investigator John Gille, of NCAR and the University of Colorado.A few questions HIRDLS data will answerWhat are the concentrations of the primary greenhouse gases and their height in the atmosphere?—The answer should reveal where Earth will warm or cool as the global climate changes.Why does the tropopause exist and what is its role in conveying gases from the troposphere into the stratosphere, especially in the tropics?—Convection was once thought to be the vehicle, but scientists now know warm, rising air normally stops at the frigid, dry tropopause.Why is the stratosphere, historically dry, now getting wetter?—The answer could shed light on how a changing climate is modifying the atmosphere and how those modifications could in turn feed back into our climate and weather near the ground.How much ozone is sinking from the stratosphere into the upper troposphere?—The answer will help scientists separate natural ozone pollution from human-made sources and give new information on how the gas is affecting chemistry closer to the ground.Scientists also expect to see clearly for the first time the dynamic processes that cause water vapor filaments and tendrils to break off and mix with other gases in the troposphere.Good and bad ozone at different altitudesAt 50 kilometers (30 miles) above the ground, ozone is good: it blocks dangerous ultraviolet radiation and prevents it from harming life and materials at ground level. At 10 kilometers (6 miles), ozone is a greenhouse gas, which is good because the natural greenhouse effect is necessary to warm the planet, but bad if the warming continues to increase at too rapid a rate. At 5 kilometers (3 miles), ozone is a source of the hydroxyl radical, which cleanses the atmosphere of pollutants. But at ground level, ozone is a primary pollutant in smog, causing respiratory problems and damaging trees and crops.NCAR's primary sponsor, the National Science Foundation, provided additional support for the research that made HIRDLS possible.

Ozone Holes

June 1, 2004

https://www.sciencedaily.com/releases/2004/05/040531212755.htm

Gene At Root Of Urban Air Pollution's Lung Effects

ORLANDO, Fla. – Duke University Medical Center pulmonologists have linked a gene to the lung irritation commonly suffered following chronic exposure to ozone, a major component of urban air pollution. Should the new finding in mice be corroborated in human studies, drugs that block the function of the gene might serve as useful treatments for patients with asthma, the researchers said.

The new study adds to earlier work highlighting the importance of genetic factors in determining the lung's response to environmental toxins by pinpointing a key player in the process, said Duke pulmonologist John Hollingsworth II, M.D., lead author of the study. "The lung is constantly exposed to a broad spectrum of environmental toxins, which can impact the severity of asthma," said Hollingsworth. "While the body's response to environmental exposures can facilitate the clearance of pathogens, it can also lead to injury and compromised lung function. By understanding the molecular mechanisms that initiate inflammation and injury, we may advance on new treatments to prevent the damage." Hollingsworth presented the research at the 100th International Conference of the American Thoracic Society on May 25, 2004. The study will also appear in a forthcoming issue of the American Journal of Respiratory and Critical Care Medicine. The work was supported by the Department of Veterans' Affairs, the National Institute of Environmental Health Sciences, the National Heart Lung and Blood Institute and GlaxoSmithKline. Ozone is an unstable molecule comprising three oxygen atoms. Natural ozone in the upper atmosphere plays an important role in filtering out ultraviolet rays from the sun. In the lower atmosphere, however, man-made ozone pollution results from a chemical reaction with nitrous oxide compounds released in automobile exhaust and industrial emissions, particularly under warm, sunny conditions. Such ozone is toxic in small concentrations and can exacerbate asthma and other respiratory conditions. The researchers exposed mice with and without a functional copy of the gene TLR4 to four environmental challenges. They were aerosolized lipopolysaccharide, a component of bacterial cell membranes ubiquitous in the environment, particulate matter, and high and low doses of ozone. TLR4 encodes a component of the innate immune system, the body's first line of defense against foreign invaders. Earlier work linked the gene to the lung's response to bacterial infection and inhaled lipopolysaccharides, Hollingsworth said, a result which the current study confirmed. Research led by Steve Kleeberger, Ph.D., of the National Institute of Environmental Health Sciences, had further suggested a role for the gene in airway injury induced by ozone, he added. The new study expands TLR4's role in directing the lung's response to environmental exposures by highlighting its potential importance in exacerbation of asthma following ozone inhalation. The researchers found that ozone levels comparable to those experienced during consecutive red alert days -- during which the U.S. Environmental Protection Agency recommends people limit outdoor activity -- also led to the hyper-responsiveness or twitching of the lungs characteristic of asthma only in animals with a working copy of the innate immunity gene. Mice lacking a functional copy of TLR4 continued to suffer lung injury in response to particulate matter and acute ozone exposure. However, they were protected from many of the airway effects of prolonged exposure to lower doses of ozone. The result suggests that the ramifications of toxin inhalation in the lung vary depending upon the nature of the toxin and exposure conditions, Hollingsworth said. "Ozone exposure is important in the big picture, particularly in urban settings," he said. "Drugs that target the components critical to the lung's response to such exposures might serve as effective treatments for patients with asthma." The Duke team will next conduct studies of humans to confirm the gene's importance to the effects of inhaled air pollution. The human and mouse genes are known to play similar functional roles in innate immunity. Collaborators on the study include Donald Cook, Ph.D., David Brass, Ph.D., Julia Walker, Ph.D., W. Michael Foster, Ph.D., and David A. Schwartz, M.D., all of Duke. Daniel Morgan, Ph.D., of the National Institute of Environmental Health Sciences also contributed to the research.

Ozone Holes

May 18, 2004

https://www.sciencedaily.com/releases/2004/05/040518073610.htm

NASA Plans To Put An Aura Around The Earth

On June 19, NASA will launch Aura, a next generation Earth-observing satellite. Aura will supply the best information yet about the health of Earth's atmosphere.

Aura will help scientists understand how atmospheric composition affects and responds to Earth's changing climate. The satellite will help reveal the processes that connect local and global air quality. It will also track the extent Earth's protective ozone layer is recovering.Aura will carry four instruments each designed to survey different aspects of Earth's atmosphere. The instruments will provide an unprecedented and complete picture of the composition of the atmosphere. Aura will survey the atmosphere from the troposphere, where mankind lives, through the stratosphere, where the ozone layer resides and protects life on Earth.Aura's space-based view of the atmosphere and its chemistry will complete the first series of NASA's Earth Observing System satellites. The other satellites are, Terra, which monitors land, and Aqua, which observes Earth's water cycle."Gaining this global view of Earth will certainly reap new scientific discoveries that will serve as essential stepping stones to our further exploration of the Moon, Mars and beyond, the basis of the Vision for Space Exploration," NASA Administrator Sean O'Keefe said.Aura will help answer key scientific questions, including whether the ozone layer is recovering. Aura data may prove useful determing the effectiveness of international agreements, which banned ozone-depleting chemicals like chlorofluorocarbons. (CFCs)Aura will accurately detect global levels of CFCs, and their byproducts, chlorine and bromine, which destroy ozone. Aura will also track the sources and processes controlling global and regional air quality. It will help distinguish between natural and human-caused sources of these gases. When ozone exists in the troposphere, it acts as an air pollutant. Tropospheric ozone is linked to high levels of precursors such as nitrogen dioxide, carbon monoxide and volatile hydrocarbons. Aura will help scientists follow the sources of tropospheric ozone and its precursors."Aura, the first comprehensive laboratory in space to help us better understand the chemistry and composition of the Earth's atmosphere, is fundamentally a mission to understand and protect the very air we breathe, " said NASA Associate Administrator for Earth Science Dr. Ghassem Asrar. "It is also a perfect complement to our other Earth Observing System satellites that, together, will aid our nation and our neighbors by determining the extent, causes, and regional consequences of global change," he said.As the composition of Earth's atmosphere changes, so does its ability to absorb, reflect and retain solar energy. Greenhouse gases, including water vapor, trap heat in the atmosphere. Airborne aerosols from human and natural sources absorb or reflect solar energy based on color, shape, size, and substance. The impact of aerosols, tropospheric ozone and upper tropospheric water vapor on Earth's climate remains largely unquantified. Aura's ability to monitor these agents will help unravel some of their mystery.Aura's four instruments, the High Resolution Dynamics Limb Sounder (HIRDLS); the Microwave Limb Sounder (MLS); the Ozone Monitoring Instrument (OMI); and the Tropospheric Emission Spectrometer (TES) will work together to provide measurements in the troposphere and stratosphere to help answer important climate questions.HIRDLS was built by the United Kingdom and the United States. OMI was built by the Netherlands and Finland in collaboration with NASA. NASA's Jet Propulsion Laboratory, Pasadena, Calif., constructed TES and MLS. NASA's Goddard Space Flight Center, Greenbelt, Md., manages the Aura mission.NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.For Aura information and images on the Internet, visit: &

Ozone Holes

May 17, 2004

https://www.sciencedaily.com/releases/2004/05/040517072915.htm

Increasing Ozone Over The Atlantic Ocean

Ship-borne ozone measurements, performed by researchers of the Max Planck Institute for Chemistry and the German Weather Service over the Atlantic Ocean during the period 1977-2002, show that the ozone trends in the northern mid-latitudes are small. In contrast, remarkably large ozone trends occur at low latitudes and in the Southern Hemisphere, implying that the ozone smog problem has expanded far beyond the areas traditionally affected by photochemical air pollution in Europe and the USA (Science Express, 13 May, 2004).

Ozone smog was first discovered in the Los Angeles basin in the 1940s, an area where traffic emissions of nitrogen oxides (NO and NO2) efficiently promote photochemical air pollution. The nitrogen oxides, released from the combustion of fossil fuels and also by biomass burning, act as catalysts of ozone formation. In turn, this reduces air quality and impairs human health, agricultural crops and natural ecosystems. Furthermore, ozone is a greenhouse gas, so that its increasing concentration in the troposphere contributes to climate change. In the post-war industrialization in the 1960s and 1970s, ozone increased rapidly in Europe and the USA. In addition to Los Angeles, especially the eastern USA and southern Europe suffer from high ozone concentrations in summer, so that air quality standards are often violated. Nevertheless, the ozone increases have been moderated after 1980 by the introduction of catalytic converters in car exhausts and the mitigation of industrial air pollution. The article in Science is based on ozone measurements by the Max Planck Institute for Chemistry (Mainz) and the German Weather Service (Hohenpeißenberg and former Meteorological Observatory Hamburg), taken on ships sailing the Atlantic Ocean since 1977. The results confirm that in middle latitudes in the northern hemisphere the ozone concentrations are quite high, although the increases since about 1980 have not been very large. Remarkably and unexpectedly, however, in the subtropics, the tropics and the southern hemisphere, ozone increases since 1980 have been much larger. In some regions the ozone levels have even doubled in two decades. The area where the high ozone concentrations have been measured is mostly downwind of Africa, and the researchers have calculated that biomass burning and especially increasing energy use on this continent have contributed substantially to emissions of nitrogen oxides, thus catalyzing ozone formation. The implication is that increasing energy use worldwide causes large-scale ozone increases, thus reducing global air quality. ###Original work: Jos Lelieveld, John van Aardenne, Horst Fischer, Marian de Reus, Jonathan Williams and Peter Winkler Increasing ozone over the Atlantic OceanScience Express, 13 May 2004

Ozone Holes

May 6, 2004

https://www.sciencedaily.com/releases/2004/05/040506073316.htm

Missing Chemical Important To Air Pollution Estimates

University Park, Pa. -- Something is missing in the analysis of emissions of volatile organic compounds from a Michigan forest, and, according to a team of atmospheric scientists, what they do not know can have a large impact on air pollution in areas in and near forests.

"Organic compounds emitted by some trees play a role in ozone and aerosol production in the lower atmosphere," says William H. Brune, professor of meteorology and head of Penn State's department of meteorology. "It appears that, at least in wooded areas, we have been underestimating the amounts of these chemicals produced." The researchers were looking at the production of hydroxyl radical in the atmosphere. Volatile organic compounds like isoprene react with the hydroxyl radical resulting in the production of ozone and other chemicals. There has been some discrepancy between the actual measurement of hydroxyl radicals in the atmosphere and what the models predict. "We developed a device that can measure the reactivity of hydroxyl radical in the air," says Brune. "Then we decided to measure everything in the atmosphere that reacts with the hydroxyl radical." The researchers reported the results of this experiment in the April 30 issue of Science. The researchers, who included Brune; Piero Di Carlo, a postdoctoral fellow from the Universita di L'Aquila in Italy who worked with Brune; Monica Martinez and Hartwig Harder, former post doctoral fellows, Robert Lesher, research assistant in electrical engineering, and Xinrong Ren, postdoctoral fellow, all at Penn State, measured the hydroxyl radical and the other chemicals in a forest in Northern Michigan at the University of Michigan Biological Station. The researchers took measurements from a tower above the canopy of a mixed transition forest of northern hardwood, aspen and white pine. Over a two-year period, the researchers also collected a wide array of data on the area, including temperatures, chemical constituents and where the air masses came from. "When we measured an air mass coming from Detroit, we found all the urban pollutants one would expect, but we also found that the levels of chemicals were not dependent upon local temperature profiles," says Brune. "The urban readings were flat with respect to temperature change." But the researchers found that chemicals in air masses that came from the forested area did change with a change in temperature. Forest-generated emissions change a lot with temperature. Isoprene is the forest-generated chemical with the largest piece of the emission pie, but it is only produced during daylight. Other chemicals, particularly larger terpenes, are produced around the clock and are also temperature sensitive. "We think we measured all major components of the hydroxyl radical reactants, but there is something still unaccounted for,” says Brune. "We know that something we cannot identify is reacting with the hydroxyl radicals and we know it is temperature dependent and not light dependent. We just do not know what it is." This missing substance is not trivial. It makes up a fourth to a third of the reactants, with the hydroxyl radical in the forest, which is significant. Because it is temperature sensitive, and is seen in both clean and polluted air at the forest site, it is forest-generated, not city-generated. "We followed up the Michigan experiment with one in Houston," says Brune. "There we saw all the expected compounds from cars, oil refining, asphalt and burger joints, but the hydroxyl reactivity was not temperature dependent. We could account for all the hydroxyl reactivity." In New York City and Nashville as well as Houston, no temperature dependency was found. Because hydroxyl radicals play an important part in the production of tropospheric ozone and are key in many of the chemical reactions that break down pollutants in the atmosphere, understanding exactly how much hydroxyl radical is actually in the atmosphere is important for measuring and predicting pollution levels. If researchers are consistently underestimating the volatile organic compounds generated by forests, their analysis of the environment, especially in cities surrounded by forests, will be incorrect. Applying environmental regulations and assessing pollution levels becomes very difficult with incomplete information. The researchers note that, "New, more specific and more sensitive detection techniques will likely be required to determine the identity of the biologically produced volatile organic compounds responsible for the missing hydroxyl radical reactivity and the reason they have not yet been detected." This work was part of the PROPHET 1998 and PROPHET 2000 campaigns and was funded by the National Science Foundation, the National Oceanographic and Atmospheric Agency and the U.S. Environmental Protection Agency. Other researchers involved in the project were Troy Thornberry, Coleen Campbell and Mary Anne Carroll, University of Michigan; Valerie Young, Ohio University; Paul B. Shepson, Purdue University; Daniel Riemer, University of Miami, and Eric Apel, NCAR.

Ozone Holes

May 4, 2004

https://www.sciencedaily.com/releases/2004/05/040504062245.htm

NASA Satellites And Balloons Spot Airborne Pollution 'Train'

NASA scientists discovered pollution could catch an airborne "express train," or wind current, from Asia all the way to the southern Atlantic Ocean.

Scientists believe during certain seasons, as much as half of the ozone pollution above the Atlantic Ocean may be speeding down a "train" track of air from the Indian Ocean. As it rolls along, it picks up more smog from air peppered with thunderstorms that bring it up from the Earth's surface. Bob Chatfield, a scientist at NASA's Ames Research Center, Moffett Field, Calif. said, "Man-made pollution from Asia can flow southward, get caught up into clouds, and then move steadily and rapidly westward across Africa and the Atlantic, reaching as far as Brazil." Chatfield and Anne Thompson, a scientist at NASA's Goddard Spaceflight Center, Greenbelt, Md., used data from two satellites and a series of balloon-borne sensors to spot situations when near-surface smog could "catch the train" westward several times annually from January to April. During those periods of exceptionally high ozone in the South Atlantic, especially during late winter, researchers noticed Indian Ocean pollution follows a similar westward route, wafted by winds in the upper air. They found the pollution eventually piles up in the South Atlantic. "We've always had some difficulty explaining all that ozone," Thompson admitted. Seasonal episodes of unusually high ozone levels over the South Atlantic seem to begin with pollution sources thousands of miles away in southern Asia," Chatfield said. Winds are known to transport ozone and pollutants thousands of miles away from their original sources. Clearly defined individual layers of ozone in the tropical South Atlantic were traced to lightning sources over nearby continents. In addition to ozone peaks associated with lightning, high levels of ozone pollution came from those spots in the Sahel area of North Africa where vegetation burned. However, even outside these areas, there was extra ozone pollution brought by the Asian "express train." The scientists pinpointed these using the joint NASA-Japan Tropical Rainfall Measuring Mission satellite to see fires and lightning strikes, both of which promote ozone in the lower atmosphere. Researchers also identified large areas of ozone smog moving high over Africa using the Total Ozone Mapping Spectrometer satellite instrument. The scientists confirmed the movement of the smog by using sensors on balloons in the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. A computer model helped track the ozone train seen along the way by the SHADOZ balloon and satellite sensors. The scientists recreated the movement of the ozone from the Indian Ocean region to the Southern Atlantic Ocean. Their research results appear in an article in a recent issue of the American Geophysical Union's Geophysical Research Letters. The mission of NASA's Earth Science Enterprise is to develop a scientific understanding of the Earth system and its response to natural or human-induced changes to enable improved prediction capability for climate, weather, and natural hazards.

Ozone Holes

April 26, 2004

https://www.sciencedaily.com/releases/2004/04/040426053953.htm

Arctic Ozone Loss More Sensitive To Climate Change Than Thought

A cooperative study involving NASA scientists quantifies, for the first time, the relationship between Arctic ozone loss and changes in the temperature of Earth's stratosphere.

The results indicate the loss of Arctic ozone due to the presence of industrial chlorine and bromine in Earth's atmosphere may well be sensitive to subtle changes in stratospheric climate. Such ozone depletion leads to increased exposure to harmful, ultraviolet solar radiation at Earth's surface. According to the study, the sensitivity of Arctic ozone to temperature is three times greater than predicted by atmospheric chemistry models. This leads to the possibility that decreases in stratospheric temperatures may have significantly larger impacts on future Arctic ozone concentrations than have been expected in the past. Dr. Markus Rex of the Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany, led the study. It also included scientists from NASA's Jet Propulsion Laboratory, Pasadena, Calif. The researchers analyzed more than 2,000 balloon measurements collected over the past 12 years. They found the amount of ozone loss occurring in any given Arctic winter is closely related to the amount of air exposed to temperatures low enough to support the formation of polar stratospheric clouds. Reactions occurring on the surface of these clouds convert chlorine from unreactive forms to other forms that quickly deplete ozone. Based on the relation between ozone loss and polar stratospheric cloud existence, the researchers found every degree Kelvin (equal to one Celsius degree) cooling of the Arctic results in an additional ozone destruction of five percent. This sensitivity is a factor of three larger than previously predicted by state-of-the-art, coupled climate- chemistry computer models. The scientists found the coldest stratospheric winters, during which most of the ozone loss occurs due to greater polar stratospheric cloud formation, have gradually become significantly cooler during the past few decades. "If stratospheric climatic conditions had not changed since the 1960s, Arctic ozone loss would be much less severe today, despite the increase in chlorofluorocarbons and bromine," Rex said. "This study presents a new method of looking at a multi-year data set that enables us to relate year-to-year variations in the amount of ozone depletion to climate change," said co- author Dr. Ross Salawitch, a JPL research scientist. "Results of this research will lead to substantially improved computer model simulations of this phenomenon and will provide an excellent method for analyzing data from satellites such as NASA's soon-to-be-launched Aura atmospheric chemistry laboratory." Researchers are trying to understand why the Arctic stratosphere cools. It may be due to a number of factors: rising levels of greenhouse gases such as carbon dioxide; a feedback between ozone depletion and stratospheric temperature; and natural variability. Higher amounts of greenhouse gases trap heat near Earth's surface, warming the surface and preventing the heat from reaching the stratosphere, thus cooling the upper atmosphere. However, climate models vary widely in their estimates of how much stratospheric cooling has occurred due to rising greenhouse gases over the past 40 years. Stratospheric chlorine and bromine have begun to decline in response to the Montreal Protocol, a worldwide agreement signed in 1987 that limits the production of chlorofluorocarbons and other ozone depleting pollutants. Scientists believe this indicates the cleansing process has begun, and eventually the ozone layer will recover, although chlorofluorocarbons can stay in the atmosphere for 50 to 100 years. The study suggests the healing process might be slowed, in the short term, by changes in stratospheric climate. Tracking the predicted recovery of the ozone layer is a key science objective of NASA's Aura spacecraft. Aura is the latest in the Earth Observing System series and scheduled for launch in June. Aura will study the atmosphere's chemistry and dynamics, providing data to help scientists better understand Earth's ozone, air quality and climate change. Aura's chemistry measurements will follow up on records that began with NASA's Upper Atmospheric Research Satellite and will also continue the Total Ozone Mapping Spectrometer mission's goal of collecting comprehensive ozone data. The paper was highlighted by the American Geophysical Union and published in Geophysical Research Letters, Volume 31, L04116. For information about the research on the Internet, visit: JPL is managed for NASA by the California Institute of Technology, Pasadena, Calif.

Ozone Holes

April 21, 2004

https://www.sciencedaily.com/releases/2004/04/040416014848.htm

Like Ozone Hole, Polar Clouds Take Bite Out Of Meteoric Iron

CHAMPAIGN, Ill. -- Polar clouds are known to play a major role in the destruction of Earth's protective ozone layer, creating the springtime "ozone hole" above Antarctica. Now, scientists have found that polar clouds also play a significant role in removing meteoric iron from Earth's mesosphere. The discovery could help researchers refine their models of atmospheric chemistry and global warming.

Using a sensitive laser radar (lidar) system, laboratory experiments and computer modeling, researchers from the University of Illinois at Urbana-Champaign and the University of East Anglia in Norwich, England, studied the removal of meteoric iron by polar mesospheric clouds that they observed during the summer at the South Pole."Our measurements and models have shown that another type of reaction that takes place in the upper atmosphere -- this time related to ice particles -- plays a very important role in the processes that influence the chemistry of metal layers in this region," said Chester Gardner, a professor of electrical and computer engineering at Illinois and one of the co-authors of a paper to appear in the April 16 issue of the journal Science.First deployed over Okinawa, Japan, to observe meteor trails during the 1998 Leonid meteor shower, the Illinois lidar system uses two powerful lasers operating in the near ultraviolet region of the spectrum and two telescopes to detect laser pulses reflected from the atmosphere. The system was moved to the Amundsen-Scott South Pole Station in late 1999."Simultaneous observations of the iron layer and the clouds revealed nearly complete removal of iron atoms inside the clouds," Gardner said. "Laboratory experiments and atmospheric modeling done by our colleagues at the University of East Anglia then showed that this phenomenon could be explained by the efficient uptake of iron on the surfaces of ice crystals."Polar mesospheric clouds are the highest on Earth, forming at an altitude of about 52 miles. The clouds form over the summertime polar caps when temperatures fall below minus 125 degrees Celsius, and overlap a layer of iron atoms produced by the ablation of meteoroids entering the atmosphere."At such cold temperatures, the iron atoms stick when they bump into the ice crystals," Gardner said. "If the removal of iron is rapid compared to both the input of fresh meteoric ablation and the vertical transport of iron into the clouds, a local depletion or 'bite-out' in the iron layer will result." To examine whether the observed bite-outs could be fully explained by the removal of iron atoms by ice particles, John Plane, a professor of environmental sciences at East Anglia, and graduate student Benjamin Murray measured the rate of iron uptake on ice.In their laboratory, Plane and Murray first deposited a layer of ice on the inside of a flow tube. Iron atoms were then generated by laser ablation of an iron target at one end of the tube. At the other end, a second laser measured how much iron made it through the tube."By changing the temperature in the tube, we could compare how much iron was absorbed by the ice and calculate the sticking coefficient," Plane said. "Once we knew how efficiently the iron atoms stick to the ice, our next question was whether there was enough ice surface in the polar clouds to deplete the iron and cause the dramatic bite-outs revealed in the lidar observations."The researchers answered this question by carefully modeling the size distribution of ice particles as a function of altitude. They concluded there was sufficient surface area to remove the iron."Our results clearly demonstrate the importance of ice particles in the chemistry of this region of the atmosphere," Gardner said. "Not too many years ago we learned how important polar stratospheric clouds were to the chemistry of the ozone layer. Now we are seeing something very similar happening at higher altitudes."In addition to Gardner, Plane and Murray, the team included research scientist Xinzhao Chu from the University of Illinois who made the measurements at the South Pole.The National Science Foundation, the Royal Society and the Natural Environmental Research Council funded the work.

Ozone Holes

April 13, 2004

https://www.sciencedaily.com/releases/2004/04/040413002358.htm

Nighttime Chemistry Affects Ozone Formation

WASHINGTON - When it comes to air pollution, what goes on at night can be just as important as what happens during the day, say National Oceanic and Atmospheric Administration (NOAA) scientists and their colleagues in a study published 10 April in Geophysical Research Letters.

The scientists found that nighttime chemical processes remove nitrogen oxides (NOx) from the atmosphere in the marine boundary layer off the coast of New England. These gases are one of the two basic ingredients for making ozone pollution. With less nitrogen oxides in the atmosphere, ozone production the next day will almost always be reduced in New England. Ozone is a strong oxidant and can lead to respiratory problems in humans, as well as affect plant life. Lead author Steven S. Brown and many of his co-authors are at NOAA's Aeronomy Laboratory and NOAA's Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado. Scientists at the NOAA Pacific Marine Environmental Laboratory, the University of New Hampshire, and the University of Colorado also participated in the study.Ozone forms in the presence of sunlight from chemical reactions between hydrocarbons (also known as volatile organic compounds, or VOCs) and nitrogen oxides, both of which are emitted by human activities such as fossil-fuel burning, as well as by natural sources. Most studies have focused on the daytime processes associated with ozone pollution.But, Brown notes, "Atmospheric chemistry never sleeps" and more information is needed about nighttime chemistry. After sunset, nitrogen oxide compounds undergo reactions that make two new nitrogen-containing gases that exist mainly at night. These "nocturnal nitrogen oxides" have the potential to either remove nitrogen from the atmosphere or to store it and re-release it when daylight returns--two possibilities that have vastly different consequences for subsequent ozone formation.The authors studied the two nocturnal gases, known chemically as nitrate radical (NO3) and dinitrogen pentoxide (N2O5). The gases had been previously either impossible to measure (dinitrogen pentoxide) or measurable only over a large volume of air (nitrate radical). A new capability recently applied by Brown and his colleagues has made it possible to measure each gas in a small volume of sampled air. The scientists got their first look at the nighttime chemistry during the summer of 2002, when the new instrument was deployed off the coast of New England on the NOAA Research Vessel Ronald H. Brown, as part of an air quality study of the region.They found that the nocturnal gases effectively removed nitrogen oxides from the atmosphere by forming nitric acid, a gas that rapidly deposits to the surface in the marine environment that the scientists investigated. The net result is that the nitrogen oxides that are thus removed can no longer participate in ozone-forming chemistry the next day. Scientists at the University of New Hampshire provided key measurements of the nitric acid during the study."This nighttime process takes out about as much as daytime processes. Under nearly all polluted conditions, this will short-circuit some of the ozone production that would have occurred the next day in New England," Brown says.The result is important to include in air quality models of the region, because it affects the amount of ozone that is expected to form per unit of nitrogen oxide pollution. New nighttime processes are a "must-have" for air quality forecasts and simulations in New England, and perhaps other areas, the researchers say."The nighttime chemistry is a new piece of the air quality puzzle. We need to find out more about when and where it is important, so that we will be able to provide more accurate predictions of ozone pollution for the public," said A.R. Ravishankara, a co-author of the study at NOAA's Aeronomy Laboratory.The research was funded by the New England Air Quality Study and NOAA.

Ozone Holes

April 13, 2004

https://www.sciencedaily.com/releases/2004/04/040412014155.htm

NASA's Aura Satellite Delivered To Launch Site

NASA's Aura spacecraft, the latest in the Earth Observing System series, has arrived at Vandenberg Air Force Base, Calif., to begin launch preparations.

Aura was transported from Northrop Grumman's Space Park manufacturing facility in Redondo Beach, Calif. The spacecraft will undergo final tests and integration with a Boeing Delta II rocket for a scheduled launch in June. Aura's four state-of-the-art instruments, including two built and managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., will study the atmosphere's chemistry and dynamics. The spacecraft will provide data to help scientists better understand Earth's ozone, air quality and climate change. JPL's Tropospheric Emission Spectrometer is an infrared sensor designed to study Earth's troposphere-the lowest region of the atmosphere-and to look at ozone. JPL's Microwave Limb Sounder is an instrument intended to improve our understanding of ozone in Earth's stratosphere, vital in protecting us from solar ultraviolet radiation. "The entire Aura team is very excited to see all our efforts come to fruition and is looking forward to a successful launch," said Rick Pickering, Aura project manager at NASA's Goddard Space Flight Center in Greenbelt, Md. Aura fulfills part of NASA's commitment to study Earth as a global system and represents a key agency contribution to the U.S. Global Change Research Program. This mission will continue the global data collection underway by NASA's other Earth Observing System satellites: Terra, which monitors land; and Aqua, which observes Earth's water cycle. The Aura spacecraft is part of NASA's Earth Science Enterprise, a long-term research effort to determine how human-induced and natural changes affect the global environment. For more information about Aura on the Internet, visit JPL is managed for NASA by the California Institute of Technology in Pasadena.

Ozone Holes

April 9, 2004

https://www.sciencedaily.com/releases/2004/04/040409091917.htm

Livermore Scientists Contribute To New Measurements Of Stratospheric Ozone

LIVERMORE, Calif. -- A team of scientists, including two from the Lawrence Livermore National Laboratory, have identified a new method to measure the amount of stratospheric ozone that is present at any given time in the upper troposphere.

Working with researchers from the National Oceanic and Atmospheric Administration, the University of Colorado, the Jet Propulsion Laboratory, the National Center for Atmospheric Research, NASA Ames Research Center and Harvard University, atmospheric scientists Cyndi Atherton and Dan Bergmann successfully quantified ozone transport down from the stratosphere during NASA's 2002 CRYSTAL-FACE mission over Florida.The research is presented in the April 9 edition of the journal Science. The atmosphere has several levels: the lowest is the turbulently mixed troposphere, which extends from the Earth's surface up to approximately 10 kilometers, and the second level is the more stable stratosphere, which extends from 10 to 50 kilometers above the surface and contains 90 percent of the world's ozone. The tropopause is the transition zone between the two and is appoximately the altitude of commercial aircraft flight.A team of scientists within LLNL's Atmospheric Science Division created a computer model that can simulate how both ozone (O3) and hydrogen chloride (HCl) in the stratosphere travel downward across the tropopause and into the upper troposphere. Atherton and Bergmann used this model to simulate specific atmospheric events. These results, when compared to measurements, validated a novel technique that uses HCl measurements to better understand the contribution of the stratosphere to upper tropospheric ozone concentrations. Upper tropospheric ozone plays an important role in global warming and climate change. Ozone is a highly reactive and toxic gas. Although it blocks incoming harmful radiation, it also acts as a greenhouse gas, respiratory irritant, and can damage materials and crops. "This research shows that there are times when a significant amount of the ozone found in the upper troposphere was due to stratosphere-to-troposphere transport events," Atherton said. "Continued use of this measurement method will lead to a better understanding of how much of this material is transported to the upper troposphere, where it affects climate and the chemical balance of the atmosphere."Until now, no experimental technique could reliably quantify stratospheric ozone in the upper troposphere. Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

Ozone Holes

March 24, 2004

https://www.sciencedaily.com/releases/2004/03/040324071553.htm

Ozone-destroying Gas In Atmostphere Increased Significantly During Industrial Age, Study Shows

Irvine, Calif., March 23, 2004 -- Human activity in the Industrial Age -- approximately the last 150 years -- has significantly increased atmospheric levels of methyl bromide, a gas known for harming the ozone layer in the Earth's stratosphere.

A research team led by UC Irvine scientist Eric Saltzman reached this conclusion after examining an ice core recovered from Antarctica. By studying air bubbles trapped in the core, Saltzman's team was able to compare levels of methyl bromide in the atmosphere over the last three centuries. The team concluded that during the industrial era, the amount of global atmospheric methyl bromide in Southern Hemisphere air appears to have increased by 3.5 parts per trillion, or approximately 50 percent of the preindustrial level of the gas. The researchers report their findings in the March 2, 2004, issue of the Journal of Geophysical Research – Atmospheres. In the study, the researchers utilized 23 samples of shallow ice core drilled in 1995 in Siple Dome, West Antarctica, as part of a National Science Foundation-sponsored ice coring project in the West Antarctic ice sheet. Air was extracted from the samples in Saltzman's laboratory at UCI and analyzed using gas chromatography/mass spectrometry, a powerful analytical technique. "We found trace levels of methyl bromide dating back to the late 1600s in the core's air bubbles," said Saltzman, professor of Earth system science. "This longer-term record of methyl bromide shows convincingly that the amount of methyl bromide in the atmosphere increased during the industrial era. The reconstruction of ancient atmospheric levels of methyl bromide is an exciting development. Ice core records can provide insights into the natural variability of methyl bromide and shed light on how sensitive its atmospheric cycle is to climate change." Previous records of methyl bromide in the atmosphere -- a compilation of instrumental records and firn air measurements -- had only extended back to about the year 1900. (Firn is rounded, well-bonded snow that is older than one year.) The researchers also developed a numerical model to simulate major processes involved in the global biogeochemical cycle of methyl bromide. Both the ice core measurements and modeling results show that human activities such as fumigation, combustion and biomass burning in industrial times have significantly increased atmospheric levels of this gas. "They also highlight the large uncertainty still remaining in our understanding of the modern atmospheric methyl bromide budget," Saltzman said. Methyl bromide is a fumigant used to control insects, nematodes, weeds and pathogens in crops, forests and wood products. Its primary uses are for soil fumigation, postharvest protection and quarantine treatments. The gas also has natural sources in both terrestrial and oceanic environments, as well as natural "sinks" that can remove methyl bromide from the atmosphere. It is the only chemical included in the Montreal Protocol – the international agreement designed to protect the Earth's stratospheric ozone layer – that has major natural sources. Understanding the natural sources and sinks of methyl bromide is a focus of current research, as is gaining a greater understanding of other gases harming the ozone layer, which protects the Earth from ultraviolet radiation. Researchers Murat Aydin of UCI; Warren J. De Bruyn of Chapman University, Orange, Calif.; Daniel B. King of Drexel University, Philadelphia, Pa.; and Shari A. Yvon-Lewis of the National Oceanic and Atmospheric Administration, Miami, Fla., also contributed to the study. The research was supported by the National Science Foundation and the National Oceanic and Atmospheric Administration.

Ozone Holes

March 4, 2004

https://www.sciencedaily.com/releases/2004/03/040304073703.htm

Ocean's Surface Could Have Big Impact On Air Quality, Study Says

COLUMBUS, Ohio – Certain ions bouncing around on the ocean's surface and in droplets formed by waves may play a role in increasing ozone levels in the air we breathe, new research suggests.

These ions cover the surface of the sea in an ultra-thin blanket – about one-millionth the thickness of a sheet of paper. Researchers call this region the "interface." Using a technique that employs highly accurate laser beams, chemists for the first time saw the actual structures formed by these halogen ions, or halides. They could see just how molecules of water surround these ions and also determine the halides' whereabouts within the interfacial area. This kind of information can help researchers predict which halides are more likely to react with other chemicals and ultimately form ozone, a naturally occurring gas which enhances the upper atmosphere's defense against harmful ultraviolet rays. "Interfacial halides have a significant effect on atmospheric chemistry which, in turn, could pose serious implications for respiratory health," said Heather Allen, the study's lead author and an assistant professor of chemistry at Ohio State University. The study appears in the current issue of the Journal of Physical Chemistry – B. Scientists have noted increased ozone levels in urban areas near seawater, and suspect that halides may play a key role. "In marine areas, halides can react with other molecules that form ozone and ultimately increase ozone production in nearby urban areas," Allen said. While the ozone layer in the upper atmosphere is essential for shielding the earth from some solar radiation, high amounts of ozone in the lower atmosphere can cause serious respiratory problems. In a series of laboratory experiments, Allen and her colleagues studied water structures created by three halides commonly found in the marine interfacial zone – chloride, bromide and iodide. The researchers mixed each halide with water to create experimental interfacial zones. They then projected two beams of laser light onto each solution in an attempt to see the structure and location of each halide in the interface. Allen said that while these kinds of pristine interfaces wouldn't be found on the ocean's surface, where many more chemicals are at play, knowing the concentration and structure of interfacial halides could help scientists better understand atmospheric chemistry. "Studying liquid surfaces is difficult," Allen said. "They may look flat, but they're nowhere near flat on a molecular level. The addition of halides and other chemicals alters water's surface structure." When mixed with water, halogen salts become halides – charged particles that, by nature, are unstable and are looking to combine with other elements in order to regain their stability. Two of these halides – iodide and bromide – like to combine with ozone-forming chemicals. "Even though the halides are only one part of the chemical mix in the interface, we didn't really understand how important they were to atmospheric chemistry until we were able to separate out their individual characteristics," Allen said. The researchers found that the concentrations of halides changed deeper into the interfacial layer. Iodide ions favored the surface of the interface, followed by bromide ions. Chloride ions were in abundance in the lower portion of the interface and did not affect the water's surface structure. By virtue of their position in the interface, the iodide and bromide may have a greater impact on the air we breathe. "Iodide turned out to be the most important halide when it came to surface reactions, because it had the highest concentration at the interfacial surface," said Allen, adding that just a little iodide or bromide can influence ozone creation. Chloride appears to be less likely to do so. "Halogens compete with other radicals that are normally used to create ozone," Allen said. "But when enough halogen radicals are available, they actually react faster than do other radicals. She said the next step is to examine the actual reactions between the halides and non-halogen molecules near the sea surface to see if they can actually determine how much ozone is formed and where it's created in greatest quantities. Allen conducted the study with fellow Ohio State researchers Dingfang Liu, Gang Ma and Lori Levering. The team received funding for this work from the National Science Foundation-funded Ohio State Environmental Molecular Science Institute and in part by Research Corporation, based in Tucson, Ariz.

Ozone Holes

February 13, 2004

https://www.sciencedaily.com/releases/2004/02/040212085728.htm

U.S. Push For Diesel Poses Risk To Public Health, Scientists Say

Diesel fuel is now at the center of a delicate balancing act between smog production and global warming. Some lawmakers and car manufacturers advocate widespread diesel use in passenger vehicles as a strategy for reducing the production of so-called "greenhouse gases" thought to cause global warming. But according to a new study, replacing gasoline vehicles in the United States with diesel vehicles - equipped even with the most modern pollution controls - may increase smog production over most of the country.

''If provisions in last year's United States energy bill pass this year, many diesel vehicles will qualify for the same tax credits as hybrid and hydrogen fuel cell vehicles,'' said Mark Jacobson, associate professor of civil and environmental engineering and lead author of the study published January 30 in the journal Geophysical Research Letters. He added, ''It is a surprise to me that this proposal was made before its possible effect on public health was evaluated.'' The main component of smog is ozone. In the upper atmosphere it absorbs intense cancer-causing ultraviolet radiation from the sun and prevents it from reaching Earth. In the lower atmosphere where we breathe, however, ozone is a respiratory irritant associated with decreases in lung function and increases in hospital visits for respiratory causes. Children, the elderly and individuals with preexisting respiratory disease have increased sensitivity to ozone exposure. Ozone is formed in the lower atmosphere through sunlight-initiated chemical reactions between nitrogen oxides and hydrocarbons - compounds found in vehicle exhaust. The U.S. Environmental Protection Agency has designated ozone and nitrogen dioxide, along with four other air pollutants, as ''criteria pollutants'' for setting concentration standards for the protection of public health and the environment. Compared to gasoline-fueled vehicles, diesel-fueled vehicles emit more nitrogen oxides and hydrocarbons, as well as fine particles linked to reduced lung and cardiovascular function. Last year, less than 1 percent of all existing passenger vehicles in the United States were fueled by diesel, but there is an increasing trend toward diesel use. Supporters promote diesel vehicles as obtaining 20 to 30 percent better mileage than do equivalent gasoline vehicles. Such improved fuel efficiency should result in lower emission of compounds that lead to the production of carbon dioxide, a major greenhouse gas. But, according to Jacobson, diesel does not provide a dramatic reduction in carbon emissions. Instead only a modest 5 to 15 percent decrease results. This is because diesel contains more carbon per gallon of fuel than does gasoline. ''Modern'' diesel vehicles do not, however, emit the black, sooty exhaust characteristic of traditional diesel vehicles. This is thanks to better engines, improved fuel mixes and enhanced pollution control technologies such as particle traps and devices for controlling nitrogen oxide emissions. To examine the results of using cleaner diesel technology, Jacobson and his colleagues at the California Institute of Technology, University of Iowa and Argonne National Laboratory used mathematical models to simulate the effects of replacing all gasoline-fueled vehicles in the United States with ''modern'' diesel-fueled vehicles. The scenario was ''best case,'' since diesel vehicles in the United States do not yet have pollution controls such as traps and filters. The researchers programmed data from the extensive U.S. National Emission Inventory into their model. The inventory contains emissions from hundreds of thousands of sources including 1,700 types of vehicle sources, of which 870 types are gasoline. The researchers validated their model by comparing current conditions with observations from the U.S. Ambient Air Quality database. The computer model incorporated all the processes that affect pollution in the atmosphere: emission, gas chemistry, particle processes, meteorology, transport, radiation, clouds, and removal by rainfall and deposition. The main result of the study is that when gasoline vehicles were switched with diesel, there was an increase in surface ozone over 75 percent of the United States, particularly in the Southeast. There was a slight decrease over the remaining 25 percent, but on average, surface level smog increased over the United States. In the lower atmosphere, just above the surface, ozone levels increased across the entire country. In addition, the researchers found that pollutants other than ozone also increased, and confirmed that to reduce ozone levels over most of the United States, controlling vehicular nitrogen oxide emissions would be more effective than controlling hydrocarbon emissions. This is particularly true in the Southeast, where natural vegetation emits high levels of hydrocarbons that react with vehicular nitrogen oxide to form ozone. Jacobson recommended low-emission gasoline-fueled vehicles and high-mileage gasoline-electric hybrid vehicles as the best strategy for reducing vehicle-related air pollution and climate problems simultaneously.

Ozone Holes

February 10, 2004

https://www.sciencedaily.com/releases/2004/02/040210080841.htm

Scientists Find Ozone-Destroying Molecule

Using measurements from a NASA aircraft flying over the Arctic, Harvard University scientists have made the first observations of a molecule that researchers have long theorized plays a key role in destroying stratospheric ozone, chlorine peroxide.

Analysis of these measurements was conducted using a computer simulation of atmospheric chemistry developed by scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The common name atmospheric scientists use for the molecule is "chlorine monoxide dimer" since it is made up of two identical chlorine-based molecules of chlorine monoxide, bonded together. The dimer has been created and detected in the laboratory; in the atmosphere it is thought to exist only in the particularly cold stratosphere over polar regions when chlorine monoxide levels are relatively high. "We knew, from observations dating from 1987, that the high ozone loss was linked with high levels of chlorine monoxide, but we had never actually detected the chlorine peroxide before," said Harvard scientist and lead author of the paper, Dr. Rick Stimpfle. The atmospheric abundance of chlorine peroxide was quantified using a novel arrangement of an ultraviolet, resonance fluorescence-detection instrument that had previously been used to quantify levels of chlorine monoxide in the Antarctic and Arctic stratosphere. "We've observed chlorine monoxide in the Arctic and Antarctic for years and from that inferred that this dimer molecule must exist and it must exist in large quantities, but until now we had never been able to see it," said Dr. Ross Salawitch, a co-author on the paper and a researcher at JPL. Chlorine monoxide and its dimer originate primarily from halocarbons, molecules created by humans for industrial uses like refrigeration. Use of halocarbons has been banned by the Montreal Protocol, but they persist in the atmosphere for decades. "Most of the chlorine in the stratosphere continues to come from human-induced sources," Stimpfle added. Chlorine peroxide triggers ozone destruction when the molecule absorbs sunlight and breaks into two chlorine atoms and an oxygen molecule. Free chlorine atoms are highly reactive with ozone molecules, thereby breaking them up, and reducing ozone. Within the process of breaking down ozone, chlorine peroxide forms again, restarting the process of ozone destruction. "You are now back to where you started with respect to the chlorine peroxide molecule," Stimpfle concluded. "But in the process you have converted two ozone molecules into three oxygen molecules. This is the definition of ozone loss." "Direct measurements of chlorine peroxide enable us to better quantify ozone loss processes that occur in the polar winter stratosphere," said Mike Kurylo, NASA Upper Atmosphere Research Program manager, NASA Headquarters, Washington. "By integrating our knowledge about chemistry over the polar regions, which we get from aircraft-based in-situ measurements, with the global pictures of ozone and other atmospheric molecules, which we get from research satellites, NASA can improve the models that scientists use to forecast the future evolution of ozone amounts and how they will respond to the decreasing atmospheric levels of halocarbons, resulting from the implementation of the Montreal Protocol," Kurylo added. These results were acquired during a joint U.S.-European science mission, the Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone 2000. The mission was conducted in Kiruna, Sweden, from November 1999 to March 2000. During the campaign, scientists used computer models for stratospheric meteorology and chemistry to direct the Earth Resources- 2 aircraft to the regions of the atmosphere where chlorine peroxide was expected to be present. The flexibility of the Earth Resources-2 enabled these interesting regions of the atmosphere to be sampled. For information and images on the Internet, visit: JPL is managed for NASA by the California Institute of Technology in Pasadena.

Ozone Holes

February 9, 2004

https://www.sciencedaily.com/releases/2004/02/040209074236.htm

A Shocking Surprise: High Voltage + Rats = Ozone, Reopens Power-line Debate

RICHLAND, Wash. -- Rats subjected to extreme electromagnetic fields produce dangerous levels of the toxic gas ozone, according to a new study out of the Pacific Northwest National Laboratory that is sure to reenergize the decade-dormant debate about safety around power lines and household appliances.

It is the first experiment to conclusively link an electromagnetic field with a health-adverse chemical effect in the presence of an animal, said Steven Goheen, a scientist at the Department of Energy lab and lead author of a paper published in the current issue of the journal Bioelectromagnetics."All this time, we were looking in the wrong place," Goheen said. "We had been looking inside animals for an effect from the electromagnetic fields. Now it appears that the danger is in the air surrounding animals that are near a large electromagnetic field."Electromagnetic fields are present in devices that use or carry electricity. Goheen and colleagues report that the ozone was produced when rats were present during a "corona discharge," an uncommon phenomenon in which electrons escape from a sharp surface of an electrical conductor at high voltage.The researchers placed rats in a Plexiglas cage hooked up to a device that produced 10 kilovolts, or roughly the power of air ionizers marketed as health aids. In an empty cage, the ozone level peaked at 22 parts per billion with or without a corona discharge. When the animals were present and a centimeter from the corona source – an electrode inserted through the top of the cage – ozone levels were high, more than 200 parts per billion, or double the amount considered toxic at chronic exposure in human beings. The ozone was flushed from the cage quickly for measurements, and the rats were unharmed.The electric field used in the rat experiments is greater than that of a casual passer-by near any high voltage power line, Goheen said, the distance being the key consideration. "Distance was one variable we measured in the rats. When they were more than about 5 centimeters away from the source, we didn't see much effect."This effect should be of concern only to those working much closer to power lines such as linemen or anyone else who spends many hours a day close to high voltage devices. Goheen is quick to note that such workers have more immediate concerns than whiffing a little ozone – such as electrocution and falling.But he notes that if ozone is produced, it is possible that other so-called reactive species may be produced near human beings in the presence of high voltage and that "these results raise new questions about the relationships between electric fields and adverse biological effects."Among the questions Goheen and colleagues are now wrestling with is what, precisely, happens to convert ambient air surrounding an animal's electrified surfaces into its chemical cousin ozone.In an earlier experiment, Goheen measured similar amounts of ozone in grounded water under a corona source, invoking by way of explanation something called "the Taylor cones phenomenon." A liquid surface at high field strength is unstable, with spots of slightly-higher surface charge that protrude from the surface. The tips can elongate and grow so sharp that droplets and even electrons can be ejected.Since most mammals are mostly water and produce surface moisture in sweat glands, saliva and eyes, perhaps here is a connection. Goheen and his co-authors suggest that along with the exposed moist places, "pointed rat whiskers and hairs, as well as ears, nose, and tails, at sufficiently high field strength" contribute somehow to the discharge.###PNNL is a DOE Office of Science research center that advances the fundamental understanding of complex systems and provides science-based solutions in national security, energy, chemistry, the biological sciences and environmental quality. Battelle, based in Columbus, Ohio, has operated PNNL for DOE since 1965.

Ozone Holes

February 5, 2004

https://www.sciencedaily.com/releases/2004/02/040204000415.htm

Scientists Find Ozone-destroying Molecule

WASHINGTON - For years, scientists theorized that a molecule called ClOOCl in the stratosphere played a key role in destroying ozone. Now, using measurements from a NASA aircraft laboratory flying over the Arctic, Harvard scientist Rick Stimpfle and colleagues observed the molecule for the first time. They report their discovery in the Journal of Geophysical Research-Atmospheres, published by the American Geophysical Union.

"We knew from observations dating from 1987, that the high ozone loss was linked with high [levels of] chlorine monoxide, but we had never actually detected the ClOOCl before," Stimpfle said in an interview. The common name atmospheric scientists use for ClOOCl, he said, is "chlorine dimer"--two identical chlorine-based molecules, ClO or chlorine monoxide--bonded together. The rare dimer exists only in the particularly cold stratosphere over polar regions where chlorine monoxide levels are relatively high. "Most of the chlorine in the stratosphere," Stimpfle adds, "continues to come from human-induced sources." ClOOCl triggers ozone destruction, he explains, in three basic steps: 1. ClOOCl absorbs sunlight and breaks into two chlorine atoms and an oxygen molecule.2. The two chlorine atoms react with two ozone molecules, forming two chlorine monoxide molecules and two oxygen molecules.3. The two chlorine monoxide molecules then react with each other to reform ClOOCl."You are now back to where you started with respect to the ClOOCl molecule," Stimpfle says, "but in the process you have converted two ozone molecules into three oxygen molecules. This is the definition of ozone loss." These results were acquired during a joint US-European science mission, SOLVE/THESEO-2000, based in Kiruna, Sweden, from November 1999 to March 2000. A NASA ER-2 aircraft--essentially a U2--flew into Russian air space for the first time with the cooperation of Russian authorities, Stimpfle says, for the purpose of collecting scientific data of interest to the world community. The instrument used to measure ClOOCl was designed to detect several important inorganic chlorine species and was housed in a wing pod of the ER-2. This work was funded by the NASA Upper Atmospheric Research Program.

Ozone Holes

January 6, 2004

https://www.sciencedaily.com/releases/2004/01/040106081225.htm

Ozone Standards Pose Health Risk, Scientists Report

WASHINGTON - The air Americans breathe contains more ozone from pollution than the Environmental Protection Agency estimates, Harvard scientists report. Ozone can cause pain, breathing difficulties, and coughing. It can damage the lungs, EPA warns on its Web site, and it can also make one susceptible to respiratory infections. Those active outdoors are particularly at risk for exposure, the agency says. To calculate air quality standards for ozone, EPA distinguishes between the background or "natural" levels of ozone in the air and that caused by pollution in North America.

"Our results actually indicate that EPA is overestimating the background level, and as a result is underestimating the health risk associated with ozone pollution," atmospheric chemist Arlene Fiore says. This assumption skews the air quality standards that EPA sets, making them weaker than they could be, Fiore and co-authors report in the Journal of Geophysical Research - Atmospheres, published by the American Geophysical Union. Using a three-dimensional model of atmospheric chemistry, the scientists simulated background ozone for the United States and found great variability in ozone, depending upon the season, elevation, and geographic area. "It is highest at high-altitude western U.S. sites in spring," Fiore says. "Results from our modeling study also indicate that frequent springtime high-ozone events, which were previously attributed by some researchers to a natural, stratospheric source, are driven largely by pollution." The big question now for EPA and the scientific community is, according to the researchers, should risk levels of ozone be calculated on a type of sliding scale, depending upon the season and place? "Our answer to [this] question is a resounding yes," Fiore says. "Our modeling study shows that background ozone concentrations in surface air are highly variable, and this variability in background ozone--and its associated risk level--should be taken into account."

Ozone Holes

December 10, 2003

https://www.sciencedaily.com/releases/2003/12/031210073755.htm

Common Airborne Substance Makes Asthmatics More Sensitive To House Dust Mites: Study

CHAPEL HILL -- Exposure to endotoxin, a bacterial substance found commonly in outdoor and indoor air, makes mite-allergic asthmatics more sensitive to house dust and may place them at increased risk of asthma attack.

The new research findings from the University of North Carolina at Chapel Hill School of Medicine are consistent with previous UNC studies showing exposure to ozone to make asthmatics more sensitive to allergens, the environmental triggers of allergic reactions. Both ozone and endotoxin are not allergens; however, they can cause portions of the respiratory tract to become inflamed. The study is published this week in the online December issue of the Journal of Allergy and Clinical Immunology. Endotoxin is a complex of lipids (fats) and sugar molecules that's released through the outer cell wall of common bacteria. When the bacteria die, the cell wall collapses and endotoxin is released into the environment, finding its way into the air and dust. "We know that asthmatics can have asthma attacks triggered by various environmental exposures, but we don't always know why certain circumstances precipitate asthma attacks when there are no clear-cut exposures to the allergens they are sensitized to," said Dr. Brian A. Boehlecke, lead author of the report, professor of medicine in UNC's pulmonary medicine division and member of UNC's Center for Environmental Medicine, Asthma and Lung Biology. "Now it appears that various airborne irritants such as ozone and endotoxin, which can cause airway inflammation, may interact synergistically with other causes of airway problems, including allergens, to make asthma worse," he said. The new study involved 14 participants with mild asthma for whom skin testing showed allergies to house dust mites, one of the most common airborne allergens. Study participants inhaled relatively low levels of endotoxin over four hours that approximated those levels found in some homes and office buildings. Following this exposure, participants underwent an "allergen challenge test." This inhalation test identifies the dose that causes their airways to constrict a specified degree. That dose, once determined for each person, is called their provocation dose, said study co-author Dr. Neil Alexis, assistant professor of pediatrics in the division of allergy, immunology and environmental medicine and a UNC center member. "We found that when allergic individuals breathe endotoxin prior to their allergen challenge, they in fact became more sensitive to the allergen challenge. They were provoked at a lower concentration of allergen compared to previously inhaling air without endotoxin," he said. The findings have implications for air pollution exposure, "in particular those pollutants that cause airway inflammation, which endotoxin does and which ozone does," Alexis said. "So in folks who are already allergic, if they are inhaling pollutants that can further exacerbate their inflammation, it may aggravate the symptoms they normally would have. In other words, they may experience a worsening of their symptoms." Further UNC studies will examine if endotoxin, ozone and other airborne agents share common interactive mechanisms that may increase allergen sensitivity and disease severity in people with asthma. "There is also the possibility of finding drugs to block that interaction and prevent the worsening of asthma," Boehlecke said. Along with Alexis and Boehlecke, UNC co-authors were Drs. Milan Hazucha, Robert Jacobs, Parker Reist, Philip A. Bromberg and David Peden.

Ozone Holes

December 10, 2003

https://www.sciencedaily.com/releases/2003/12/031209080955.htm

The Measure Of Water: NASA Creates New Map For The Atmosphere

NASA scientists have opened a new window for understanding atmospheric water vapor, its implications for climate change and ozone depletion.

Scientists have created the first detailed map of water, containing heavy hydrogen and heavy oxygen atoms, in and out of clouds, from the surface to some 25 miles above the Earth, to better understand the dynamics of how water gets into the stratosphere. Only small amounts of water reach the arid stratosphere, 10 to 50 kilometers (6 to 25 miles) above Earth, so any increase in the water content could potentially lead to destruction of some ozone-shielding capability in this part of the atmosphere. This could produce larger ozone depletions over the North and South Poles as well as at mid-latitudes.Water shapes Earth's climate. The large amount of it in the lower atmosphere, the troposphere, controls how much sunlight gets through to the planet, how much is trapped in our skies, and how much goes back out to space. Higher in the stratosphere, where most of the Earth's ozone shield protects the surface from harmful ultraviolet rays, there is very little water (less than .001 the surface concentration). Scientists don't fully understand how air is dried before it gets to this region.In the troposphere, water exists as vapor in air, as liquid droplets in clouds, and as frozen ice particles in high altitude cirrus clouds. Since there is so much water closer to Earth and so little miles above, it is important to understand how water enters and leaves the stratosphere. The "isotopic content," the natural fingerprint left by the heavy forms of water, is key to understanding the process. An isotope is any of two or more forms of an element having the same or very closely related chemical properties and the same atomic number, but different atomic weights. An example is oxygen 16 versus oxygen 18, both are oxygen, but one is heavier than the other. Heavy water is more readily condensed or frozen out from its vapor, causing the nature of its distribution to differ somewhat from the usual isotopic form of water. A measurement of the isotopic make-up of water vapor enables scientists to determine how water gets into the stratosphere."For the first time, we have water isotope content mapped in incredible detail," said Dr. Christopher R. Webster, a senior research scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. Webster is principal author of a scientific paper announcing the new findings in Science Magazine today. Dr. Andrew J. Heymsfield, of the National Center for Atmospheric Research, Boulder, Colo., is co-author.Measuring water isotopes is extremely challenging, because they represent only a small fraction, less than one percent, of the total water in the atmosphere. Detailed measurements were made using an Aircraft laser Infrared absorption spectrometer (Alias) flying aboard NASA's WB-57F high-altitude jet aircraft in July 2002. This new laser technique enables mapping of water isotopes with sufficient resolution to help researchers understand both water transport and the detailed microphysics of clouds, key parameters for understanding atmospheric composition, storm development and weather prediction."The laser technique gives us the ability to measure the different types of isotopes found in all water," said Webster. "With the isotopic fingerprint, we discovered the ice particles found under the stratosphere were lofted from below, and some were grown there in place."The data help explain how the water content of air entering the stratosphere is reduced, and show that gradual ascent and rapid upward motion associated with tall cloud systems (convective lofting) both play roles in establishing the dryness of the stratosphere.The purpose of the aircraft mission was to understand the formation, extent and processes associated with cirrus clouds. The mission used six aircraft from NASA and other federal agencies to make observations above, in and below the clouds. By combining aircraft data with ground-based data and satellites, scientists have a better picture of the relationship between clouds, water vapor and atmospheric dynamics than previously. They also can better interpret satellite measurements routinely made by NASA.The mission was funded by NASA's Earth Science Enterprise. The Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space. For more information about Alias, visit:For Information about NASA and JPL programs, visit:

Ozone Holes

November 7, 2003

https://www.sciencedaily.com/releases/2003/11/031107060018.htm

Scripps Scientists Link Ozone To Atherosclerosis

A team of investigators led by The Scripps Research Institute (TSRI) President Richard A. Lerner, M.D., and TSRI Associate Professor Paul Wentworth, Jr., Ph.D., are reporting evidence for the production of ozone in fatty atherosclerotic plaques taken from diseased arteries.

Lerner is Lita Annenberg Hazen Professor of Immunochemistry and holds the Cecil H. and Ida M. Green Chair in Chemistry at TSRI. He is also one of several scientists on the team who are members of The Skaggs Institute for Chemical Biology at TSRI. Lerner, Wentworth, and their colleagues have been looking at the production of ozone molecules within the human body for the last year and a half, ever since they made the completely unexpected discovery that human antibodies generate a product with the chemical signature of ozone. Ozone is a highly reactive molecule that has never before been considered part of biology. So if antibodies produce ozone in the human body, the TSRI scientists asked, what is the ozone doing there? Their report, out in this week's issue of the journal Science, details what they found. In their report, Lerner, Wentworth, and their colleagues describe how ozone can trigger pathological changes in other molecules in the body, like cholesterol, which ozone breaks down to produce toxic compounds. The scientists describe two such compounds, which they call the "atheronals." These atheronals were found in atherosclerotic plaques that were surgically removed from patients with atherosclerosis. The scientists suggest these newly identified products are critical to the pathogenesis of atherosclerosis because they are toxic to white blood cells, smooth muscle cells, and cells from the arterial walls--all the major types of cells in and around atherosclerotic plaques. Furthermore, they suggest that atheronals and similar products of ozonolysis may contribute to a number of other diseases, such as lupus, multiple sclerosis, and rheumatoid arthritis. "Ozone is damaging, and it is really a problem that we are going to have to think about in the next few years," says Wentworth. "There may be a whole slew of molecules that ozone generates that we have never thought about before." Finally, Lerner, Wentworth, and their colleagues detail how one of the atheronals was found in the blood of patients who have late-stage atherosclerosis, but not in healthy individuals. This suggests that the presence of atheronals may be a good indicator of late-stage arterial inflammation--perhaps the basis for a diagnostic test for atherosclerosis. Currently, physicians use other risk factors to identify a patient's risk: elevated cholesterol, hypertension, diabetes, smoking, obesity and a family history of vascular disease at an age less than 55. These indicators are not always reliable, and there is a substantial fraction of patients who develop atherosclerosis without displaying these risk factors. Sensitive diagnostic markers that would allow early identification of patients at risk of life-threatening atherosclerosis would be a boon to preventative medicine. Atherosclerosis and Ozone Atherosclerosis is a common vascular disease that increases the risk of heart attacks and strokes. In fact, heart disease is the most common cause of death in the United States. The Centers for Disease Control and Prevention statistics for 2000 list 878,471 deaths from heart disease and stroke, followed by 553,091 for cancer. The name of the disease comes from the Greek athero (which means gruel or paste) and sclerosis (which means hardness). And, as the name implies, it is a disease that is characterized by a hardening of the arteries over time due to the buildup of hard plaques--fibrous tissue, calcium, fat, cholesterol, proteins, cells, and other materials--on the inner "endothelial" walls of an artery. These plaques feel something like cartilage to the touch, which explains why atherosclerosis is commonly called hardening of the arteries. Over the last few years, evidence has been accumulating that the process of atherosclerosis has a significant inflammatory component. Given this evidence, Lerner, Wentworth and their colleagues thought they would look at tissue involved in the disease for evidence of ozone. Ozone is a particularly reactive form of oxygen that exists naturally as a trace gas in the atmosphere, constituting on average fewer than one part per million air molecules. The gas plays a crucial role in protecting life on earth from damaging solar radiation by concentrating in the upper reaches of Earth's stratosphere--about 25 kilometers above the surface--and absorbing ultraviolet radiation. Ozone is also a familiar component of air in industrial and urban settings where the highly reactive gas is a hazardous component of smog in the summer months. A few years ago, Lerner and Wentworth made the completely unexpected discovery that ozone is involved in human biology. Lerner and Wentworth realized that atherosclerotic plaques have all the ingredients needed to make ozone. They contain white blood cells, which have the ability to generate the singlet oxygen that the antibodies need to produce ozone--and plenty of antibodies passing by in the blood stream. Ozone Present in Atherosclerotic Plaques Last year, Lerner and Wentworth approached Giacomo DeLaria, M.D., who is a vascular surgeon at nearby Scripps Clinic, and asked if they could obtain samples of carotid atherosclerotic plaques. DeLaria provided a sample of plaque material from a patient who recently underwent an endarterectomy, generously enabling Wentworth, Lerner, and their colleagues to perform their studies. Endarterectomies are common surgical procedures to remove plaques from the inner walls of atherosclerotic arteries. "These are specimens we normally just inspect and throw away," says DeLaria, who is a coauthor of the study. "Within themselves, they have no diagnostic value, and they don't change what we do after the procedure." Wentworth and Lerner tested this sample, and the results proved promising. They found some abnormalities that could be associated with the presence of ozone in these plaques. But they wanted to be sure. So DeLaria and his fellow vascular surgeon Ralph Dilley, M.D., provided several more samples. When Lerner, Wentworth, and their colleagues studied the atherosclerotic plaque samples, they found the evidence they were looking for. The atheronals--signature products that were produced when the highly reactive ozone mixed with cholesterol--were evident in the plaques. This suggests that ozone production occurred as these plaques were being formed. ###The article, "Evidence for Ozone Formation in Human Atherosclerotic Arteries" is authored by Paul Wentworth Jr., Jorge Nieva, Cindy Takeuchi, Roger Galve, Anita D. Wentworth, Ralph B. Dilley, Giacomo A. DeLaria, Alan Saven, Bernard M. Babior, Kim D. Janda, Albert Eschenmoser, and Richard A. Lerner. The article will be published in the November 7, 2003 issue of the journal Science, and it will be available online to Science subscribers this week at:

Ozone Holes

November 6, 2003

https://www.sciencedaily.com/releases/2003/11/031104063134.htm

Near-real Time Ozone Forecasting Made Possible By Envisat

Stratospheric data supplied by Envisat are the basis for a near-real time global ozone forecasting service now available online.

Up in the stratosphere about 25 km above our heads is the ozone layer. Stratospheric ozone absorbs up to 98% of the Sun's harmful ultraviolet light – making the difference between a suntan and sunburn, and safeguarding all life on Earth. But chemical activity in the stratosphere ultimately due to the presence of manmade gases such as chlorofluorocarbons (CFCs) can thin the ozone layer. The Brussels-based Belgian Institute for Space Aeronomy (BIRA-IASB from its initials in Flemish and French) has developed a service called the Belgian Assimilation System of Chemical Observations from Envisat (BASCOE) that maps and forecasts not only the concentration of ozone in the stratosphere but also 56 other chemical species, including those responsible for ozone depletion. BASCOE relies on an instrument aboard Envisat called the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). It works day and night to measure infrared emissions from the Earth's 'limb' – the narrow band of atmosphere between the planetary surface and empty space. Emissions along certain wavelengths work like signatures, indicating the presence of specific atmospheric chemicals. MIPAS has the capability to measure up to 30 trace gas species, but for the time being only a subset of them is provided by the ESA ground segment operationally to the user community. The others whose concentrations are forecast by BASCOE have their presence calculated indirectly, by assimilating MIPAS level 2 products into a complex computer model of stratospheric chemistry processes developed by BIRA-IASB. The resultant analyses are available within a day. "The stratosphere is one of the best-understood areas of atmospheric chemistry, a fact which makes the BASCOE model possible," explained Dominique Fonteyn of BIRA-IASB. "In fact this model predates the launch of Envisat, and was originally intended simply as a summary of our existing understanding of stratospheric chemistry. But the large amount of work that went into it – some 50,000 lines of code – made us look at using it in other ways, and assimilating Envisat data into it for operational use. "The aim was to reduce the usual time delay between satellite observation and data use, in the same way weather forecasting does. As well as chemical interactions, the model also includes weather data provided by the European Centre for Medium Range Weather Forecasts, because polar stratospheric clouds transported by winds play a major role in the process of ozone destruction." Users of the service – available at The intention to use the MIPAS data to 'fine-tune' the model in future for increased accuracy, along with assimilating data from other Envisat instruments such as GOMOS (Global Ozone Monitoring by Occultation of Stars) and SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) once they become available.

Ozone Holes

October 16, 2003

https://www.sciencedaily.com/releases/2003/10/031016064211.htm

New Global Treaty Proposed To Control Climate Change And Improve Health

A global treaty focusing on intercontinental air pollution could be a better approach to controlling climate change than the Kyoto Protocol, according to a new scientific study. By cooperating to reduce pollutants like ozone and aerosols, countries could address their own regional health concerns, keep their downwind neighbors happy and reduce the threat of global warming in the process, claim the researchers.

The report appears in the Oct. 13 edition of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society. The Kyoto Protocol, drafted in 1997, was designed to provide binding commitments for reducing national emissions of greenhouse gases, with a special emphasis on carbon dioxide. Some countries, however, like the United States and China, have been reluctant to fully adopt the standards because of their potential economic burden. In the new study, researchers from Columbia (N.Y.), Harvard and Princeton acknowledge the need to regulate carbon dioxide emissions, but they propose that a treaty dealing with air pollutants like ozone and aerosols, which can cause health problems, could be a better first step, uniting the interests of all countries involved. "We suggest that it may be time to consider an international treaty to control air pollution on a hemispheric scale," says lead researcher Tracey Holloway, Ph.D. "The Kyoto Protocol addresses carbon dioxide emissions, which have no direct health impact, so they are not regulated currently as air pollutants." Holloway was at Columbia University when the study was done and is now with the University of Wisconsin-Madison. An air pollution treaty that targets health-related pollutants "would tie in to regulations that most countries are already pursuing on a domestic basis," according to Holloway. One obvious example of this in the United States is the Clean Air Act, which regulates various pollutants, such as those that contribute to acid rain, smog and ozone depletion. Holloway and her colleagues focused their research on ozone and aerosols. Both have lifetimes of about one week - long enough to be transported from Asia to the United States, as well as shorter distances across the Atlantic - and both pose health risks associated with respiratory disease, which Holloway says makes them more immediate concerns to countries than carbon dioxide. But ozone and aerosols also contribute to large-scale climate problems, Holloway says, so the implications of controlling them go beyond air pollution into the realm of climate change. The case for controlling greenhouse gases other than carbon dioxide was first presented three years ago by James Hansen of NASA's Goddard Institute for Space Studies, according to Holloway. Holloway believes an international air pollution treaty would not encounter the roadblocks that the Kyoto Protocol has faced. "It would be serving the self-interest of participating countries to address short-term health risks," she says. "Regulation could take shape without immediate reform of the domestic or international energy economy, and energy savings implemented to achieve air quality goals could have the win-win effect of reducing carbon dioxide emissions as well." Holloway suggests a treaty based loosely on the 1979 Convention on Long-Range Transboundary Air Pollution (LRTAP), which initially addressed acid rain deposition in Europe through voluntary participation. The convention has since been amended to cover a broad range of pollutants, and participants include countries from Western and Eastern Europe as well as the United States and Canada. Expanding such a treaty to include Asia would give the United States even more incentive to participate, Holloway says, since westerly winds spread pollution from that part of the world to North America. "Asian countries are already concerned about air pollution," she adds, "and are making significant strides toward domestic control."

Ozone Holes

October 16, 2003

https://www.sciencedaily.com/releases/2003/10/031016063501.htm

Down And Dirty: Airborne Ozone Can Alter Forest Soil

HOUGHTON, Mich. -- The industrial pollutant ozone, long known to be harmful to many kinds of plants, can also affect the very earth in which they grow.

Researchers at Michigan Technological University and the North Central Research Station of the USDA Forest Service have discovered that ozone can reduce soil carbon formation--a measure of the amount of organic matter being added to the soil. Their findings are published in the Oct. 16 issue of the journal Nature.The scientists exposed forest stands to increased levels of two atmospheric pollutants, ozone and carbon dioxide. Soil carbon formation dropped off dramatically in the plots fumigated with a mix of ozone and carbon dioxide compared to carbon dioxide alone."This research shows that changes in atmospheric chemistry can cascade through the forest and affect soils," says Dr. Kurt Pregitzer, a coauthor of the Nature paper and a professor in Michigan Tech's School of Forest Resources and Environmental Science. "Reductions we have observed in plant growth under elevated ozone appear to result in similar reductions in soil carbon formation."The findings could have implications for the health of forests in areas with high levels of ozone, says Dr. Wendy Loya, the lead author of the paper and a postdoctoral research scientist at Michigan Tech. "Under normal conditions, forest litter, which is made up of fallen leaves, twigs and dead roots, decomposes and releases carbon that is then stored in the soil," she says. "Under conditions of elevated ozone, the amount of soil carbon formed is reduced."Because increased carbon dioxide tends to cause plants to grow more quickly and take in more carbon from the atmosphere, some scientists and policymakers have speculated that forests could become "carbon sinks," absorbing carbon dioxide and mitigating its greenhouse effects.However, the soil in the plots exposed to an ozone/carbon dioxide mixture gained only half the carbon as plots fumigated with carbon dioxide alone. Thus, plants and soils may be less able to clean the air of excess carbon dioxide when ozone levels are high.Ozone pollution occurs at levels known to be toxic to both plants and people in many parts of the United States and throughout the world. It is formed when chemicals produced by burning fossil fuels and from industrial processes react in the presence of sunlight and warm temperatures.In addition to Loya and Pregitzer, other coauthors of the Nature article, "Reduction of Soil Carbon Formation by Tropospheric Ozone Under Elevated Carbon Dioxide," are Dr. John King, an assistant professor of ecosystems at Michigan Tech; and research ecologist Dr. Christian Giardina and ecologist Noah Karberg of the USDA Forest Service.This research was supported by the US Department of Energy's Office of Science (BER: Program for Ecosystem Research and National Institute for Global Environmental Change), the USDA Forest Service (Northern Global Change and North Central Research Station), the National Science Foundation (DEB, DBI/MRI), and the USDA Natural Research Initiatives Competitive Grants Program.The four-year study was conducted at Aspen FACE (Free-Air CO2 Enrichment), the world's largest, open-air climate-change research facility. Located in Rhinelander, Wis., Aspen FACE opens a window on the future of our northern forests and is the only FACE site where scientists can study the impact of the greenhouse gases carbon dioxide and ozone on forest ecosystems. For more information on Aspen FACE, contact its director, Dr. David Karnosky, Aspen FACE is funded jointly by the Department of Energy's Office of Science Program for Ecosystem Research and National Institute for Global Environmental Research; the National Science Foundation; Global Change Program, USDA Forest Service; North Central Research Station, USDA Forest Service; Michigan Technological University; the USDA National Research Initiative Program; Brookhaven National Laboratory; and Natural Resources Canada.

Ozone Holes

October 14, 2003

https://www.sciencedaily.com/releases/2003/10/031014072546.htm

UC Scientists Discover Plant Gene That Promotes Production Of Ozone-destroying Methyl Halides

A team of University of California scientists has identified a gene that controls the production by terrestrial plants of methyl halides, gaseous compounds that contribute to the destruction of ozone in the stratosphere.

The discovery of the gene, detailed in the October 14 issue of the journal Current Biology, is important because it now provides scientists with a genetic tool with which to probe how and why plants produce methyl halides. The identification of the gene should also help researchers determine the extent to which plants emit methyl halides into the atmosphere and why certain plants increase their methyl halide emissions in high salt environments. The team of plant geneticists at UC San Diego and atmospheric chemists at UC Irvine dubbed the gene HOL for "Harmless to Ozone Layer" because disruption of the gene largely eliminates methyl halide production. The researchers discovered the gene in Arabidopsis, a mustard plant in the cabbage family that is used commonly in genetic studies. The researchers also found closely related variants, or homologues, of the HOL gene in the genetic databases of rice, cotton, corn and barley. Homologues had been identified separately in cabbage and a salt marsh plant by geneticists at the University of Montreal and the University of Illinois, Urbana-Champaign, respectively. These discoveries, taken together, indicate that the gene is likely a common trait of all terrestrial plants. However, the scientists emphasize that the ubiquity of the HOL gene in plants and their results cannot be used to suggest that plants are responsible for the depletion of the earth's ozone layer. "Stratospheric ozone depletion is a human-created problem," says Robert C. Rhew, an assistant professor of geography at UC Berkeley who noted that most of the bromine and chlorine that reach the stratosphere are produced by humans. "Methyl halides are tricky compounds to study because they emanate from both natural and human sources, and our study addresses the current pressing question of how and why these methyl halides are produced." Rhew conducted the study while a postdoctoral researcher in the laboratory of Eric S. Saltzman, a professor of earth system science at UC Irvine who is also a co-author. "The take-home message of this study is that all plants probably have this gene," says Lars Østergaard, a postdoctoral researcher in the laboratory of Martin Yanofsky, a UCSD biology professor and a co-author. "Now we can determine more precisely the impact plants have on the production of methyl halides and whether it might be appropriate or feasible to engineer crops to minimize the expression of this gene." Østergaard and Yanofsky began their collaboration with the UC Irvine chemists several years ago, when Rhew, a former graduate student at UCSD's Scripps Institution of Oceanography working on identifying natural sources of methyl halides, wondered if a plant gene could be found that controlled methyl halide production. Human-produced compounds that release chlorine and bromine into the atmosphere-such as chlorofluorocarbons (CFCs), halons and industrially produced methyl bromide-have long been identified as stratospheric ozone depleting compounds and are gradually being phased out under the 1987 Montreal Protocol in an effort to reduce the halogen load in the atmosphere. But a number of studies in recent years have found that some crops also contribute to the atmosphere a small fraction of ozone-reacting methyl halides, such as methyl chloride, methyl iodide and methyl bromide-a compound that is manufactured to be used in agriculture as a soil fumigant, but which will be phased out completely by the Montreal Protocol by 2005. One such study published in Science three years ago by a UC Irvine team estimated, from measurements of a rice paddy over a period of two years, that rice farming around the world contributes 1 percent of the total methyl bromide and 5 percent of the methyl iodide emissions. "The major industrial sources of these halides increasingly are being regulated, but we still must uncover their natural sources," says UCI Chancellor Ralph J. Cicerone, a leading expert on ozone depletion who headed the Science study. "We only know where half of the methyl chloride and two-thirds of the methyl bromide are coming from. The identification of the HOL gene is a critical step forward in allowing us to determine more precisely the contribution of plants to these unknown, natural sources of methyl halides." Another study, published by Rhew while a graduate student at Scripps, estimated that 10 percent of the natural global emissions of methyl chloride and methyl bromide could be coming from salt marshes, which make up less than a tenth of one percent of the global terrestrial surface area. Other studies have identified biomass burning, leaded gasoline combustion, fungi and the oceans as primary sources of methyl halides. Scientists have discovered that as the concentration of salts, or halides, increase in the soil or water, plants tend to release more of those methyl halides into the atmosphere. This suggests that the current push to generate new varieties of salt-tolerant crops to increase food production may have the unintended effect of increasing methyl halide emissions. The University of California team discovered that the HOL gene controls the production of an enzyme that catalyzes the production in plants of methyl bromide, methyl chloride and methyl iodide. The scientists found that the addition of bromide salts to a substrate on which their Arabidopsis plants grew led to a more than a thousand-fold increase in methyl bromide. But plants with a mutant, non-working copy of the HOL gene, the scientists discovered, produced only 15 percent of the methyl chloride, 4 percent of the methyl bromide and 1 percent of the methyl iodide of normal, wild-type plants. The UC scientists say the enzyme produced by the HOL gene may function to metabolize plant compounds that are thought to serve as insect repellents, suggesting that plants may have initially evolved the biochemical pathway that produces methyl halide emissions to ward off insects. This may provide an additional challenge to scientists seeking to genetically engineer salt tolerant crops that can minimize methyl halide production without losing their natural insect resistance. "By studying plants with normal and mutant copies of this gene," says Yanofsky of UCSD, "we should be able to address the question of whether the gene is important for pathogen resistance." The study was supported by grants from the National Science Foundation and NOAA's Postdoctoral Program in Climate and Global Change.

Ozone Holes

October 7, 2003

https://www.sciencedaily.com/releases/2003/10/031007054719.htm

UCI Study Uncovers Unexpectedly High Air Pollutant Levels In Southwest States

Irvine, Calif. -- UCI atmospheric scientists have found that greenhouse gases released from oil and natural gas exploration and processing in Oklahoma, Texas and Kansas create regional air pollution levels similar to those found in large urban centers elsewhere in the United States.

F. Sherwood Rowland, Donald R. Blake and colleagues sampled ground-level hydrocarbon gases through a 1,000 mile-wide swath of the central and southwest regions of the United States in late 2001 and early 2002. They recorded levels of various hydrocarbons -- including methane, ethane, propane and butane -- in and around Oklahoma City that equaled or surpassed those in such high-smog cities as Los Angeles, Houston, New York and Chicago. These hydrocarbons participate in the formation of ground-level ozone, a major component in smog that contributes to lung ailments in children. Study results appear in the Online Early Edition of the Proceedings of the National Academy of Science the week of Oct. 6, 2003. (www.pnas.org) "Based on these findings, it appears that the U.S. is emitting four to six million tons more methane per year than previously estimated," said Rowland, a Nobel laureate in chemistry and one of the world's leading experts on global air pollution. "In fact, our study suggests that total hydrocarbon emissions are higher than stated in current estimates. This means the American air pollution problem has still another new, significant aspect." In their study, Rowland and Blake recorded high pollution levels in Texas, Oklahoma and southwestern Kansas. These regional levels correlated with the locations of the oil and natural gas refineries concentrated in these areas. The UCI researchers then compared atmospheric hydrocarbon levels in Oklahoma City and a dozen other U.S. cities. They discovered that the air in and around the Oklahoma capital contained more than double the amounts of ethane, propane and butane than the air in more congested urban areas. They also found elevated amounts of methane -- a gas that in the past half century is regarded second only to carbon dioxide as a root cause of the greenhouse effect. In addition, their samples revealed ample amounts of alkyl nitrates. These chemicals are byproducts of the atmospheric reactions involving hydrocarbons that lead to the formation of ozone, a major component of urban smog. The alkyl nitrates are reliable markers of ozone formation and were found at levels higher than in most urban environments. "Our group found these higher hydrocarbon levels over the area incorporating the largest natural gas and oil reserves in the continental U.S.," Rowland said. "Similar studies of natural gas and oil regions in other countries would help better monitor global emission of greenhouse gases such as methane which contribute to air pollution and overall climate change." In addition to this Oklahoma City study, Rowland and Blake have studied the air content in high-smog cities such as Mexico City; Karachi, Pakistan; Santiago, Chile; and other areas around the world to help local governments improve their air quality. UCI chemists Aaron S. Katzenstein, Lambert A. Doezema and Isobel J. Simpson assisted Rowland and Blake on this study. It was funded by the National Institute for Global Environmental Change, a division of the U.S. Department of Energy. The University of California, Irvine is a top-ranked public university dedicated to the principles of research, scholarship and community. Founded in 1965, UCI is among the fastest-growing University of California campuses, with more than 24,000 undergraduate and graduate students and about 1,300 faculty members. The third-largest employer in dynamic Orange County, UCI contributes an annual economic impact of $3 billion. A complete archive of press releases is available on the World Wide Web at

Ozone Holes

September 26, 2003

https://www.sciencedaily.com/releases/2003/09/030926070725.htm

2003 Ozone 'Hole' Approaches, But Falls Short Of Record

This year's Antarctic ozone hole is the second largest ever observed, according to scientists from NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Naval Research Laboratory.

The Antarctic ozone hole is defined as thinning of the ozone layer over the continent to levels significantly below pre-1979 levels. Ozone blocks harmful ultraviolet "B" rays. Loss of stratospheric ozone has been linked to skin cancer in humans and other adverse biological effects on plants and animals.The size of this year's hole reached 10.9 million square miles on September 11, 2003. It was slightly larger than the North American continent, but smaller than the largest hole ever recorded, on September 10, 2000, when it covered 11.5 million square miles. Last year the ozone hole was smaller, covering 8.1 million square miles. NASA's Earth Probe Total Ozone Mapping Spectrometer and the NOAA-16 Solar Backscatter Ultraviolet instrument provided ozone measurements from space. These data were coupled with data collected by NOAA's Climate Monitoring and Diagnostics Laboratory (CMDL) from balloon-borne instruments, which measure the ozone hole's vertical structure. NASA's own scientist Paul Newman said, "While chlorine and bromine chemicals cause the ozone hole, extremely cold temperatures, especially near the edge of Antarctica, are also key factors in ozone loss." Given the leveling or slowly declining atmospheric abundance of ozone-destroying gases, the year-to-year changes in the size and depth of the ozone hole are dominated by the year-to-year variations in temperature in this part of the atmosphere. The fact this year's ozone loss is much greater than last year's reflects the very different meteorological conditions between these two years. NASA scientist Rich McPeters said ozone observations showed the total amount of ozone from surface to space was 106 Dobson Units (DU) on September 14, 2003, the minimum value reached this year. "Dobson units" measure the "thickness" of protective ozone in the stratosphere. They range from 100 DU to 500 DU, which translate to about 1 millimeter (1/25 inch) to 5 millimeters (1/5 inch) of ozone in a layer. Bryan Johnson of CMDL said the ozone depletion region, from 7-to-14 miles above the Earth, has large losses, similar to losses seen in the 1990s. If the stratospheric temperature remains cold over the pole, then we should see complete ozone loss in the 9-13 mile layer, with total column ozone reaching 100 DU by early October.The Montreal Protocol and its amendments banned chlorine-containing chlorofluorocarbons (CFCs) and bromine-containing halons in 1995, because of their destructive effect on the ozone. However, CFCs and halons are extremely long-lived and still linger at high concentrations in the atmosphere. However, the atmospheric abundances of ozone destroying chemicals are beginning to decline. As a result, the Antarctic ozone hole should disappear in about 50 years. NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space. For more information and images on the Internet, visit:NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of our nation's coastal and marine resources. To learn more about NOAA, visit:

Ozone Holes

July 30, 2003

https://www.sciencedaily.com/releases/2003/07/030730080139.htm

Destruction Of Ozone Layer Is Slowing After Worldwide Ban On CFC Release

WASHINGTON - The rate at which ozone is being destroyed in the upper stratosphere is slowing, and the levels of ozone-destroying chlorine in that layer of the atmosphere have peaked and are going down -- the first clear evidence that a worldwide reduction in chlorofluorocarbon pollution is having the desired effect, according to a new study.

"This is the beginning of a recovery of the ozone layer," said Professor Michael Newchurch of the University of Alabama in Huntsville (UAH), the scientist who led the ozone trend-analysis research team. "We had a monumental problem of global scale that we have started to solve." Using data from three NASA satellites and three international ground stations, the team found that ozone depletion in the upper stratosphere -- the layer of the atmosphere between 35 and 45 kilometers [22-28 miles] above the ground -- has slowed since 1997. "We are extremely pleased to have the highly calibrated, long term satellite and ground-based data records necessary to observe these small, but important changes in the ozone layer," said Newchurch. The results of this work have been accepted for publication in the American Geophysical Union's Journal of Geophysical Research - Atmospheres. Ozone is a damaging pollutant in the lower atmosphere near the ground, but in the stratosphere, it shields the Earth from harmful ultraviolet solar radiation. Almost 30 years ago, scientists Mario Molina, F. Sherwood Rowland, and Paul Crutzen showed that chlorine released into the stratosphere from chlorofluorocarbons (CFC), chemicals used as refrigerants and aerosol propellants, was destroying the protective ozone layer. This discovery led to an international ban on CFC-based products and to the 1995 Nobel Prize in Chemistry for the three scientists. "There have been several amendments to that ban, each of which tightened restrictions on CFCs and other halogenated hydrocarbons," said Newchurch, an associate professor of atmospheric science at UAH. "We are now at the point where the restrictions are tight enough to result in measured turnaround of CFC amounts at the surface. Now, we can say that what we're doing is working, and we should continue the ban. "We're not gaining ozone, we're just losing it less quickly. But the trend line is flattening. And the amount of chlorine in that layer of the stratosphere has not yet peaked, but has slowed down significantly, so we should start to see some ozone improvement in the coming years," he said. The slowing of ozone destruction is seen only in the upper stratosphere, where ozone depletion is due primarily to chlorine pollution, Newchurch said. "But there's not much ozone up there, and it has a small effect on the total ozone column. We don't see compelling evidence that the destruction of ozone is slowing in the lower stratosphere, where 80 percent of the protective ozone layer exists." Many factors, including chlorine levels, influence ozone depletion in the lower stratosphere, the layer of atmosphere between about 20 and 35 kilometers [16-22 miles] up. "Fixing the chlorine problem is never, by itself, going to solve the lower stratosphere problem," Newchurch said. "There are many things that push the lower stratosphere." One of those things is the concentration of greenhouse gases, such as carbon dioxide and methane. While these gases warm the lower atmosphere, they cool the stratosphere by radiating heat out to space. Cooling the stratosphere has both good and bad effects on ozone destruction, Newchurch said. Cooling the air in the upper stratosphere slows the rate of chemical destruction reactions, thereby increasing the ozone amounts. In the lower stratosphere, cooling also changes wind and air mixing patterns in a way that can increase ozone depletion, especially in high latitudes. Newchurch's co-investigators included Eun-Su Yang, now at the Georgia Institute of Technology, Derek M. Cunnold at Georgia Institute of Technology, Gregory Reinsel at the University of Wisconsin, Joseph M. Zawodny at NASA's Langley Research Center, and James Russell at Hampton University. They analyzed satellite measurements of ozone, hydrogen chloride, and greenhouse gases, along with ground-based measurements of ozone and solar activity. "As the satellites orbit Earth, they see a sunset and a sunrise once every 90-minute orbit," Newchurch said. "The instruments look at the Sun as it sets or rises, as the sunlight is filtered through the atmosphere. Because ozone and other constituents absorb light at known wavelengths, we can measure how much light at those wavelengths is coming through the atmosphere and calculate from that the amount of ozone and other gases." The team used data from three NASA Earth-observing satellites: SAGE 1, which operated from 1979 through 1981; and SAGE II, which went into orbit in October 1994, and the HALOE instrument aboard NASA's UARS satellite, launched in 1991, which are still operating. "SAGE and HALOE instruments both look at the atmosphere, but they have very different techniques and are on different satellites," said Newchurch. "The fact that they both see the same trend in the ozone and see the same trend as the ground-based instruments is very compelling evidence that they are both right." Released into the atmosphere, CFC molecules will take several years to "percolate" upward into the stratosphere. As they rise, ultraviolet light them breaks up, releasing the chlorine. This free chlorine reacts with ozone, converting two ozone molecules into three oxygen molecules. Eventually, most of the chlorine bonds with hydrogen atoms to form nearly inert hydrogen chloride, which over a period of years drifts into the lower atmosphere. There, it dissolves into water vapor and is rained out of the atmosphere. The entire process takes decades," Newchurch said.

Ozone Holes

July 29, 2003

https://www.sciencedaily.com/releases/2003/07/030728080920.htm

Increasing Carbon Dioxide Relieves Drought Stress In Corn, Researchers Say

CHAMPAIGN, Ill. -- Increasing carbon dioxide in the atmosphere will benefit photosynthesis in U.S. corn crops in the future by relieving drought stress, say researchers at the University of Illinois at Urbana-Champaign. According to preliminary findings of a new study -- being released this week in Hawaii during Plant Biology 2003, the annual meeting of the American Society of Plant Biologists -- photosynthesis of maize on average increased by 10 percent under projected carbon dioxide conditions in the year 2050.

"Carbon dioxide in isolation is good news for the farmers, but unfortunately such conditions won't be in isolation from other factors, so it isn't known how significant these findings may be," said Stephen P. Long, a professor of plant biology and crop sciences. Long is a lead researcher of SoyFACE (Free Air Concentration Enrichment), a long-term project and the only open-air experiment in the world looking at the effect of future levels of ozone and carbon dioxide gases on agricultural crops. The corn photosynthesis findings are being exhibited by Andrew Leakey, a Fulbright scholar from Scotland who is conducting research in the SoyFACE fields with Long and with Carl Bernacchi and Donald Ort, both professors of plant biology at Illinois and scientists with the USDA/Agricultural Research Service. Corn is among the 1 percent of plants that use the carbon-dioxide efficient photosynthesis system known as C4. Scientists had theorized that C4 plants would not respond to more carbon dioxide in the air, because the gas is internally concentrated by the leaf – essentially a fuel-injected photosynthesis, Leakey said. However, Leakey found that in a carbon dioxide concentration of 550 parts per million, carbon fixation in the leaves indeed rose in association with greater intercellular carbon dioxide and enhanced water use efficiency. The 2002 growing season, when the research was conducted, was considered a typical one in terms of weather. However, at the end of a dry spell in June, Leakey found, carbon fixation increased under elevated carbon dioxide as much as 41 percent. Since carbon dioxide serves to close the stomata, which are tiny pores in the epidermal layer of leaves, the jump in photosynthesis likely resulted from the plant maintaining higher water content in the leaves during the dry period, Long said. The improvement in corn growth could be offset by the effects of rising ozone levels and other global warming factors, the researchers are quick to point out. While elevated ozone is part of the SoyFACE technology, corn has not yet been exposed to it. In soybeans, initial exposure to carbon dioxide led to increased yields that were later dramatically reversed by the effects of ozone. The SoyFACE research area on the south end of campus features 70-foot octagon-shaped plots in which ABS plastic pipes deliver at crop level a precisely regulated flow of either carbon dioxide and/or ozone from 50-ton solar-powered tanks. Control rings surround equal amounts of control crops, which grow in normal conditions, without gases, for comparison purposes. Construction began in 2000; research began the next spring. SoyFACE comprises more than 30 research groups with participants from 18 countries. Funding is provided by the Illinois Council for Food and Agricultural Research, the U.S. Department of Agriculture, the International Arid Lands Consortium of Astra-Zeneca, United Kingdom, the U.S. Department of Energy's Argonne National Laboratory, Archer Daniels Midland Co. and Pioneer Hi-Bred International Inc.

Ozone Holes

July 28, 2003

https://www.sciencedaily.com/releases/2003/07/030725082308.htm

Scientists Find 'Fingerprint' Of Human Activities In Recent Tropopause Height Changes

LIVERMORE, Calif. -- Scientists from the Lawrence Livermore National Laboratory have determined that human-induced changes in ozone and well-mixed greenhouse gases are the primary drivers of recent changes in the height of the tropopause.

Earlier research has shown that increases in the height of the tropopause over the past two decades are directly linked to stratospheric ozone depletion and increased greenhouse gases. The new research uses climate model results to provide more quantitative estimates of the relative contributions of natural and human influences to overall tropopause height changes. This work indicates that 80 percent of the roughly 200-meter increase in tropopause height from 1979 to 1999 is directly linked to human activities. Smaller tropopause height increases over the first half of the 20th century are largely caused by natural variations in volcanic aerosols and solar irradiance. The tropopause is the boundary between the lowest layer of the atmosphere -- the turbulently mixed troposphere -- and the more stable stratosphere. It lies roughly 10 miles above the Earth's surface at the equator and five miles above the poles. The location of the tropopause is sensitive to changes in vertical profiles of atmospheric temperature. The Livermore research attempts to understand how different mechanisms affect atmospheric temperatures, and hence tropopause height. It is the first study to show that a model-predicted "fingerprint" of tropopause height changes can be identified in observations. The paper describing this work, entitled, "Contributions of Anthropogenic and Natural Forcing to Recent Tropopause Height Changes," appears in the July 25 edition of Science. It involves a team of Livermore scientists (Benjamin Santer, Karl Taylor and James Boyle) and researchers from Lawrence Berkeley National Laboratory, the National Center for Atmospheric Research, the Institut für Physik der Atmosphäre in Germany and the University of Birmingham in the United Kingdom. Using a computer model of the climate system, the Lab scientists and their colleagues examined changes in both man-made forcings (well-mixed greenhouse gases, tropospheric and stratospheric ozone, and the scattering effects of sulfate aerosols) and natural external forcings (solar irradiance and volcanic aerosols). Experiments were performed with a model developed jointly by the National Center for Atmospheric Research and Los Alamos National Laboratory. The innovative aspect of these model runs is that climate forcings were varied both individually and in concert. This allowed the researchers to estimate the contribution of each forcing to overall changes in atmospheric temperature and tropopause height. Completion of this very large ensemble of model runs was made possible by recent developments in high performance computing capabilities at U.S. Department of Energy and National Science Foundation facilities. Output from these and other related climate model runs is available at The model results reveal the key drivers of recent tropopause height increases -- human-caused changes in well-mixed greenhouse gases and stratospheric ozone -- act primarily through warming of the troposphere (greenhouse gases) and cooling of the lower stratosphere (ozone). Both of these effects increase tropopause height. "Tropopause height is an integrated indicator of human-induced climate change," Santer said. "It reflects global-scale changes in the temperature structure of the atmosphere. Our research shows that the increase in tropopause height over the second half of the 20th century was predominantly due to human activity, and provides independent support for claims of recent tropospheric warming." Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

Ozone Holes

July 16, 2003

https://www.sciencedaily.com/releases/2003/07/030716091100.htm

Satellites See Lightning Strikes In Ozone's Origins

During summertime ozone near the Earth's surface forms in most major U.S. cities when sunlight and heat mix with car exhaust and other pollution, causing health officials to issue "ozone alerts." But in other parts of the world, such as the tropical Atlantic, this low level ozone appears to originate naturally in ways that have left scientists puzzled. Now, NASA-funded scientists using four satellites can tell where low level ozone pollution comes from and whether it was manmade or natural.

Atmospheric scientist David Edwards and his colleagues from the National Center for Atmospheric Research (NCAR) and collaborators in Canada and Europe have studied this problem using satellite data from three NASA spacecraft, one from the European Space Agency (ESA), and a computer model from NCAR. They were surprised to find that a greater amount of near-surface ozone over the tropical Atlantic develops as a result of lightning instead of agricultural and fossil fuel burning. Their findings appeared in a recent issue of the American Geophysical Union's Journal of Geophysical Research Atmospheres. The formation of ozone involves several factors, such as lightning and pollution from agricultural and fossil fuel burning, which is why it was helpful to use NASA's multiple satellites to look at each in turn. NASA satellites included Terra, the Tropical Rainfall Measuring Mission (TRMM), and Earth Probe/TOMS. ESA's ERS-2 satellite was also used to look at ozone, and NCAR's MOZART-2 (Model for OZone And Related chemical Tracers) computer model was used to simulate the chemical composition of the atmosphere. Because the different satellite instruments could detect fires, lightning flashes, and the resulting pollution and ozone in the atmosphere, respectively, they provided a bird's-eye global view of what was going on, and the computer model helped tie all the pieces together. Fires create smoke and carbon monoxide, and lightning creates nitrogen oxides (NOx). All of these come together with other unstable compounds in a chemical soup, and sunlight helps trigger the reaction that helps form ozone. The scientists found that in the early part of the year, the intense fires set by farmers for land-clearing and traditional cultivation in north-western Africa, just south of the Sahara Desert, resulted in large amounts of pollution that they could track using satellite images as it spread over the Atlantic towards South America. This pollution greatly increased ozone at low altitudes near the fires. However, when Edwards and his colleagues looked at areas of elevated ozone levels measured by satellites and aircraft over the Atlantic south of the equator, they were more surprised to find that this ozone was caused mainly by lightning rather than the fires. In other parts of the world, especially near cities, ozone near Earth's surface is often made from pollution as a result of industrial fossil-fuel burning and cars. Understanding where the pollution comes from in each case is important for improving our air quality. NASA's Measurements of Pollution in the Troposphere (MOPITT) instrument aboard the Terra satellite is a joint NASA/Canadian Space Agency mission that measured carbon monoxide concentrations at various levels of the atmosphere. The TOMS instrument on EP/TOMS measured tropical tropospheric ozone over the mid-Atlantic. The TRMM satellite counted the number of fires in a region using its Visible/Infrared Scanner (VIRS), and also catalogued lightning flash data from its Lightning Imaging Sensor (LIS). The satellite data was then interpreted using the MOZART-2 computer model. Previously, scientists used TOMS observations to get a general idea of where the tropospheric ozone levels were high, but it was often difficult to say where the ozone came from and which pollution source or natural process led to its creation. Only recently has the 4 satellite combination enabled scientists to make this distinction. This research was funded by NASA's Earth Science Enterprise (ESE), in cooperation with the National Science Foundation, sponsor of NCAR. NASA's ESE is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space.

Ozone Holes

July 10, 2003

https://www.sciencedaily.com/releases/2003/07/030710091534.htm

City-grown Air Pollution Is Tougher On Country Trees

ITHACA, N.Y. -- A tree grows in Brooklyn -- despite big-city air pollutants. Meanwhile, identical trees planted downwind of city pollution grow only half as well -- a surprising finding that ecologists in a Cornell University-based study, reported in the current issue of Nature (July 10, 2003), attribute to an atmospheric-chemistry "footprint" that favors city trees.

"I know this sounds counterintuitive but it's true. City-grown pollution -- and ozone in particular -- is tougher on country trees," says Jillian W. Gregg, lead author of the Nature cover article, "Urbanization effects on tree growth in the vicinity of New York City." Other authors of the Nature report are Clive G. Jones, an ecologist at the Institute of Ecosystem Studies in Millbrook, N.Y., where some of the field studies were conducted, and Todd E. Dawson, professor of integrative biology at the University of California, Berkeley, and a professor at Cornell when the study began. Gregg was a Cornell graduate student, pursuing a Ph.D. in ecology, when she started planting identical clones of cottonwood trees (also known as poplars, or by the scientific name Populus deltoides ) in and around New York City. Test sites included the New York Botanical Garden and the Hunts Point water works in the Bronx; a Consolidated Edison fuel depot in Astoria, Queens; as well as Long Island's Brookhaven National Laboratory in Upton; Eisenhower Park in Hempstead; and the Cornell Horticultural Research Laboratory in Riverhead. About 50 miles north of Manhattan, in the Hudson River valley, she also planted cottonwood clones at the Millbrook institute. One aim of the study was to show the impact on plants of a tough life in the city, where a variety of gaseous, particulate and photochemical pollutants from fossil-fuel combustion bombard plants as they struggle to grow in heavy metal-laden soils. The fast-growing poplars were to serve as a kind of "phytometer" to gauge the net effect of urban and industrial pollutants on urban and rural ecosystems. For three consecutive growing seasons Gregg returned to the sites to plant cottonwoods, harvesting them to weigh their biomass and to perform other kinds of analyses. She controlled for differences in light, precipitation, season length and soil factors, making air quality the primary factor of concern. The experimental cottonwoods growing in Queens and the Bronx "breathed" the same pollutants as did other plants (and people) in the boroughs. So did cottonwoods along the Hudson and on Long Island. Unexpectedly, the city trees thrived. As reported in Nature , "…urban plant biomass was double that of rural sites." The ecologist knew that some fallout from pollutants and warmer microclimates in "heat islands" can actually enhance plant growth. However nutrient budgets, chamber experiments and regression analyses by the researchers showed these factors could not account for the increased urban tree growth. Rather, the difference is ozone, the researchers now believe. Desirable as three-atom oxygen is in the stratosphere (where the ozone layer helps shield earthly life from the sun's ultraviolet radiation), excess ozone at ground level interferes with plants' metabolism. One sign of severe exposure to ozone is necrosis, or cell death, with brown spots marring plant leaves. But in some areas of metropolitan New York City, as well as in other polluted cities, Gregg and her colleagues have found "footprints" of lower-than-expected ozone exposures. As Gregg explains the facts of atmospheric chemistry in the city, "Ozone is what we call a secondary pollutant. So while the primary precursors for ozone are emitted in the city, they must act in the presence of sunlight, over time, before ozone is formed. By then, the air mass has moved to rural environments." The Big Apple air situation is even more complicated, Gregg notes, because the city is downwind from New Jersey, another densely populated and industrialized region. "A lot of the ozone moving into New York City was grown in the so-called Garden State," the ecologist says. However, the reactions of ozone formation are cyclical, with the presence of one of the primary precursors, nitric oxide (NO) -- which occurs in high concentrations in the urban atmosphere -- destroying ozone once it has formed. As new NO compounds develop, three-atom oxygen is reduced to the more benign, two-atom kind. Ironically, NO concentrations are very low in most rural areas, so ozone remains in the atmosphere there and plants' exposure period to the harmful gas is extended. (Although one-hour peak ozone exposures can be high in urban centers, exposure periods last longer in rural environments, resulting in higher cumulative exposures.) Trees and other plants growing within the lower cumulative ozone exposures of the urban-ozone footprints benefit from the NO scavenging reactions that reduce the ozone-exposure period. Trees growing in the purportedly clean rural areas aren't so lucky. The study was supported, in part, by the U.S. Environmental Protection Agency, the Edna Bailey Sussman Fund for Environmental Internships, the New York State Heritage Foundation, the Mellon Foundation , Cornell's Department of Ecology and Systematics, the Institute of Ecosystem Studies, the Cornell Center for the Environment and Sigma Xi.

Ozone Holes

June 3, 2003

https://www.sciencedaily.com/releases/2003/06/030603083134.htm

Chicago Lake Breeze Effect Could Increase Asthma Risk

CHICAGO, June 1 — Chicago has long been known as one of the nation's worst cities for asthma sufferers. Now scientists think they may know why. The culprit, they say, is the familiar lake breeze effect that moves commuter-generated air pollution back and forth between the city and Lake Michigan.

Researchers have long known about this daily atmospheric swapping of air masses, but only now have they been able to identify and measure the concentrations of individual pollutants at different times during the cycle. In doing so, they have confirmed that the initial pollutants react with each other in a kind of chemical reactor over Lake Michigan, generating more toxic compounds. As the air mass moves back toward the city, residents may be exposed to high concentrations of these hazardous substances before they have a chance to dissipate. The research was presented at a Great Lakes Regional Meeting of the American Chemical Society, the world's largest scientific society, by Martina Schmeling, Ph.D., assistant professor of chemistry at Loyola University Chicago, and Paul Doskey, Ph.D., of Argonne National Laboratory's Environmental Research Division. The researchers looked specifically at particulate and ozone air pollution. "Particulate air pollution contributes to many urban problems including low visibility, fog and cloud formation," Schmeling said. Particulates and ozone are also considered the most likely triggers of respiratory diseases like asthma. The group measured several different pollutants including ozone, sulfate, nickel and lead. Measurements were taken from LUCAS, the Loyola University Chicago Air Monitoring Station. "High-powered instrumentation made it possible for the first time to identify pollutants before and during the lake breeze in Chicago and compare the differences," Schmeling explained. The differences were surprising. The lake breeze effect interacts with particulate air pollution rising over Chicago from approximately 5-7 million commuters during the early morning rush hour. It then gets swept over the lake by offshore winds. "Above the lake [the pollutants] react with each other, initiated by the intense sun light... like in a giant reactor," Schmeling said. When the breezes blow this processed pollution back over the city and suburbs at night it is more reactive. "More reactive particulates could be more health impacting," Schmeling said, suggesting that these findings could have a "broad impact on the community." Doskey agreed: "City residents may experience an acute, short-term exposure to high concentrations of pollutants as the leading edge of the lake breeze returns to land." Already Chicago and its suburbs lead the nation in number of asthma cases per capita per year. Since the lake breeze effect is most pronounced during the early summer months, Schmeling, Doskey and their colleagues plan further testing in June. The researchers also plan to study data from Detroit, Toronto and other cities with similar meteorological patterns.

Ozone Holes

March 31, 2003

https://www.sciencedaily.com/releases/2003/03/030331045035.htm

NASA Finds Wide Annual Fluctuations In Arctic Ozone Loss

Ozone depletion over Earth's Arctic region varies widely from year to year in its amount, timing and pattern of loss. That's the conclusion of a research team using data from the Microwave Limb Sounder on NASA's Upper Atmosphere Research Satellite.

The findings, published in the current issue of the Journal of Geophysical Research, provide the first consistent, three-dimensional picture of ozone loss during multiple Arctic winters. The findings confirm previous Arctic ozone loss estimate variations. "This work provides a consistent picture of how Arctic ozone loss varies between winters," said lead researcher Dr. Gloria Manney, a senior research scientist with NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Scientists will have a better understanding of current Arctic ozone conditions and be better able to predict variations in the future." Manney said NASA's unique vantage point in space provides data needed by policy makers. "They need accurate data to show whether current regulations on ozone-depleting substances are having the desired effect," she said. "In this way, NASA is providing a vital piece of the puzzle needed to understand this global phenomenon." Ozone is a form of oxygen that shields life on Earth from harmful ultraviolet radiation. Earth's stratospheric ozone layer is thinning around the world outside of the tropics. This thinning is a result of chlorofluorocarbons produced by industrial processes, which form reactive compounds like chlorine monoxide in the stratosphere during winter. To date, ozone loss has been most pronounced over Antarctica, where colder conditions encourage greater ozone loss and result in an ozone hole. Higher temperatures and other differences in atmospheric conditions in the Arctic have thus far prevented similarly large depletions. Nevertheless, as Manney and her colleagues validated in 1994, widespread Arctic ozone loss also occurs, and scientists are eager to understand it better, since formation of Arctic ozone hole could negatively affect populations in Earth's far northern latitudes. Many uncertainties remain regarding ozone depletion. Scientists want to know what is causing ozone decreases in Earth's mid latitudes. They also wish to assess effects of climate change on future ozone loss, especially in the northern hemisphere high latitudes. In the new study, Manney's team reanalyzed Microwave Limb Sounder observations during seven Arctic winters (1991 - 2000) to estimate chemical ozone loss. To yield accurate estimates, the team developed a model to account for naturally occurring ozone variations resulting from atmospheric transport processes such as wind variability. Their results show large year-to-year variability in the amount, timing and patterns of Arctic ozone loss. Ozone depletion was observed in the Arctic vortex each year except 1998, when temperatures were too high for chemical ozone destruction. This vortex is a band of strong winds encircling the North Pole in winter like a giant whirlpool. Inside the vortex, temperatures are low and ozone-destroying chemicals are confined. Ozone loss was most rapid near the vortex edge, with the biggest losses in 1993 and 1996. The greatest losses occurred in the months of February and March. The variability in the size, location and duration of the Arctic vortex is driven by meteorological conditions. High mountains and land-sea boundaries in the northern hemisphere interact with wind variations to generate vast atmospheric undulations that displace air as they travel around Earth. These waves form in the troposphere (the lowest atmospheric layer), where they produce our winter storms, and propagate upward, depositing their energy in the stratosphere. The energy from these waves warms the stratosphere, suppressing formation of polar stratospheric clouds necessary for ozone destruction. Arctic ozone loss tends to be greatest in years when these wave motions are unusually weak. NASA's Microwave Limb Sounder experiments measure naturally occurring microwave thermal emissions from the limb of Earth's atmosphere to remotely sense vertical profiles of selected atmospheric gases, temperature and pressure. These data are unique in their ability to show the three-dimensional evolution of ozone loss over time. The Microwave Limb Sounder on the Upper Atmosphere Research Satellite was the first such experiment in space. A next-generation Microwave Limb Sounder, developed and built at JPL for the Aura mission of NASA's Earth Observing System, is scheduled for launch in 2004. That instrument will provide simultaneous observations of ozone and one or more long-lived trace gases, substantially advancing future studies of ozone loss. The California Institute of Technology in Pasadena manages JPL for NASA. For more information about the Microwave Limb Sounder, see:

Ozone Holes

March 24, 2003

https://www.sciencedaily.com/releases/2003/03/030324064332.htm

New NCAR Analysis Sheds Light On The Northern Hemisphere's Springtime Ozone Peak

BOULDER -- Scientists at the National Center for Atmospheric Research (NCAR) and colleagues at universities and NASA have clarified the process by which ozone--an essential shield in the stratosphere, but a pollutant at lower levels--reaches its peak abundance across North America each spring. The new findings come from a comprehensive study that links computer models with airborne measurements of gases, particles, and ultraviolet radiation.

A set of papers outlining results from the Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiment appears in the February 28 issue of the Journal of Geophysical Research-Atmospheres (JGR). The principal investigators are NCAR scientists Elliot Atlas, Christopher Cantrell, and Brian Ridley. In addition to its important role in chemical reactions that determine the "cleansing capacity" of the atmosphere, tropospheric ozone "is known to have detrimental effects on human health and agricultural crop production," note the authors. Recent evidence also points to a significant relationship between tropospheric ozone chemistry and toxic trace elements, such as mercury. In the lower to middle troposphere, about one to five miles above the United States and Canada, ozone levels peak as springtime arrives. "Understanding the sources of this ozone and the processes that produce and destroy it will help us determine how human-produced emissions affect air quality on a global scale," says Atlas. It's been unclear whether the ozone peak develops due to seasonal intrusions of ozone-rich air from the stratosphere above or whether it forms in place through photochemical effects of the intensifying spring sun. The answer, the TOPSE team found, is a little of both, though photochemical effects dominate in the winter-to-spring ozone increase. From February to May 2000, scientists from NCAR and other institutions took to the skies above North America for the TOPSE field campaign. Seven round-trip flights aboard the National Science Foundation/NCAR C-130 aircraft took scientists and instruments from Broomfield, Colorado, to northernmost Canada (up to latitude 87 degree N) and back. The team then analyzed the results and compared them to the output of two computer models that simulate air chemistry and winds over the Northern Hemisphere. Together, the data and model results paint a picture that answers some key questions about springtime ozone and air chemistry above North America. For example, the flight data strongly confirmed that the amount of ozone descending from the stratosphere was too small to account for the springtime peak. By tracing chemical reactions and following stratospheric "markers" through their models, the scientists found that "stratospheric sources could only account for a small fraction of the observed ozone [during the spring increase], but stratospheric ozone is an important contributor to the observed background levels." Thus, "the seasonal ozone trend was primarily driven by in situ [in-place] ozone production." By late spring, up to five times more ozone was found to be produced locally than delivered from aloft. TOPSE also addressed a quite different puzzle: how ozone can disappear so quickly in wintertime from surface air across the Arctic Ocean and adjacent land areas. As reported in previous studies, Arctic surface ozone depletion appears to be due to natural halogen compounds, such as bromine and chlorine, that react with ozone and the Arctic snowpack as the spring sun arrives. This surface ozone depletion in the north is unrelated to the better-known ozone "hole" in the Antarctic stratosphere, which also forms in the spring. That southern ozone thinning involves a different set of reactions with chlorine derived from industrial chemicals, including chlorofluorocarbons. During TOPSE, "A virtual ozone hole was observed for the first time over much of Hudson Bay and over the Arctic Ocean," write the authors. Low-level winds, they note, "can distribute ozone-depleted air over a larger region beyond the Arctic than had been previously recognized." TOPSE was able to map episodes of surface ozone depletion over much of the Arctic Ocean, northern Canada, and Greenland. The Arctic Ocean appears to be the origin of these depletions, but winds can move these chemically processed air masses to more southerly latitudes. Even at its peak levels, Northern Hemisphere ozone is far less prevalent in the lower to middle troposphere than in the higher stratosphere. This means that the seasonal waxing and waning at lower altitudes studied in TOPSE should have little effect on the ultraviolet light that reaches people, animals, and plants. Still needed, according to TOPSE scientists, are more-extensive measurements of the halogens that drive ground-level Arctic ozone depletion, as well as a better understanding of the atmospheric exchange between stratosphere and troposphere--a process the scientists note is "far from understood." ###The National Science Foundation provided major funding for TOPSE. On the Web:

Ozone Holes

March 20, 2003

https://www.sciencedaily.com/releases/2003/03/030320073502.htm

Surprise! Lightning Has Big Effect On Atmospheric Chemistry

Scientists were surprised to learn summer lightning over the U.S. significantly increases regional ozone and other gases that affect air chemistry 3 to 8 miles above Earth's surface. The amounts of ozone and nitrogen oxides created by lightning surpass those generated by human activities in that level of the atmosphere.

Typically over the U.S., fossil fuel burning is the main cause of nitrogen oxides (NOx), which lead to the formation of ozone near the Earth's surface. However, above the Earth's surface in the free troposphere (3-8 miles high), during the summer months, lightning activity increases NOx by as much as 90 percent and ozone by more than 30 percent.Renyi Zhang of Texas A&M University, lead author of a paper that recently appeared in the Proceedings of the National Academy of Sciences, suggests lightning has distinct impacts on air chemistry over the U.S. Human activities dominate the creation of these gases near the Earth's surface, but lightning plays a bigger role in the free troposphere. Depending on where ozone resides, it can protect or harm life on Earth. Most ozone resides in the stratosphere (a layer of atmosphere between 8 and 25 miles high), where it shields life on Earth from the sun's harmful ultraviolet radiation. At the surface, ozone is a harmful pollutant that causes damage to lung tissue and plants. In the tropopause (surface to 8 miles high) ozone also is a radiatively active gas that affects climate.About 77 million lightning bolts annually strike the U.S. Measurements before and after lightning strikes have confirmed the generation of nitrogen oxides in the atmosphere. "Ironically, over the United States lightning accounts for only about 5 percent of the total U.S. nitrogen oxide annual emissions and about 14 percent of the total emissions in July," said Zhang. Although the largest source of NOx over the U.S. is fossil fuel burning, lightning still plays a dominant role in influencing the regional air chemistry. The explanation is NOx from fossil fuel burning is released close to the Earth's surface and is consumed rapidly by chemical reactions before being transported upward. Lightning, however, directly releases NOx throughout the entire troposphere. The lightening source over North America for NOx is sufficiently large, so that it has implications on free troposphere NOx over other parts of the world, most notably Europe, which is downwind of the U.S., given the prevailing westerly flow in the Northern Hemisphere mid-latitudes.NASA funded this research, because one mission of NASA's Earth Science Enterprise is to assess and understand the primary causes of changes in Earth's system, including man-made and natural causes.The objective of Zhang's work is to assess the impact of how the U.S. human-induced (mainly fossil fuel burning) and natural (lightning) sources contribute to air pollution in the lower and upper troposphere. He collaborated with Dr. Xuexi Tie of the National Center for Atmospheric Research (NCAR).Zhang used lightning measurements from the ground-based National Lightning Detection Network and the Optical Transient Detector (OTD) instrument to obtain the number of lightning flashes over the U.S. The OTD, aboard the Microlab satellite, is the world's first space-based sensor capable of detecting and locating lightning events during day and night, with high detection efficiency.This research was partially supported by NASA's New Investigator Program in Earth Science and the Texas Air Research Center. The National Science Foundation supports NCAR.

Ozone Holes

March 13, 2003

https://www.sciencedaily.com/releases/2003/03/030313081900.htm

Mt. Pinatubo Eruption Provides A Natural Test For The Influence Of Arctic Circulation On Climate

A recent NASA-funded study has linked the 1991 eruption of the Mount Pinatubo to a strengthening of a climate pattern called the Arctic Oscillation. For two years following the volcanic eruption, the Arctic Oscillation caused winter warming over land areas in the high and middle latitudes of the Northern Hemisphere, despite a cooling effect from volcanic particles that blocked sunlight.

One mission of NASA's Earth Science Enterprise, which funded this research, is to better understand how the Earth system responds to human and naturally-induced changes, such as large volcanic eruptions. "This study clarifies the effect of strong volcanic eruptions on climate, important by itself, and helps to better predict possible weather and short-term climate variations after strong volcanic eruptions," said Georgiy Stenchikov, a researcher at Rutgers University's Department of Environmental Sciences, New Brunswick, N.J., and lead author on a paper that appeared in a recent issue of the Journal of Geophysical Research. A positive phase of the Arctic Oscillation has slowly strengthened over the few last decades and has been associated in prior research with observed climate warming. "The study has important implications to climate change because it provides a test for mechanisms of the Arctic Oscillation," Stenchikov said. A positive phase of the Arctic Oscillation is associated with strengthening of winds circulating counterclockwise around the North Pole north of 55°N, that is, roughly in line with Moscow, Belfast, and Ketchikan, Alaska. In winter these winds pull more warm air from oceans to continents causing winter warming, and like a top spinning very fast, they hold a tight pattern over the North Pole and keep frigid air from moving south. According to this research, temperature changes caused by a radiative effect of volcanic aerosols in two lower layers of the atmosphere, the troposphere and the stratosphere, can lead to a positive Arctic Oscillation phase. The troposphere extends from Earth's surface to an altitude of 7 miles in the polar regions and expands to 13 miles in the tropics. The stratosphere is the next layer up with the top at an altitude of about 30 miles. The study uses a general circulation model developed at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory to simulate how volcanic aerosols following the Pinatubo eruption impacted the climate. In the troposphere, volcanic aerosols reflect solar radiation and cool the Earth's surface, decreasing temperature differences between the equator and the North Pole in the bottom atmospheric layer. These changes end up inhibiting processes that slow counterclockwise winds that blow around the North Pole mostly in the stratosphere. This in turn strengthens a positive phase of the Arctic Oscillation. In the stratosphere, volcanic aerosols absorb solar radiation, warm the lower stratosphere (about 15 miles above the Earth's surface) and increase stratospheric temperature differences between the equator and the North Pole. These changes strengthen westerly winds in the lower stratosphere and help to create a positive phase of the Arctic Oscillation. In previous research, an observed positive Arctic Oscillation trend has been attributed to greenhouse warming that led to an increase of stratospheric temperature differences between equator and pole. But this study finds that tropospheric temperature change in the course of climate warming may play an even greater role. In one type of computer simulation, Stenchikov and colleagues isolated the contribution of a decreased temperature difference in the troposphere, and found that it could produce a positive phase of the Arctic Oscillation by itself. That's because greenhouse heating near the North Pole melts reflective sea ice and snow, and reveals more water and land surfaces. These surfaces absorb the Sun's rays and increasingly warm the Earth's polar regions. Polar heating at the Earth's surface lessens the temperature differences between the equator and North Pole in the troposphere, which ultimately strengthens a positive phase of the Arctic Oscillation. The study also finds that when aerosols get into the stratosphere, very rapid reactions that destroy ozone (especially in high latitudes) take place on the surfaces of aerosol particles. When ozone gets depleted, less UV radiation is absorbed in the stratosphere. This cools the polar stratosphere, and increases the stratospheric equator-to-pole temperature difference, creating a positive phase of the Arctic Oscillation. Ozone data were obtained from NASA's Total Ozone Mapping Spectrometer (TOMS) satellite and ozonesonde observations.

Ozone Holes

February 11, 2003

https://www.sciencedaily.com/releases/2003/02/030211072220.htm

Ozone Levels In Southern California Smog May Be Higher Than Current Air Quality Models Predict

Irvine, Calif., Feb. 10, 2003 -- Current air-quality models used for predicting air pollution may be underestimating ozone levels in Southern California by as much as 10% of the national one-hour ozone standard, a UC Irvine study has found.

Donald Dabdub, UCI professor of mechanical and aerospace engineering, and post-doctoral researcher Eladio Knipping reached this conclusion after making adjustments to a computer model that calculates pollution levels in the South Coast Air Basin of California. In adjusting the model, the researchers added the impact of sea-salt particles in the coastal air. These salts release small amounts of chlorine, which mixes with smog and morning sunlight to create small amounts of ozone. Currently, sea salt-derived chlorine information is not included in any official regulatory models. Dabdub and Knipping determined that predicted ozone levels could increase by as much as 12 parts-per-billion (ppb) in coastal regions and afternoon peak levels by 4 ppb. In comparison, Southern California daily peak ozone levels in 2001 exceeded the one-hour national standard of 120 ppb on 36 days and the one-hour California standard of 90 ppb on 121 days. Study results appear in the Jan. 15, 2003 issue of Environmental Science & Technology. "The chemistry of sea-salt particles appears to be important for correctly predicting air pollutant concentrations in coastal urban regions," said Dabdub, who studies the mathematical modeling of air pollution. "Inclusion of sea-salt chlorine chemistry should be considered in order to improve regulatory models in coastal regions."An earlier UCI study first determined that sunlight, pollutants and the ocean spray combine to enhance the urban production of ozone. The study found that sea-salt particles in coastal air undergo a chemical reaction on their surface, which in turn releases chlorine molecules. Sunlight then breaks down these molecules into individual, highly reactive chlorine atoms. When these atoms enter the chemical stew of early-morning smog, they react with fossil-fuel pollutants and contribute to the formation of ozone.Ozone is a pollutant that is commonly created when combustion emissions and other sources react to sunlight. It is known to irritate the tissues of the eyes, nose and lungs, causing inflammation and breathing difficulties.The National Science Foundation and California Air Resources Board supported the work.

Ozone Holes

January 31, 2003

https://www.sciencedaily.com/releases/2003/01/030131075758.htm

Ozone May Provide Environmentally Safe Protection For Grains

WEST LAFAYETTE, Ind. - Taking a clue from air purification systems used in surgical suites, Purdue University researchers have discovered that ozone can eliminate insects in grain storage facilities without harming food quality or the environment.

Ironically, the gas is being touted as a fumigant alternative in response to an international treaty banning the use of ozone-layer harming chemicals currently used to rid food storage facilities of insects. When ozone is used for killing grain insects, it lasts for a very short period of time without damaging the environment or the grain, the Purdue scientists report in the January issue Journal of Stored Products Research. "Ozone has a very short half-life and we're using relatively low dosages, but enough to kill an insect," said Linda Mason, Purdue entomology associate professor and co-author of the study. "The chemicals currently used can kill everything in and around the grain bin, including people. With ozone, we're not generating ozone at deadly concentrations, and we have better control over it when it's present." Purdue's Post Harvest Grain Quality Research team began its studies in response to the 1987 Montreal Protocol, an international agreement to prohibit substances deemed dangerous to the Earth's ozone layer. One such substance is methyl bromide, commonly used against crop pests in the soil and in grain storage facilities. Beginning in 2005, it no longer will be available. A replacement for chemical fumigants is imperative because insects not only eat the grain, they defecate on it causing development of fungi, primarily Fusarium and Aspergillus. These fungi can release potentially deadly mycotoxins that can cause illness in most livestock and have been linked to some forms of human cancer. In humans, approximately 76 million cases of food-borne disease occur annually in the United States, according to the Centers for Disease Control and Prevention. Experts estimate that 5 percent to 10 percent of the world's food production is lost each year because of insects, and in some countries that figure is believed to be as high as 50 percent. In the latest study, Purdue researchers used ozone to treat rice, popcorn, soft red winter wheat, hard red winter wheat, soybeans and corn. They used five-gallon plastic pails and 50-gallon steel drums, storage bins filled with grain, and buried mesh bags all filled with grain and a known number of grain-eating bugs to test ozone's killing efficacy. The team's previous studies on ozone flow and effectiveness in eliminating insects were done either in similar storage containers or in 500-bushel bins built for pilot studies at the Purdue Agronomy Farm. The ozone treatment of grain included two applications of ozone. In the first, the ozone moves through the grain slowly because the gas reacts, or bonds, with matter on the grain surface. This first treatment allows ozone to react with most of the grain surface and degrades the ozone, Mason said. With the second ozone application, the gas moves through the grain more quickly because it isn't slowed by reactions with the grain. This allows the ozone to kill the insects by reacting with them rather than the grain. Testing different grains allowed the scientists to answer two important questions. One was whether ozone flowed differently through grains that were less porous or of a different kernel size than corn, such as wheat. The second was how exposure to ozone affects the quality of food products made from the treated grain. Dirk Maier, a Purdue agricultural and biological engineering professor, studied how to make the ozone flow efficiently and effectively through grain storage bins. Charles Woloshuk, a botany and plant pathology professor, studied ozone effects on molds and mycotoxins. Fidel Mendez, a botany master's degree student, studied the final products produced from the treated grain to determine if they were the same quality as those made from untreated grain. "We wanted to determine if the grain looked any different; if it milled the same way; if it made flour the same way. Does bread taste the same when made from ozonated wheat?" Mason said. "Essentially, there were no differences. The food industry can take grain that's been treated with ozone and know it won't affect their ability to come up with the same products in the end." The team also checked how ozone treatments affected amounts of important amino acids and essential fatty acids, fats not produced by the body. The treatments caused no significant difference in any of the nutritional and metabolic values of these substances in any of the grains studied, Mason said. The scientists began their study after a company that uses ozone air purification systems in hospitals noticed that air vents were cockroach free. Absence of cockroaches in a large building is unusual, so the researchers tested various ozone doses on different insects and found the gas was fatal to bugs. "All the species we tested seemed affected," Mason said. "The only ones we don't have control over are immature weevils since they are hidden within the kernels. Ozone, unlike chemical fumigants, doesn't penetrate into the kernel enough to kill immature insects." Currently, the researchers are studying ways to use ozone as a preventative treatment by possibly sealing of grain storage facilities with layers of ozone, much the way a jelly jar is capped with wax. The USDA National Research Initiative provided funding for this study.

Ozone Holes

January 24, 2003

https://www.sciencedaily.com/releases/2003/01/030124074808.htm

NASA Spacecraft Set To Catch Some Rays

A new NASA satellite is ready to leave the sandy coast of Florida and head to space to catch some rays. The SORCE (Solar Radiation and Climate Experiment) mission will study our sun's influence on our planet's climate by measuring how the star affects the Earth's ozone layer, atmospheric circulation, clouds, and oceans. The research data that will help us to better protect and understand our home planet.

SORCE is scheduled to launch from off the coast of the Kennedy Space Center, Fla., on January 25 aboard a Pegasus XL launch vehicle at approximately 3:14 p.m. EST. The Pegasus XL rocket is dropped from the wing of an L-1011 aircraft over the Atlantic Ocean. After falling a few seconds, the spacecraft's engines will power on and lift it into orbit. The satellite will orbit at an altitude of 397.8 miles (640 kilometers)."This mission will help to distinguish between natural and human-induced influences in climate change. Incoming light energy from the sun is ultimately what powers our climate system. Past NASA missions showed the amount of solar radiation is not constant, but rather varies over time. SORCE will help us understand these variations, and the role of solar variability in climate change," said Dr. Ghassem Asrar, NASA's Associate Administrator for Earth Science.SORCE is a small free-flying satellite carrying four scientific instruments to measure the solar radiation at the top of the Earth's atmosphere and how the sun influences Earth's atmosphere and climate. The four instruments on SORCE are the Total Irradiance Monitor, the Spectral Irradiance Monitor, Solar Stellar Irradiance Comparison Experiment, and the Extreme Ultraviolet Photometer System. The first three will measure solar irradiance and the solar spectrum to helpscientists understand the sun's role in climate change. The Photometer System will measure high-energy radiation from the sun."We are very excited as we near our launch date." said Bill Ochs, SORCE Project Manager at NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Md. "This mission has been atremendous team effort between the University of Colorado, NASA, and Orbital Sciences Corporation," he said.This mission is a joint partnership between NASA and the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP) in Boulder. SORCE is a principal investigator-led mission with GSFC providing management, scientific oversight and engineering support.Scientists and engineers at LASP designed, built, calibrated and tested the four science instruments on SORCE. LASP subcontracted with Orbital Sciences Corporation for thespacecraft and observatory integration and testing. The Mission Operations Center and the Science Operations Center are both operated at LASP. LASP will operate the spacecraftover its five-year mission life and is responsible for the acquisition, management, processing, and distribution of the science data.SORCE data will support studies in long-term climate change, natural variability, enhanced climate prediction, and atmospheric ozone and UV-B radiation. The SORCE measurementsare critical to studies of the variability of the sun; its effect on our Earth system; and its influence on humankind.SORCE is a part of NASA's Earth Science Enterprise, a program dedicated to understanding the Earth as an integrated system and applying Earth system science to improve prediction ofclimate, weather, and natural hazards using the vantage point of space.For more information about SORCE see:

Ozone Holes

January 23, 2003

https://www.sciencedaily.com/releases/2003/01/030123073016.htm

Rocket To Measure Auroral Waves

University of Alaska Fairbanks Poker Flat Research Range will open its 2003 launch season today with a single-rocket mission designed to measure high-frequency wave signals in connection with the aurora. Known as HIBAR, the high bandwidth auroral rocket mission will have until Feb. 8 to get the right weather and auroral conditions to launch a two-stage Terrier-Black Brant IX sounding rocket into the aurora at altitudes where the high-frequency waves form.

The mission comes as a result of analysis on data gathered from Poker Flat rocket launches in 1997 and 2002. Data from those missions revealed detailed structure of high-frequency waves that had never before been recorded, an exciting development in auroral physics. Analysis of the findings led to a theory about the waves' characteristics that will be tested by HIBAR. Historically, high-frequency waves in the ionosphere have been difficult to study because they occur at frequencies greater than 1 MHz, and spacecraft data telemetry rates have been inadequate to sample such waves. Recently, enhanced telemetry rates have become available on NASA sounding rockets at Poker Flat, allowing waves up to 5 MHz to be thoroughly measured. The principal investigator for the HIBAR mission is Dr. James LaBelle from the Department of Physics and Astronomy at Dartmouth College in Hanover, New Hampshire. Since it was founded 35 years ago, more than 1500 meteorological rockets and 250 major high-altitude sounding rocket experiments have been launched from Poker Flat Research Range to conduct atmospheric research on diverse subjects including the aurora, the ozone layer, solar protons and electric, magnetic and ultraviolet fields.

Ozone Holes

January 22, 2003

https://www.sciencedaily.com/releases/2003/01/030122072843.htm

Earth Likely Spared From One Form Of Cosmic Doom

We have one less thing to worry about. While the cosmic debris from a nearby massive star explosion, called a supernova, could destroy the Earth's protective ozone layer and cause mass extinction, such an explosion would have to be much closer than previously thought, new calculations show.

Scientists at NASA and Kansas University have determined that the supernova would need to be within 26 light years from Earth to significantly damage the ozone layer and allow cancer-causing ultraviolet radiation to saturate the Earth's surface. An encounter with a supernova that close only happens at a rate of about once in 670 million years, according to Dr. Neil Gehrels of NASA's Goddard Space Flight Center in Greenbelt, Md., who presents these findings today at the American Astronomical Society meeting in Seattle. "Perhaps a nearby supernova has bombarded Earth once during the history of multicellular life with its punishing gamma rays and cosmic rays," said Gehrels. "The possibility for mass extinction is indeed real, yet the risk seems much lower than we have thought." The new calculations are based largely on advances in atmospheric modeling, analysis of gamma rays produced by a supernova in 1987 called SN1987a, and a better understanding of galactic supernova locations and rates. A supernova is an explosion of a star at least twice as massive as our Sun. Previous estimates from the 1970s stated that supernovae as far as 55 light years from Earth could wipe out up to 90 percent of the atmosphere for hundreds of years. The damage would be from gamma rays and cosmic rays, both prodigiously emitted by supernovae. Gamma rays are the most energetic form of light. Cosmic rays are atomic particles, the fastest-moving matter in the Universe, produced when the expanding shell of gas from the exploded star runs into surrounding dust and gas in the region. Gamma rays, moving at light speed, would hit the Earth's atmosphere first, followed closely by the cosmic rays moving at close to light speed. Gamma-ray light particles (called photons) and the cosmic-ray particles can wreak havoc in the upper atmosphere, according to Dr. Charles Jackman of NASA Goddard, who provided the atmospheric analysis needed for the new calculation. The particles collide with nitrogen gas (N2) and break the molecule into highly-reactive nitrogen atoms (N). The nitrogen atoms then react fairly quickly with oxygen gas (O2) to form nitric oxide (NO) and, subsequently, other nitrogen oxides (NOx). The nitrogen oxide molecules can then destroy ozone (O3) through a catalytic process. This means that a single NOx molecule can destroy an ozone molecule and remain intact to destroy hundreds of more ozone molecules. The new calculations -- based on the NASA Goddard two-dimensional photochemical transport model -- show that a supernova within 26 light years from Earth could wipe out 47 percent of the ozone layer, allowing approximately twice the amount of cancer-causing ultraviolet radiation to reach the Earth's surface. Excessive UV radiation is harmful to both plants and animals, thus a doubling of UV levels would be a significant problem to life on Earth. The gamma-ray irradiation would last 300 to 500 days. The ozone layer would then repair itself, but only to endure cosmic-ray bombardment shortly after, lasting at least 10 years. (Cosmic rays are electrically charged particles whose paths are influenced by magnetic fields, and the extent of such fields in the interstellar medium is not well understood.) The calculations simultaneously point to the resilience of the ozone layer as well as its fragility in a violent Universe, said Dr. Claude Laird of the University of Kansas, who developed the gamma-ray and cosmic ray input code and performed the atmospheric model simulations. Although the ozone layer should recover relatively rapidly once the particle influx tapers off -- within about one to two years, the Goddard models show -- even this short period of time is sufficient to cause significant and lasting damage to the biosphere. "The atmosphere usually protects us from gamma rays, cosmic rays, and ultraviolet radiation, but there's only so much hammering it can take before Earth's biological defenses break down," he said. Dr. John Cannizzo of NASA Goddard and University of Maryland, Baltimore Country, initiated and coordinated the new calculations. "I've long been fascinated by the possibility of extinction from something as remote as a star explosion," he said. "With this updated calculation, we essentially worked backwards to determine what level of ozone damage would be needed to double the level of ultraviolet radiation reaching the Earth's surface and then determined how close a supernova would need to be to cause that kind of damage." These results will appear in the Astrophysical Journal 2003, March 10, vol. 585. Co-authors include Barbara Mattson of NASA Goddard (via L3 Com Analytics Corporation) and Wan Chen of Sprint IP Design in Reston, Virginia.

Ozone Holes

January 7, 2003

https://www.sciencedaily.com/releases/2003/01/030107072313.htm

Two Global Pollutants Work To Offset Each Other, According To Colorado Study

University of Colorado at Boulder researchers have found, ironically, that two pollutants -- carbon dioxide and hydrocarbons emitted from agricultural forest trees -- offset each other somewhat in mitigating air quality problems.

Carbon dioxide, believed by scientists to be a major factor in greenhouse warming, has been shown to reduce "agriforest" emissions of hydrocarbons that contribute to ground-based ozone pollution, according to CU-Boulder doctoral candidate Todd Rosenstiel of the environmental, population and organismic, or EPO, biology department. Commercial agriforests made up of trees including poplars, Eucalyptus and Acacia emit high levels of isoprene, a highly reactive chemical species believed to contribute heavily to ground-based ozone, said Rosenstiel, co-chief author of the study. While this may seem like a good thing environmentally to some people, Rosenstiel is more cautious. "The effects of CO2 are unpredictable. The bigger picture is the rapidly growing amount of these agriforests worldwide emitting hydrocarbons like isoprene in much larger volumes. "We still do not know enough about the basic chemistry and biochemistry of isoprene to predict what may happen in the future," Rosenstiel said. "One thing we have shown is that 'tweaking' environmental conditions where such trees grow through changes in water consumption, temperature and soil conditions may have significant effects on isoprene emissions." As people replace natural forests with agriforests, the species do produce significant amounts of hydrocarbons like isoprene," said Russell Monson, chair of CU-Boulder's EPO biology department. "The news here is that we have found a situation where elevated CO2 concentrations work in a positive way to reduce pollution from isoprene, that combines with sunlight and vehicle and industrial pollution to form smog and related lung problems in people." A paper on the subject was published electronically today by Nature magazine. The primary authors are Rosenstiel and Mark Potosnak of Columbia University, now with the National Center for Atmospheric Research in Boulder. Other authors include Kevin Griffin of Columbia University, Ray Fall of CU-Boulder and Monson. Fall, a professor of the chemistry and biochemistry department at CU-Boulder, said about 500 million tons of isoprene are emitted into Earth's atmosphere each year. The Southeast U.S. has large amounts of forest trees contributing to the isoprene emissions, said Fall, who also is a member with Monson at the CU-headquartered Cooperative Institute for Research in Environmental Sciences, or CIRES. CIRES is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration in Boulder. The CU-Boulder team's work, combined with research in the Biosphere II near Tucson, Ariz., primarily by Columbia University researchers, indicates it may be possible to genetically engineer environmentally friendly poplar trees by lessening their isoprene output, said Fall. "As almost all commercial agriforest species emit high levels of isoprene, proliferation of agriforest plantations has significant potential to increase regional ozone pollution and enhance the lifetime of methane, an important determinant of global climate," the researchers wrote in Nature. The Fall and Monson groups have been growing poplar trees in the chemistry and biochemistry department greenhouse in an attempt to isolate leaf cells and chloroplasts -- small bodies located inside plant cells that contain chlorophyll. They discovered that increases in CO2 in the laboratory caused the isoprene emissions from the leaf cells to decrease, a finding duplicated at the Biosphere II facility. They currently are working on a number of further research projects related to the isoprene activity, including inhibiting an enzyme inside the plant cells that appears to control the amount of isoprene emitted by trees.

Ozone Holes

January 6, 2003

https://www.sciencedaily.com/releases/2003/01/030106082326.htm

Scientists Discover Global Warming Linked To Increase In Tropopause Height Over Past Two Decades

LIVERMORE, Calif. -- Researchers at the Lawrence Livermore National Laboratory have discovered another fingerprint of human effects on global climate.Recent research has shown that increases in the height of the tropopause over the past two decades are directly linked to ozone depletion and increased greenhouse gases.

The tropopause is the transition zone between the lowest layer of the atmosphere -- the turbulently-mixed troposphere -- and the more stable stratosphere. The tropopause lies roughly 10 miles above the Earth's surface at the equator and five miles above the poles. To date, no scientist has examined whether observed changes in tropopause height are in accord with projections from climate model greenhouse warming experiments.The comparison was made by Livermore scientists Benjamin Santer, James Boyle, Krishna AchutaRao, Charles Doutriaux and Karl Taylor, along with researchers from the National Center for Atmospheric Research, NASA Goddard Institute for Space Studies, the Max-Planck Institute for Meteorology and the Institut für Physik der Atmosphäre in Germany. Their findings are reported in the today's (Jan. 3) online edition of the Journal of Geophysical Research-Atmospheres.This research undercuts claims by greenhouse skeptics that no warming has occurred during the last two decades. Such claims are based on satellite measurements of temperatures in the troposphere, which show little or no warming since the beginning of the satellite record in 1979. "Weather balloons and weather forecast models show that there's been a pronounced increase in the height of the global tropopause over the last two decades," Santer said. "Our best understanding is that this increase is due to two factors: warming of troposphere, which is caused by increasing greenhouse gases, and cooling of the stratosphere, which is mainly caused by depletion of stratospheric ozone. Tropopause height changes give us independent evidence of the reality of recent warming of the troposphere." The Livermore research supports the bottom-line conclusion of the 2001 Intergovernmental Panel on Climate Change (IPCC), which states that, "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."Earlier research showed that changes in the Earth's surface temperature, ocean heat content, and Northern Hemisphere sea ice cover are other indicators of human effects on climate change. "The climate system is telling us a consistent story -- that humans have had a significant effect on it," Santer said. "We're seeing detailed correspondence between computer climate models and observations, and this correspondence is in a number of different climate variables. Tropopause height is the latest piece of the climate-change puzzle."To support the research, Livermore scientists examined tropopause height changes in climate-change experiments using two different computer climate models. Both models showed similar decadal-scale increases in the tropopause height in response to changes in human-caused climate forcings. The patterns of tropopause height change were similar in models and so-called 'reanalysis' products (a combination of actual observations and results from a weather forecast model). The model experiments focused on both manmade climate forcings, such as changes in well-mixed greenhouse gases, stratospheric and tropospheric ozone, and on natural forcings, such as changes in volcanic aerosols. The forces have varying effects on atmospheric temperature, that in turn affect tropopause height, the report concludes.###Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

Ozone Holes

December 20, 2002

https://www.sciencedaily.com/releases/2002/12/021220075156.htm

Mercury In California Rainwater Traced To Industrial Emissions In Asia

SANTA CRUZ, CA -- Industrial emissions in Asia are a major source of mercury in rainwater that falls along the California coast, according to a new study by researchers at the University of California, Santa Cruz. The researchers reported their findings in a paper published online today by the Journal of Geophysical Research - Atmospheres. (The paper will appear in print in a later issue of the journal.)

The mercury in rainwater is not in itself a health threat, but mercury pollution is a significant problem in San Francisco Bay and other California waters because the toxic element builds up in the food chain. State regulatory agencies are looking for ways to reduce the amount of mercury entering the state's waters from various sources. The new study provides valuable information to guide those efforts, said Russell Flegal, professor and chair of environmental toxicology at UCSC and coauthor of the new paper. "People are talking about things like removing dental fillings before cremating bodies, but our analyses indicate that this may be a trivial source of mercury compared to the inputs from industrial emissions in Asia," Flegal said. Interestingly, it is not just the mercury itself but a whole cocktail of atmospheric pollutants that contribute to the deposition of mercury in rainfall. Elemental mercury behaves as a gas in the atmosphere and is not washed out in rain until it has been oxidized into a charged ionic form that can be captured by water droplets, said Douglas Steding, the paper's lead author. Ozone, a major component of urban and industrial smog, plays a key role in this oxidation process, said Steding, who did the study as a graduate student at UCSC and is now studying environmental law at the University of Washington. "There is a relatively large reservoir of mercury in the atmosphere, and it's the rate of oxidation that determines how much of it gets deposited in rainfall," he said. Mercury is a trace contaminant of most coal, and emissions from coal-burning power plants are a major source of mercury pollution in many parts of the world. In the Pacific Basin, the main source of atmospheric mercury is coal combustion in China. China relies heavily on coal as a fuel and accounts for about 10 percent of the total global industrial emissions of mercury. Air pollution in China also generates ozone, which peaks during the winter due to increased fuel consumption for heating. Air loaded with mercury and ozone moves off the continent into the Western Pacific, where it is incorporated into developing storms. "The mercury we measured in rainwater results from a combination of mercury emissions and ozone production, as well as meteorological factors--the storm tracks that transport the pollutants across the Pacific," Steding said. Steding collected rainwater samples at two sites in central California: on the coast at UCSC's Long Marine Laboratory and at Moffett Field near San Jose, on the inland side of the Santa Cruz Mountains. For each rainfall event, the researchers used air mass trajectories calculated by a national climate lab to trace the movement of the storms across the Pacific from Asia. Rainwater collected at the coastal site showed the background concentrations of mercury in storms as they arrived directly off the Pacific Ocean. Those measurements were about three times higher than estimates of the natural, preindustrial level, Steding said. Rainwater from the inland site showed mercury concentrations 44 percent higher than at the coastal site. Steding tentatively attributed the difference between the two sites mostly to ozone in Bay Area smog, rather than local emissions of mercury. "There is a local influence of urban smog on the mercury oxidation rate. We see a background signal of mercury blowing off the Pacific, then a local enrichment that's probably due to urban smog," he said. "If we want to reduce mercury deposition, it's not enough to shut down local emissions of mercury, because other pollutants influence how much of the mercury in the atmosphere ends up in rainwater." Steding emphasized that people should not worry about health effects from the mercury in rainwater, because the concentrations are very low. But the deposition in rain does add mercury to surface waters, where the toxin enters the food chain and builds up to high levels in certain kinds of fish. State health officials have issued advisories warning people not to eat fish from more than a dozen bodies of water in California, including San Francisco Bay. Much of the mercury contamination in California is the result of historic mining operations. Large amounts of liquid mercury were used in gold mining operations during the Gold Rush, leaving contaminated sediments throughout the vast watershed that ultimately drains into San Francisco Bay. In addition, Flegal's lab has shown that historic mercury mine sites in the Coast Ranges are still leaching mercury into rivers and streams that drain into San Francisco Bay. Prior to this new study, however, no one had looked at atmospheric transport of mercury from Asia as a source of mercury pollution on the U.S. West Coast, Flegal said.

Ozone Holes

November 4, 2002

https://www.sciencedaily.com/releases/2002/11/021101070716.htm

Fussy Microbe Holds Promise For Environmental Cleanup

EAST LANSING, Mich. – Scientists at Michigan State University have found an elusive microbe whose world-class pickiness is a key to one of the most nagging concerns in the cleanup of a common type of environmental toxin.

In this week's issue of Science, researchers from MSU's Center for Microbial Ecology report the discovery of a microbe dredged from the bottom of the Hudson River that has an insatiable appetite to break down the environmental pollutant TCA. "TCA was one of the remaining groundwater pollutants for which biodegradation had not been resolved," said James Tiedje, a University Distinguished Professor of microbiology and molecular genetics and of crop and soil sciences. "Till now, there wasn't good evidence there was a biodegradable solution." That means the bacterium shows promise as the missing piece of the puzzle to clean up soil and groundwater that is contaminated by multiple chlorinated solvents. Microbes that munch other toxins have been isolated, but TCA-eating bugs have remained a mystery. "For a while, people didn't think this bug existed," said postdoctoral student and co-author Baolin Sun. "Now we've solved it." TCA – 1,1,1-Trichloroethane – is a common industrial solvent that's found in half of the U.S. Superfund sites. As a pollutant, it packs a double punch, contaminating groundwater as well as eroding the ozone layer when released into the atmosphere. In the Science article "Microbial Dehalorespiration with 1,1,1-Trichloroethane," Tiedje's team identified TCA1, an anaerobic bacterium with a single-minded taste for TCA. "This is the first bacterium that breathes the chlorinated solvent TCA," said MSU doctoral student Benjamin Griffin. "It breathes TCA, and the only way we know how to grow the bacteria is to feed it TCA." The MSU group found TCA1 in the sediment of the upper Hudson River in New York. The bacterium also occurs naturally in Michigan's Kalamazoo River. TCA1 handily chows on the toxin, converting it to chloroethane, a less toxic substance that can then be easily degraded by aerobic microbes in soil. The beauty of the newly discovered bacterium is that it does its work under water, preventing the toxin from escaping into the atmosphere and causing ozone depletion. Finding TCA1 and understanding how to make it thrive is a first step in devising ways to put the bacterium to work cleaning up contaminated sites that until now were left with a piece of the puzzle unsolved.

Ozone Holes

October 1, 2002

https://www.sciencedaily.com/releases/2002/10/021001035852.htm

Unusually Small Ozone Hole Attributed To Strong Upper Level Weather Systems

Scientists from NASA and the Commerce Department's National Oceanic and Atmospheric Administration (NOAA) have confirmed the ozone hole over the Antarctic this September is not only much smaller than it was in 2000 and 2001, but has split into two separate "holes."

The researchers stressed the smaller hole is due to this year's peculiar stratospheric weather patterns and that a single year's unusual pattern does not make a long-term trend. Moreover, they said, the data are not conclusive that the ozone layer is recovering. Paul Newman, a lead ozone researcher at NASA's Goddard Space Flight Center, Greenbelt, Md., said this year, warmer-than-normal temperatures around the edge of the polar vortex that forms annually in the stratosphere over Antarctica are responsible for the smaller ozone loss. Estimates for the last two weeks of the size of the Antarctic Ozone Hole (the region with total column ozone below 220 Dobson Units), from the NASA Earth Probe Total Ozone Mapping Spectrometer (EPTOMS) and the NOAA-16 Solar Backscatter Ultraviolet instrument (SBUV/2), are around 15 million square kilometers (6 million square miles). These values are well below the more-than 24 million sq. km. (9 million sq. mi.) seen the last six years for the same time of year. The stratosphere is a portion of the atmosphere about 6-to-30 miles above the Earth's surface where the ozone layer is found. The ozone layer prevents the sun's harmful ultraviolet radiation from reaching the Earth's surface. Ultraviolet radiation is a primary cause of skin cancer. Without protective upper-level ozone, there would be no life on Earth. "The Southern Hemisphere's stratosphere was unusually disturbed this year," said Craig Long, meteorologist at NOAA's Climate Prediction Center (CPC). The unusual weather patterns were so strong, the ozone hole split into two pieces during late September. NOAA's CPC has been monitoring and studying the ozone since the early 1970s. "This is the first time we've seen the polar vortex split in September," said Long. At South Pole Station, balloon-borne ozone-measuring instruments launched by NOAA's Climate Monitoring and Diagnostics Laboratory (CMDL) reveal the vertical structure of the developing ozone hole. Bryan Johnson, a scientist with CMDL, said the main ozone depletion region, from 7-to-14 miles above the Earth, has large ozone losses, similar to the last few years. At more than 15 miles above the Earth, surface measurements show higher-than-normal ozone concentrations and higher temperatures. The combination of these layers indicate total ozone levels in a column of atmosphere will be higher than observed during the last few years, Johnson said. However, some layers may still show complete ozone destruction by early October, when ozone depletion is greatest. In 2001, the Antarctic ozone hole was larger than the combined area of the United States, Canada and Mexico. The last time the ozone hole was this small was in 1988, and that was also due to warm atmospheric temperatures. "While chlorine and bromine chemicals cause the ozone hole, temperature is also a key factor in ozone loss," Newman said. The Montreal Protocol and its amendments banned chlorine-containing chlorofluorocarbons (CFCs) and bromine-containing halons in 1995, because of their destructive effect on the ozone layer. However, CFCs and halons are extremely long-lived and still linger at high concentrations in the atmosphere. The coldest temperatures over the South Pole typically occur in August and September. Thin clouds form in these cold conditions, and chemical reactions on the cloud particles help chlorine and bromine gases to rapidly destroy ozone. By early October, temperatures usually begin to warm, and thereafter the ozone layer starts to recover. NOAA and NASA continuously observe Antarctic ozone with a combination of ground, balloon, and satellite-based instruments.

Ozone Holes

June 26, 2002

https://www.sciencedaily.com/releases/2002/06/020626070834.htm

Researchers Pursue Process By Which Oak Trees Contribute To Air Pollution

COLLEGE STATION - Trees may not actually commit suicide, but certain species do produce pollutants that hamper their own growth while contributing to global climate changes and causing harm to other life forms, contend two Texas A&M University researchers.

Renyi Zhang, an atmospheric chemist, is studying one such substance, isoprene, given off by oak trees and leading to increased ozone in our atmosphere. Working under a $300,000 grant from the National Science Foundation, Zhang and chemistry professor Simon North have taken on the challenge of unraveling the more than 1,000 reactions that transform organically released isoprene into toxic atmospheric pollutants. "Air pollution is probably one of the most serious problems facing humankind in the 21st century," said Zhang, a professor in the College of Geosciences. "And certainly, much of that pollution results from human activities. But most people are not aware of the role played by chemical reactions which change substances produced by biogenic species into harmful airborne pollutants. "Isoprene - C5H8 - is released by the respiration of oak trees and is the second-most abundant naturally produced hydrocarbon (after methane) in our atmosphere," he continued. "After a complicated series of chemical reactions, isoprene facilitates ozone production, so increased isoprene means more ozone in the air." Ozone in the upper atmosphere blocks out harmful ultraviolet radiation from the sun, Zhang explained, but nearer the ground, it traps infrared radiation reflected back up from Earth and contributes to heating the air near the planet's surface, the so-called "Greenhouse Effect." So, more ozone can mean rising temperatures near ground-level, contributing to global warming. "Although near-ground ozone has some beneficial effects, providing excited oxygen atoms needed to produce the free OH radicals that help to bind other chemicals like sulfur and cleanse them from the atmosphere, excess ozone proves harmful to the health of humans and plants," Zhang said. "For example, too much ozone can retard tree growth or even kill trees. And if too many trees die, there will be more CO2 in the air, further trapping heat and raising the temperature of the planet." Zhang and North are studying isoprene oxidation related to oak trees in the Houston area, where ozone is contributing to increasing air pollution. They are seeking to understand the critical reactions out of the 1,000 in the isoprene to ozone chain in order to find ways to abate air pollution and allow trees to continue their life-cycle without increasing environmental damage. Zhang will be using laboratory apparatus to study isoprene using chemical ionization mass spectrometry, while North will look at the chemical process using laser-induced fluorescence. Both researchers also employ methods of quantum chemical calculation to analyze their experimental results. In addition to the NSF grant, their work is being funded by the Welch Foundation, the Texas Advanced Research Program (Chemistry) and the U.S. Department of Energy (DOE). "The isoprene chain reaction is very complicated - in fact, it's been studied for over 30 years without significant results with regard to fundamental details," said Zhang. "Dr. North and I seeking to discover the direction in which reaction pathways proceed. If we can fully understand the critical steps in the reaction, maybe we can determine where best to intervene in the process to keep both our oak trees and ourselves healthier."

Ozone Holes

June 19, 2002

https://www.sciencedaily.com/releases/2002/06/020619074058.htm

New Study Sheds Light On Frog Malformations

The emergence of mutant frogs with extra arms and legs may smack of a low-budget sci-fi script. But it is a reality, and a new study provides more evidence that ultraviolet radiation could be responsible. The findings are reported in three consecutive papers in the July 1 print issue of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society. Concern has been mounting for years over the depletion of the ozone layer — the atmospheric shield that helps block harmful ultraviolet (UV) radiation from reaching the Earth's surface. At the same time amphibian populations have been declining, and many have been turning up with unusual malformations, such as missing or extra limbs.

A number of causes have been suggested to explain the malformations, including exposure to chemicals and parasites. Only recently have researchers been examining the potential connection to UV radiation to determine if it is coincidence or something more. Until now, most of the research has focused on exposing frogs to UV radiation in the laboratory, providing little information about how these findings translate to natural habitats. "We really wanted to fill the gap between the findings of other laboratory research and what might happen in natural environments," said Steve Diamond, Ph.D., an environmental toxicologist at the United States Environmental Protection Agency in Duluth, Minn., and an author on all three papers. In the first study, Diamond and his colleagues kept frog eggs in small outdoor containers while exposing them to varying degrees of UV radiation — from 25 to 100 percent of natural sunlight. As the eggs developed, the researchers observed hatching success, tadpole survival and the presence of malformations. They found that the frequency of malformations increased with increasing UV radiation, with half of the frogs experiencing malformations at 63.5 percent of the intensity of natural sunlight. This supplements data from a previously published paper, which reported that 100 percent sunlight reduces survival by an average of 50 percent. In the course of these experiments, the researchers also determined that a specific region of the UV spectrum, known as UVB, appears to cause the malformations. In the real world, however, frogs rarely experience 100 percent of natural sunlight. A variety of environmental factors conspire to reduce the levels of UV radiation entering wetlands, including ozone levels, cloud cover and UVB-absorbing dissolved organic carbon (DOC) in water. Accordingly, in the second study, the researchers measured DOC levels in wetlands in Wisconsin and Minnesota and found that the top five to 20 centimeters of wetlands absorb as much as 99 percent of UVB. To complete the picture, the third study involved a survey of 26 wetlands in the same region to estimate the specific level of risk of frogs living in these environments. Using a combination of computer models, historical weather records and DOC measurements, they concluded that UVB posed a risk to amphibians living in three of the 26 wetlands. While these findings suggest that most frogs are not currently at risk for UVB effects in this area of the country, the possibility of effects on amphibians in general should not be completely ignored, according to Diamond. Continued reduction of ozone and other global climate change effects may increase UV exposure in wetlands, suggesting that the potential risk to amphibians should continue to be studied. Diamond's team and a group of researchers from the National Parks are presently evaluating UVB levels across landscapes to compare them with the occurrence or absence of amphibians. "Those results," Diamond said, "combined with the risk assessment presented in these three manuscripts, will add significantly to our understanding of the relationship between UVB levels and amphibian declines or malformations."

Ozone Holes

June 6, 2002

https://www.sciencedaily.com/releases/2002/06/020606075647.htm

Climate Change May Become Major Player In Ozone Loss

While industrial products like chlorofluorocarbons are largely responsible for current ozone depletion, a NASA study finds that by the 2030s climate change may surpass chlorofluorocarbons (CFCs) as the main driver of overall ozone loss.

Drew Shindell, an atmospheric scientist from NASA's Goddard Institute for Space Studies (GISS) and Columbia University, N.Y., finds that greenhouse gases like methane and carbon dioxide are changing the climate in many ways. Some of those effects include water vapor increases and temperature changes in the upper atmosphere, which may delay future ozone recovery over heavily populated areas. Scientists have expected the ozone layer to recover as a result of international agreements to ban CFCs that destroy ozone. CFCs, once used in cooling systems and aerosols, can last for decades in the upper atmosphere, where they break down, react with ozone, and destroy it. They remain the major cause of present-day ozone depletion. "It's hard to tell if those great international agreements [to ban CFCs] work if we don't understand the other big things that are going on in the stratosphere, such as increases in greenhouse gases and water vapor," Shindell said. The stratosphere is a dry atmospheric layer between 6 and 30 miles (9.7 and 48.3 kilometers) up where most ozone exists. Ozone shields the planet's surface from the Sun's harmful ultraviolet radiation and makes life on Earth possible. The study examined the ozone layer over heavily populated areas around the equator and mid-latitudes where ozone thinning occurs, excluding the Polar regions, where 'ozone holes' form. Ozone thinning can occur when increased emissions of methane get transformed into water in the stratosphere. At high altitudes, water vapor can be broken down into molecules that destroy ozone. Also, methane and carbon dioxide change our climate by trapping heat in the atmosphere before it can escape out to space. This greenhouse effect, much like the inside of a car with all the windows closed, heats the air within the lowest layer of the atmosphere, called the troposphere. Warming in the troposphere can alter atmospheric circulation and make the air wetter, since warmer air holds more water. Though complex and not well understood, there is evidence that water vapor can get wafted from the troposphere into the stratosphere by shifting air currents caused by climate change.

Ozone Holes

May 29, 2002

https://www.sciencedaily.com/releases/2002/05/020529071845.htm

Ozone Losses May Be Speeding Up At Higher Latitudes, According To University Of Colorado Study

New findings by University of Colorado at Boulder researchers indicate ozone losses due to the breakdown of chlorofluorocarbons, or CFCs, occur much faster than previously believed at higher latitudes roughly 10 miles above Earth.

Associate Professor Darin Toohey of the Program in Atmospheric and Oceanic Sciences said scientists have known for several decades that chlorofluorocarbon-derived compounds can deplete stratospheric ozone. More recently, some have proposed that adverse chemical reactions caused by man-made compounds occurring just seven to 10 miles in altitude could lead to additional ozone losses. While such chemical reactions at lower altitudes may be occurring, “What we see is that ozone-depleting reactions of chlorine and bromine compounds are occurring rapidly at high latitudes in winter,” he said. The winter chemical reactions are occurring in an atmospheric region where the air can readily mix with air at mid-latitudes like the skies over Reno, Denver and Philadelphia. PAOS researchers and students have used balloons and aircraft to show that ozone-gobbling chlorine “free radicals” produced by the breakdown of CFCs are more concentrated at high latitudes than previously believed. During winter and spring, the reactions appear to be accelerated from about 50 degrees to 60 degrees in latitude – roughly from Vancouver, B.C., north to Great Slave Lake in the Northwest Territories –all the way to the North Pole. These chemical reactions occur in regions where there are ice clouds, based on measurements of CU-Boulder Professor Linnea Avallone of PAOS and the Laboratory for Atmospheric and Space Physics, said Toohey. Toohey presented his research at the Spring American Geophysical Union Meeting on May 28 in Washington, D.C. The invisible ozone layer, which shields Earth from harmful ultraviolet radiation, is produced naturally in the stratosphere -- 10 miles to 30 miles above Earth’s surface. Until several decades ago, the equilibrium of the layer has been maintained by several competing chemical reactions among naturally occurring oxygen and hydrogen molecules. “This ozone-depleting chemistry is important because it occurs outside the region where large amounts of ozone depletions have previously been reported, such as the poles and at higher altitudes,” said Toohey. While ozone losses at higher altitudes inside the polar vortex are thought to be confined to the high latitudes, it is possible that transport and mixing of lower-altitude air is having a wider influence on ozone abundance at lower latitudes. In addition, new studies from Boulder scientist Stephen Reid of the National Oceanic and Atmospheric Administration suggest climate change could alter the motion of air in the lower stratosphere. “These results raise the possibility that halogen chemistry occurring at high latitudes is more important for ozone trends at mid-latitudes than was previously believed,” said Toohey.

Ozone Holes

May 17, 2002

https://www.sciencedaily.com/releases/2002/05/020517075920.htm

Human Activity Raises Level Of Sulfur Gas That Affects Ozone Layer, Researchers Say

WASHINGTON - The most abundant sulfur gas in the lowest layer of the Earth's atmosphere is carbonyl sulfide. While carbonyl sulfide is formed naturally, it is also produced through a chemical reaction in the atmosphere involving carbon disulfide, a chemical produced by a variety of industrial processes.

Human-produced carbonyl sulfide has attracted attention as a possible source of increased levels of sulfate particles, or aerosols, in the atmosphere, which have been linked to depletion of the ozone layer. Sulfate aerosols also influence global climate, causing cooling effects by scattering incoming solar rays and reducing the amount of radiation that reaches the Earth. New estimates obtained from ice core samples collected from the Siple Dome, West Antarctica, suggest that human activities have contributed approximately 25 percent of the modern carbonyl sulfide in the atmosphere. The results of the study, based on the first such measurements taken from ice, by Murat Aydin and colleagues at the University of California at Irvine, are published this month in the journal, Geophysical Research Letters, published by the American Geophysical Union. The collected ice core samples provide researchers with an archive of air from 1616 to 1694, allowing them to determine the concentration of carbonyl sulfide prior to industrial inputs. To collect air trapped within the ice, the researchers crushed the eleven core samples within a vacuum. The samples were then analyzed to obtain a mean carbonyl sulfide mixing ratio, or concentration of carbonyl sulfide in the sample, expressed in parts per trillion by volume (pptv), over the 78-year period. This pre-industrial mixing ratio is approximately three-quarters that of the modern carbonyl sulfide mixing ratio, suggesting that approximately 25 percent of the modern atmospheric carbonyl sulfide is generated through human activity. The researchers also found no loss of carbonyl sulfide from the ice cores over time. This means that with further measurements, it should be possible to generate a record of atmospheric carbonyl sulfide concentrations further back through time, and allow researchers to develop a baseline against which to measure current carbonyl sulfide levels. Because the gas is generated both naturally and through human activities, a baseline would help scientists assess the effect of human activity on carbonyl sulfide, and ultimately sulfate aerosols, in the upper atmosphere. The researchers also note that developing a paleoatmospheric record of carbonyl sulfide will allow them to better understand the natural variability associated with the complicated sources and sinks of carbonyl sulfide, and to study how climate influences biogeochemical cycles over time. This research was supported by the National Science Foundation.

Ozone Holes

May 15, 2002

https://www.sciencedaily.com/releases/2002/05/020514073636.htm

NASA Study Leads To Better Understanding Of Ozone Depletion

Scientists have unraveled a mystery about hydrogen peroxide that may lead to a more accurate way of measuring a gas that contributes to depletion of Earth's protective ozone layer.

Scientists have long known that reactive hydrogen gases destroy stratospheric ozone. Too little ozone may lead to unwelcome changes in climate and to more ultraviolet radiation reaching Earth's surface. Ideally, atmospheric scientists would like to make global maps of the distribution of these gases, because there is increasing concern that their abundances may be rising due to increases in stratospheric humidity. These gases - comprising hydroxyl (OH) and hydroperoxyl (HO2) -- cannot be easily measured from space, but a product of their reaction, hydrogen peroxide, is detectable. However, a large, nagging discrepancy has existed between computer models of hydrogen peroxide abundance and actual atmospheric measurements, suggesting that a complete understanding of the chemistry has been lacking. Now scientists from NASA's Jet Propulsion Laboratory, Pasadena, Calif., the California Institute of Technology in Pasadena and the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. have resolved much of this disparity. The results could ultimately allow concentrations of reactive hydrogen gas to be inferred by monitoring hydrogen peroxide from space or the ground. "We're trying to improve our understanding of the atmosphere well enough to be able to model ozone depletion and climate change in general," says JPL researcher Dr. Stan Sander, one of the authors of the laboratory study performed at JPL. "This work provides a tool for better understanding what's going on in the climate system." In research published May 7 in the journal Geophysical Research Letters, the scientists found that previous measurements of the rate of hydrogen peroxide formation, which were based upon a model that used standard photochemical parameters, were too high—by a factor of two. Their finding largely reconciles previous measurements and model calculations of hydrogen peroxide in the upper atmosphere. Atmospheric chemists had long puzzled over why models could not correctly predict hydrogen peroxide concentrations, but had not suspected the rate for forming hydrogen peroxide, thought to be well known, could be in error. Lance Christensen, a Caltech graduate student in chemistry working at JPL and lead author of the paper, showed that at low temperatures relevant to the stratosphere, processes other than the central reaction—specifically a complication caused by the presence of methanol in laboratory tests—were compromising prior studies. The new information led to a change in a key rate parameter that provides input to the photochemical model used to examine aircraft, balloon and satellite data. When the researchers applied the new laboratory rate for hydrogen peroxide formation to measured hydrogen peroxide levels from two different interferometer instruments flying aboard high-altitude research balloons as part of NASA's Upper Atmospheric Research Program, measured and modeled hydrogen peroxide levels were in agreement. The high degree of agreement between the two instrument measurements led the researchers to believe the discrepancy was not due to measurement error. Dr. Mitchio Okumura, an associate professor of chemistry at Caltech and one of the authors of the study, said that while the new rate of hydrogen peroxide formation has no appreciable impact on stratospheric ozone loss rates, the finding does open the possibility for remote measurement of hydrogen peroxide to infer reactive hydrogen gas radicals. "These gases are really central to the chemistry of the stratosphere and upper troposphere in understanding ozone depletion," he said. "Measurements of hydrogen peroxide will likely provide the best means of obtaining global maps of these gases in these regions of the atmosphere, because direct space-borne measurement of them below about 20 kilometers (12.4 miles) in altitude is quite challenging." Dr. Ross Salawitch, an atmospheric chemist at JPL and a co-author of the study, said the research has important implications for future studies of ozone depletion. "The majority of observed ozone depletion over the past two decades was caused by the buildup of industrially-produced chlorofluorocarbons, he said. "As a result of the worldwide ban on chlorofluorocarbon production, Earth's atmosphere will cleanse itself of these gases over the next 50 to 100 years. Recently, however, scientists have become increasingly concerned that changes in Earth's climate could lead to increased levels of water in the stratosphere. This could lead to additional ozone depletion by reactive hydrogen gases, which are a byproduct of water. Our study addresses this concern, allowing scientists to monitor this process in the future." In addition to Okumura, Sander, Christensen and Salawitch, the other authors include Drs. Geoffrey Toon, Bhaswar Sen, and Jean-Francois Blavier, all of JPL; and Dr. K.W. Jucks of the Harvard-Smithsonian Center for Astrophysics. This research was funded as part of NASA's Earth Science Enterprise, a long-term research effort dedicated to understanding and protecting our home planet. Through the study of Earth, NASA will help to provide sound science to policy and economic decision makers so as to better life here, while developing the technologies needed to explore the universe and search for life beyond our home planet. JPL is a division of the California Institute of Technology.

Ozone Holes

April 22, 2002

https://www.sciencedaily.com/releases/2002/04/020422073508.htm

USC Researchers Find Ozone Lowers Sperm Counts

RANCHO MIRAGE, CA, April 19, 2002 –– Ozone appears to be harmful to male fertility, according to Keck School of Medicine of USC researcher Rebecca Z. Sokol, M.D., a professor of obstetrics and gynecology and medicine. The high ozone levels produced in the lower atmosphere—the result of the release of pollutants—seems to be linked to lower sperm counts and decreased sperm motility in otherwise healthy, fertile men.

Sokol reported on this work at the annual meeting of the Pacific Coast Reproductive Society. She and her colleagues analyzed more than 8,000 sperm samples donated by 50 men in the Los Angeles area over a three-year period (January 1996 to December 1998), and compared them to more than 3,500 samples donated by 35 men from Northern California over the same time. The original idea, says Sokol, was to see if there were geographic differences between the groups in terms of sperm quality. But, she says, the results were rather disappointing. "We found only minimal differences between Northern and Southern California, with only marginally higher motile sperm counts in Southern California," she reports. "And we weren’t even sure if those were real; there may very well have been some confounding factors." But when she and her Keck colleagues compared the sperm data with air quality data donated by a private entrepreneur at Sonoma Technologies in Petaluma, Calif., they were startled by the pattern that emerged. "There was a significant correlation," says Sokol, "between decreases in sperm count and motility and increased ozone levels in the air, especially in Southern California." In 2000, Sokol reported that sperm counts in general have remained virtually unchanged over the past 50 years, despite reports that the lives of men in the modern world were leading to a reduction in virility by as much as 50 percent. This sort of epidemiology-based work is new to Sokol, who spent most of her career researching the effects of toxicants on male reproduction and infertility, and working in clinical studies in the field of male infertility. Then, in 2001, she was awarded a National Institutes of Health senior investigator fellowship award. Her award is supported by the National Institute of Environmental Health Sciences. Just how ozone might be affecting sperm quality is somewhat of a conundrum, Sokol admits. "The blood-testis barrier is supposed to protect from these bad things," she says. [The cells lining the seminiferous tubules in the testes isolate sperm cells from the immune cells in the blood so as to prevent the body from launching an immune attack against the sperm, and to protect the sperm from any toxins in the blood.] "We know that oxygen radicals interfere with sperm function in the laboratory. So the question is, what physiological response does ozone inhalation trigger to affect sperm in the body?" Sokol hopes to investigate that very question. In addition, she says, she would like to do another study of sperm quality—this one prospective rather than retrospective, and looking at sperm samples from a number of major cities known to have significant increases and decreases in ozone levels, such as New York and Mexico City. "I’m really starting to branch out," she says. "This is such a new area for me, and there’s so much to learn."

Ozone Holes

April 17, 2002

https://www.sciencedaily.com/releases/2002/04/020417065937.htm

Improved Ozone Monitoring Technology Expected To Improve Smog Forecasting

Knowing the concentration of ozone in the air above urban areas is a missing piece of important information for ozone pollution forecasters.

Atmospheric scientists studying ozone pollution also need this information to help determine the "sources and sinks" (i.e., where it is created and where it goes) of air pollutants. In turn, metro area planners could devise effective strategies to address air quality issues. With these ultimate goals in mind, a team of engineers at the Georgia Tech Research Institute (GTRI) is designing the next generation of ozone-monitoring technology. Based on light detection and ranging (LIDAR) technology developed by the National Oceanic and Atmospheric Administration, the new version will make ozone monitoring continuous and affordable, and results will be available via the Internet in real time. Funded by a Technology Development Partnership through the Georgia Research Alliance and LaserCraft Inc. of Norcross, Ga., the device has been dubbed NEXLASER for NEXt Generation Laser Air Sensor for the Southeastern Region (though the technology could be applied anywhere in the world). "NEXLASER will be great for ozone forecasting, and it should enable people to do new kinds of research projects in city planning, environmental engineering and atmospheric chemistry," said GTRI project director Gary Gimmestad. "?. Right now, it's hard to correlate anything like traffic patterns with ozone. It's just not accurate yet because there's not enough information." NEXLASER will adapt and automate the operation of LIDAR, which in the past has been suitable only for short-term studies because it requires numerous personnel to operate it. LIDAR works like this: 1) A laser emits pulses of light that scatter into the atmosphere. 2) Then a telescope receives that scattered light. 3) A detector converts the light to electronic signals. 4) A data system digitizes and stores those signals. 5) Finally, researchers determine the distance the light scattered by multiplying the speed of light by the flight time it took the pulse to travel up and back. This information reveals the ozone concentration at periodic measured distances because ozone absorbs one color of light emitted from the laser, but not another. So a dense concentration of ozone would lessen the distance light scatters. While LIDAR provides significant data, it is usually not automated. It takes a crew of operators to make adjustments, maintain the system, and collect and analyze data. NEXLASER will automate this process, making data collection continuous and data analysis occur in real time. "NEXLASER's three-dimensional data -- altitude up to 3 kilometers, ozone concentration and geographic distribution from a network of units -- will represent a significant technological improvement," Gimmestad said. "We hope that knowing the ozone concentration in all of these places can improve researchers' understanding of ozone sources and sinks." Senior research scientist Michael Chang in the Georgia Tech School of Earth and Atmospheric Sciences is hopeful about NEXLASER. "If they can pull this off and get a unit that is affordable, it would be great," Chang said. "We can do this type of monitoring now, but it requires a $2 million investment. If they can get the cost down to about a quarter of a million, it's still costly, but we can handle that. "Vertical profiles of air quality are the great unknown. All of the air quality monitoring we do now is essentially at the surface. But what's above the surface is extremely critical in terms of the air quality at the surface, particularly in the late afternoon. NEXLASER could be the single greatest improvement to our ozone forecasting at this time?. We're looking forward to it with great anticipation," Chang added. Researchers have completed a laboratory version of NEXLASER and a prototype of software to automate data analysis. They recently began operating, testing and evaluating the system in their lab. The next phase, which may begin this summer, will be field-testing. After that, researchers would work with LaserCraft engineers in developing a commercial version of NEXLASER, which would cost about $250,000 per unit. Gimmestad hopes a network of six NEXLASER units will be deployed within two years at Georgia Environmental Protection Division field sites around metro Atlanta. "Atlanta is the perfect test case for a NEXLASER network," Gimmestad said. "It has the third-worst air quality in the nation after Los Angeles and Houston?. We hope the NEXLASER technology would be adopted by other cities within five years." Meanwhile, much work must be done in the lab, the field and the commercial arena. Because LaserCraft is funding part of the NEXLASER research, it has the rights to license the technology. Georgia Tech would grant an actual license to LaserCraft after Gimmestad's team completes field-testing. "LaserCraft is very pleased to sponsor this project for a number of reasons," said Glen P. Robinson Jr., CEO of LaserCraft. "It fits into our long-range plans to develop new products around laser technology. The NEXLASER will help solve a serious air pollution problem, and it will provide many new, high-tech employment opportunities for Georgia citizens." LaserCraft's major products are laser speed guns used for traffic speed control, monitoring violations at traffic lights and stop signs, and identifying speeders in school zones and residential areas, and a line of laser-based surveying instruments. The Georgia Research Alliance is also hopeful about the prospects for NEXLASER. "It brings together Georgia Tech's research and development strengths with LaserCraft's success in marketing and selling laser-based technology," said Kathleen Robichaud, program manager for GRA. And it has real potential for helping to address very serious air quality problems." The other GTRI researchers involved with the study are project lead engineer Dave Roberts, and engineers John Stewart, Leanne Little West and Jack Wood.

Ozone Holes

March 6, 2002

https://www.sciencedaily.com/releases/2002/03/020306073904.htm

Future Volcanic Eruptions May Cause Ozone Hole Over Arctic

An "ozone hole" could form over the North Pole after future major volcanic eruptions, according to the cover story by a NASA scientist in tomorrow's edition of the Proceedings of the National Academy of Sciences.

Since the 1980s a seasonal ozone hole, characterized by severe loss of ozone, has appeared over the continent of Antarctica. However, scientists have not yet observed, on an annual basis, as severe a thinning of the protective ozone layer in the atmosphere over the Arctic. The ozone layer shields life on Earth from harmful ultraviolet radiation. A northern ozone hole could be significant since more people live in Arctic regions than near the South Pole. "A 'volcanic ozone hole' is likely to occur over the Arctic within the next 30 years," said Azadeh Tabazadeh, lead author of the paper and a scientist at NASA's Ames Research Center, Moffett Field, Calif. Her co-authors are: Katja Drdla, also of Ames; Mark R. Schoeberl of NASA's Goddard Space Flight Center, Greenbelt, Md.; Patrick Hamill of San Jose State University, Calif.; and O. Brian Toon from the University of Colorado, Boulder. "If a period of high volcanic activity coincides with a series of cold Arctic winters, then a springtime Arctic ozone hole may reappear for a number of consecutive years, resembling the pattern seen in the Antarctic every spring since the 1980s," Tabazadeh said. "Unlike the Antarctic where it is cold every winter, the winter in the Arctic stratosphere is highly variable," Tabazadeh said. NASA satellite and airborne observations show that significant Arctic ozone loss occurs only following very cold winters, according to Tabazadeh. Large volcanic eruptions pump sulfur compounds into the Earth's atmosphere. These compounds form sulfuric acid clouds similar to polar stratospheric clouds made of nitric acid and water. The clouds of nitric acid and water form in the upper atmosphere during very cold conditions and play a major part in the destruction of ozone over Earth's poles. Following eruptions, volcanic sulfuric acid clouds would greatly add to the ozone-destroying power of polar stratospheric clouds, researchers said. "Volcanic aerosols also can cause ozone destruction at warmer temperatures than polar stratospheric clouds, and this would expand the area of ozone destruction over more populated areas," Tabazadeh said. "Nearly one-third of the total ozone depletion could be a result of volcanic aerosol effects at altitudes below about 17 kilometers (11.5 miles)," said the researchers. "Volcanic emissions can spread worldwide," said Schoeberl. "Our Mt. Pinatubo computer simulation shows that the volcanic plume spread as far north as the North Pole in the lowest part of the stratosphere within a few months after the eruption." Between about 15 and 25 kilometers (9 to 16 miles) in altitude, volcanic Arctic clouds could increase springtime ozone loss over the Arctic by as much as 70 percent, according to Drdla. "The combination of thick volcanic aerosols at lower altitudes and natural polar stratospheric clouds at higher altitudes could greatly increase the potential for ozone destruction over the North Pole in a cold year," Tabazadeh said. "Both the 1982 El Chichon and 1991 Mt. Pinatubo eruptions were sulfur-rich, producing volcanic clouds that lasted a number of years in the stratosphere," Tabazadeh said. The Pinatubo eruption, as observed by NASA spacecraft, widely expanded the area of ozone loss over the Arctic. Both of these eruptions did have an effect, however, over the South Pole, expanding the area and the depth of the ozone hole over the Antarctic, according to Tabazadeh. Computer simulations have shown that the early and rapid growth of the Antarctic ozone hole in the early 1980s may have been influenced in part by a number of large volcanic eruptions, she added. "In 1993 the Arctic winter was not one of the coldest winters on record, and yet the ozone loss was one of the greatest that we've seen," Tabazadeh said. "This was due to the sulfurous Pinatubo clouds facilitating the destruction of additional ozone at lower altitudes where polar stratospheric clouds cannot form." "Climate change combined with aftereffects of large volcanic eruptions will contribute to more ozone loss over both poles," Tabazadeh said. "This research proves that ozone recovery is more complex than originally thought."

Ozone Holes

February 25, 2002

https://www.sciencedaily.com/releases/2002/02/020221073102.htm

Increased Water Vapor In Stratosphere Possibly Caused By Tropical Biomass Burning

New Haven, Conn. - The doubling of the moisture content in the stratosphere over the last 50 years was caused, at least in part, by tropical biomass burning, a Yale researcher has concluded from examining satellite weather data.

Tropical biomass burning is any burning of plant material. In the tropics this is usually the clearing of forest or grassland for agricultural purposes, mostly before the growing season."In the stratosphere, there has been a cooling trend that is now believed to be contributing to milder winters in parts of the northern hemisphere; the cooling is caused as much by the increased humidity as by carbon dioxide," said Steven Sherwood, assistant professor of geology and geophysics whose article appears in this month's issue of the journal, Science. "Higher humidity also helps catalyze the destruction of the ozone layer."Cooling in the stratosphere causes changes to the jet stream that produce milder winters in North America and Europe. By contrast, harsher winters result in the Arctic.Sherwood said that about half of the increased humidity in the stratosphere has been attributed to methane oxidation. It was not known, however, what caused the remaining added moisture.In a study funded by the National Aeronautics and Space Administration, Sherwood examined a combination of data from a NASA satellite launched in the 1990s and operational weather satellite data archived at the Goddard Institute for Space Science in New York.In particular, he studied monthly and yearly fluctuations of humidity in the stratosphere, relative humidity near the tropical tropopause, which is the place where air enters the stratosphere, ice crystal size in towering cumulus clouds, and aerosols associated with tropical biomass burning."More aerosols lead to smaller ice crystals and more water vapor entering the stratosphere," Sherwood said. "Aerosols are smoke from burning. They fluctuate seasonally and geographically. Over decades there have been increases linked to population growth."

Ozone Holes

February 21, 2002

https://www.sciencedaily.com/releases/2002/02/020220075850.htm

Pinatubo Volcano Research Boosts Case For Human-Caused Global Warming

NEW BRUNSWICK/PISCATAWAY, NJ – Research into the worldwide climatic impact of the 1991 Mount Pinatubo volcanic eruption during the 10 years since the eruption has strengthened the case for human causes of global warming, a Rutgers scientist reports in a paper published in the February 14 issue of the international journal, Science.

The Pinatubo research also has improved scientists' ability to forecast the impact of future volcanoes on weather and climate, says the paper's author, Alan Robock of the university's Center for Environmental Prediction in the Department of Environmental Sciences, Cook College.According to Robock, the eruption on Luzon Island in the Philippines on June 15, 1991 produced the largest volcanic cloud of the 20th century and caused changes in worldwide climate and weather that were felt for years.The changes wrought by Pinatubo's sulfuric acid cloud, which blocked a large percentage of sunlight from reaching the earth, initially included cooler summers and warmer winters, an overall net cooling at the earth's surface and altered winds and weather patterns, Robock said.In certain areas such as the Middle East, it produced a rare snowstorm in Jerusalem and led to the death of coral at the bottom of the Red Sea, he noted.The cloud also caused depletion of the ozone layer over Temperate Zone regions of the Northern Hemisphere where much of the world's population resides, in addition to the regular ozone "hole" which appears in October over Antarctica, the researcher said.Most significant, the scientist said, Pinatubo helped validate computer-generated climate models that demonstrate human-caused global warming.Using computer modeling, said Robock, scientists have been able to account for natural warming and cooling, as found in Arctic and Antarctic ice core samples and tree rings covering hundreds of years up to the last century."If you plug in volcanic eruptions, El Niños, solar variations and other natural causes and try to simulate past climate changes, you can do a pretty good job of modeling climate change until the end of the 19th Century," the researcher said.After that period, he said, natural causes alone don't account for the amount of warming, about 0.6 degrees Celsius (1.1 degrees Fahrenheit), that has taken place in the last century."But when you factor in Pinatubo and other eruptions along with anthropogenic (human-caused) emissions," said the scientist, "it accounts for the observed record of climate change for the past century, including the overall warming and episodic cooling, and validates the climate models."In addition to improving understanding of global warming, scientists will be able to develop better seasonal forecasts after the next major eruption occurs, he noted. "Although overall the planet cools after volcanic eruptions, over Northern Hemisphere continents it actually gets warmer in the winter. This is because the wind patterns change in response to heating of the stratosphere by the volcanic aerosols."The ozone layer, which protects against the sun's life-damaging ultraviolet radiation, developed a hole over the South Pole during the last century due to human activity -- chlorofluorocarbons (freons) from refrigeration, air conditioning, and industrial processes, noted the researcher.Because the Antarctic region is so cold, clouds are able to form in the stratosphere, Robock said. The cloud particles serve as surfaces to allow sunlight to catalyze chemical reactions involving chlorine and bromine pollutants that destroy ozone, he noted.The Mount Pinatubo cloud provided a similar surface on sulfuric acid particles for pollutants to react with sunlight and destroy ozone over Temperate Zone regions of the globe, not just over the Antarctic region. "So you get ozone depletion not just over Antarctica but over where we live," noted the researcher.Ozone depletion by volcanic eruption is a recent phenomenon, said Robock. "Elevated levels of chlorine in the stratosphere only started appearing within the last couple of decades due to human activity," he said.The scientist added that as the use of chlorofluorocarbons and other human emissions are regulated by International agreement, ozone depletion should disappear in a few decades."Researchers are already documenting that the amount of ozone-destroying compounds in the atmosphere has stopped rising, " said Robock.

Ozone Holes

January 16, 2002

https://www.sciencedaily.com/releases/2002/01/020116072538.htm

Greenhouse Emissions Growth Slowed Over Past Decade

A new NASA-funded study shows that the rate of growth of greenhouse gas emissions has slowed since its peak in 1980, due in part to international cooperation that led to reduced chlorofluorocarbon use, slower growth of methane, and a steady rate of carbon dioxide emissions.

Researchers have shown that global warming in recent decades has probably been caused by carbon dioxide (CO2), and other greenhouse gases including chlorofluorocarbons (CFCs), methane, tropospheric ozone, and black carbon (soot) particles. Overall, growth of emissions has slowed over the past 20 years, with the CFC phase-out being the most important factor, according to the study. "The decrease is due in large part to cooperative international actions of the Montreal Protocol for the phase-out of ozone depleting gases," said Dr. James Hansen of NASA's Goddard Institute for Space Studies, New York. "But it is also due in part to slower growth of methane and carbon dioxide, for reasons that aren't well understood and need more study." The findings appeared in the December 18 issue of the Proceedings of the National Academy of Sciences. Hansen co-authored the paper with Makiko Sato of Columbia University, New York. The warming effect of methane is about half as large as that of CO2, and when methane increases it also causes a rise in tropospheric ozone levels. Tropospheric ozone is a principal ingredient in "smog," which is harmful to human health and reduces agricultural productivity. The rate of methane growth has slowed during the past decade, and it may be possible to halt its growth entirely and eventually reduce atmospheric amounts, Hansen and Sato suggest. Another warming agent deserving special attention, according to the authors, is soot. Soot is a product of incomplete combustion. Diesel powered trucks and buses are primary sources of airborne soot in the United States. Even larger amounts of soot occur in developing countries. The study also suggests that reduction of methane emissions and soot could yield a major near term success story in the battle against global warming, thus providing time to work on technologies to reduce future carbon dioxide emissions. Currently, technologies are within reach to reduce other global air pollutants, like methane, in ways that are cheaper and faster than reducing CO2. Though reducing these climate-forcing agents is important, scientists caution that limiting CO2 will still be needed to slow global warming over the next 50 years. Hansen emphasizes that CO2 emissions are the single largest climate forcing, and warns that they need to be slowed soon and eventually curtailed more strongly to stabilize atmospheric conditions and stop global warming. Over the next few decades, Hansen said, it is important to limit emissions of forcing agents other than CO2, to buy time until CO2 emissions can be better managed. If fossil fuel use continues at today's rates for the next 50 years, and if growth of methane and air pollution is halted, the warming in 50 years will be about 1.3 degrees Fahrenheit (0.7 Celsius). That amount of warming is significant, according to Hansen, but it is less than half the warming in the "business-as-usual scenarios that yield the specter of imminent disaster." The climate warming projected in the Institute scenario is about half as large as in the typical scenario from the report of Intergovernmental Panel on Climate Change (IPCC). This is because the IPCC considers a large range of forcings and models. The warming in the GISS model is similar to the lowest of the IPCC results, despite the fact that the GISS model has a relatively high sensitivity to forcings. These agents can be categorized into three areas: greenhouse gases, other man-made (anthropogenic) forcings, and natural forcings. The greenhouse gases consist of carbon dioxide (CO2), methane (CH4), nitrous oxide (N20) and chlorofluorocarbons (CFCs). The other anthropogenic forcings consist of black carbon (soot, formed by incomplete combustion), reflective aerosols (tiny airborne particles that reflect sunlight back to space), soil or dust, land cover changes, and forced cloud changes. Natural forcings include changes of the sun's energy and changes of aerosols from volcanic eruptions. The total "forcing" of climate since 1850 includes a "positive" effect from all the greenhouse gases, which would have a warming effect. Of the other anthropogenic forcings, black carbon has also had a "positive" effect, whereas the other factors including: aerosols, soil and dust, cloud changes, and land cover alterations have had "negative" or cooling effects. Of the natural forcings, an increase of the Sun's brightness has caused a positive forcing, while variations of volcanic aerosols have caused both positive and negative forcings. Although the sum of all forcings coincidentally is similar to that for carbon dioxide alone, knowledge of each of the large forcings such as methane and black carbon (soot) is needed for development of effective policies. Climate forcings, or factors that promote warming, such as emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N20) and chlorofluorocarbons (CFCs) have increased in the world's atmosphere since the technology of the industrial revolution began pumping these into the atmosphere beginning in the 1800s. In the graph, climate forcings due to CO2 increases are depicted in light blue, CH4 in dark blue, N20 in yellow, and CFCs in red. In a new study, James Hansen of NASA's Goddard Institute for Space Studies and Makiko Sato of Columbia University found that the growth rate of climate forcings have slowed substantially from almost 5 Watts/meter2 (W/m2) per century to about 3 W/m2 since their peak in 1980. A watt is a unit of energy and a "watt per meter squared" is the amount of energy the forcing agents have over an area of one square meter. Typically, a forcing of 1Watt after 50 years of would yield a warming of 1.35ƒF (3/4ƒC) by 2050 in changing climate model simulations. The peak in the mid-1980s and drop in the late 1980s of CFCs is evident in the reduction of the red colored area on the graph toward the end of the 1980s. "The decrease is due in large part to cooperative international actions of the Montreal Protocol for the phase-out of ozone depleting gases," Hansen said. "But it is also due in part to slower growth of methane and carbon dioxide, for reasons that aren't well understood and need more study." Hansen and Sato report that emission trends need to be further reduced to approximately 2 W/m2 per century for the next 50 years to achieve a "moderate climate change scenario."

Ozone Holes

September 19, 2001

https://www.sciencedaily.com/releases/2001/09/010919073151.htm

NASA Confirms North Pole Ozone Hole Trigger

NASA researchers using 22 years of satellite-derived data have confirmed a theory that the strength of "long waves," bands of atmospheric energy that circle the earth, regulate the temperatures in the upper atmosphere of the Arctic, and play a role in controlling ozone losses in the stratosphere. These findings will also help scientists predict stratospheric ozone loss in the future.

These long waves affect the atmospheric circulation in the Arctic by strengthening it and warming temperatures, or weakening it and cooling temperatures. Colder temperatures cause polar clouds to form, which lead to chemical reactions that affect the chemical form of chlorine in the stratosphere. In certain chemical forms, chlorine can deplete the ozone layer. One theory is that greenhouse gases may be responsible for decreasing the number of long waves that enter the stratosphere, which then thins the ozone layer. Just as the weather at the Earth's surface varies a lot from one year to the next, so can the weather in the stratosphere. For instance, there were some years like 1984, in which it didn't get cold enough in the Arctic stratosphere for significant ozone loss to occur. "During that year, we saw stronger and more frequent waves around the world, that acted as the fuel to a heat engine in the Arctic, and kept the polar stratosphere from becoming cold enough for great ozone losses," said Paul Newman, lead author of the study and an atmospheric scientist at NASA's Goddard Space Flight Center, in Greenbelt, Md. "Other years, like 1997, weaker, and less frequent waves reduced the effectiveness of the Arctic heat engine and cooled the stratosphere, making conditions just right for ozone destruction," Newman said. The paper appears in the September 16 issue of Journal of Geophysical Research-Atmospheres. The temperature of the lower level of the stratosphere over the poles is also controlled by the change in seasons from winter to spring, and by gases such as ozone, water vapor and carbon dioxide. A long wave or planetary wave is like a band of energy, thousands of miles in length that flows eastward in the middle latitudes of the upper atmosphere, and circles the world. It resembles a series of ocean waves with ridges (the high points) and troughs (the low points). Typically, at any given time, there are between one and three of these waves looping around the Earth. These long waves move up from the lower atmosphere (troposphere) into the stratosphere, where they dissipate. When these waves break up in the upper atmosphere they produce a warming of the polar region. So, when more waves are present to break apart, the stratosphere becomes warmer. When fewer waves rise up and dissipate, the stratosphere cools, and the more ozone loss occurs. Weaker "long waves" over the course of the Northern Hemisphere's winter generate colder Arctic upper air temperatures during spring. By knowing the cause of colder temperatures, scientists can better predict what will happen to the ozone layer. The temperature of the polar lower stratosphere during March is the key in understanding polar ozone losses - and the temperature at that time is usually driven by the strength and duration of "planetary waves" spreading into the stratosphere. This discovery provides a key test of climate models that are used to predict polar ozone levels. "This then lends itself to adjusting climate models, and increasing their accuracy, which means scientists will have a better way to predict climate change in the future," Newman said. The stratosphere is an atmospheric layer about 6 to 30 miles above the Earth's surface where the ozone layer is found. The ozone layer prevents the sun's harmful ultra-violet radiation from reaching the Earth's surface. Ultra-violet radiation is a primary cause of skin cancer. Without upper-level ozone, life on Earth would be non-existent. The research used temperature measurements of the stratosphere from the Upper Atmospheric Research Satellite (UARS).

Ozone Holes

August 2, 2001

https://www.sciencedaily.com/releases/2001/08/010802080620.htm

Solar Storms Destroy Ozone, Study Reconfirms

A new study confirms a long-held theory that large solar storms rain electrically charged particles down on Earth's atmosphere and deplete the upper-level ozone for weeks to months thereafter. New evidence from NASA and NOAA satellites is helping scientists better understand how man and nature both play a role in ozone loss.

The study, appearing in the August 1 issue of Geophysical Research Letters, examined impacts of a series of huge solar explosions on the atmosphere in the Northern Hemisphere. A solar flare with an associated coronal mass ejection sent positively-charged protons streaming to Earth from July 14 to 16th, 2000. The bombardment of protons, called a solar proton event, was the third largest in the last 30 years. Solar storms consist of coronal mass ejections and solar flares. Coronal mass ejections are huge bubbles of gas ejected from the Sun and are often associated with these flares. Solar flares are explosions on the Sun that happen when energy stored in twisted magnetic fields (usually above sunspots) is suddenly released. When protons like these bombard the upper atmosphere, they break up molecules of gases like nitrogen and water vapor, and once freed, those atoms react with ozone molecules and reduce the layer. "A lot of impacts on ozone are very subtle and happen over long periods of time," said Charles Jackman, a researcher at NASA Goddard Space Flight Center's Laboratory for Atmospheres and lead author of the study. "But when these solar proton events occur you can see immediately a change in the atmosphere, so you have a clear cause and effect." The study's investigators used measurements from the Halogen Occultation Experiment (HALOE) instrument aboard the Upper Atmosphere Research Satellite (UARS) and the Solar Backscatter Ultraviolet (SBUV/2) instrument aboard the NOAA-14 satellite to obtain data on amounts of atmospheric gases like ozone and oxides of nitrogen in different layers of the atmosphere in the Northern Hemisphere. The investigators then compared readings before and during the event. When the sun's protons hit the atmosphere they break up molecules of nitrogen gas and water vapor. When nitrogen gas molecules split apart, they can create molecules, called nitrogen oxides, which can last several weeks to months depending on where they end up in the atmosphere. Once formed, the nitrogen oxides react quickly with ozone and reduce its amounts. When atmospheric winds blow them down into the middle stratosphere, they can stay there for months, and continue to keep ozone at a reduced level. Protons similarly affect water vapor molecules by breaking them up into forms where they react with ozone. However, these molecules, called hydrogen oxides, only last during the time period of the solar proton event. These short-term effects of hydrogen oxides can destroy up to 70 percent of the ozone in the middle mesosphere. At the same time, longer-term ozone loss caused by nitrogen oxides destroys a maximum of about nine percent of the ozone in the upper stratosphere. Only a few percent of total ozone is in the mesosphere and upper stratosphere with over 80 percent in the middle and lower stratosphere. "If you look at the total atmospheric column, from your head on up to the top of the atmosphere, this solar proton event depleted less than one percent of the total ozone in the Northern Hemisphere," Jackman said. While impacts to humans are minimal, the findings are important scientifically. "Solar proton events help us test our models," Jackman said. "This is an instance where we have a huge natural variance. You have to first be able to separate the natural effects on ozone, before you can tease out human-kind's impacts." Chlorine and bromine are major culprits in ozone decline. Most of the chlorine and bromine comes from human-produced compounds such as chlorofluorocarbons (CFCs) and halon gas. NASA's HALOE was launched on the UARS spacecraft September 15, 1991 as part of the Earth Science Enterprise Program. Its mission includes improvement of understanding stratospheric ozone depletion by measuring vertical profiles of ozone, hydrogen chloride, hydrogen fluoride, methane, water vapor, nitric oxide, nitrogen dioxide, aerosols, and temperature. The SBUV/2 instrument was launched aboard the NOAA-14 satellite on December 30, 1994 and its mission is to observe the ozone layer.

Ozone Holes

June 28, 2001

https://www.sciencedaily.com/releases/2001/06/010619074209.htm

Refrigerator Disposal Releases Ozone-Depleting Chemicals

Shredded foam insulation from junked refrigerators is releasing substantial amounts of ozone-depleting chlorofluorocarbons, or CFCs, into the earth's atmosphere — and the more finely shredded the foam, the faster the release, a Danish researcher reports.

The first study looking at how and how fast CFC gas releases from foam insulation used in older refrigerators is reported in the July 15 issue of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society. More than eight million refrigerators and freezers in the United States reach the end of their useful lives and are thrown away annually, generally ending up at a landfill where they are shredded to recover scrap metal. Shredding one discarded refrigerator can quickly release more than 100 grams of CFC-11 into the environment, reports Peter Kjeldsen, Ph.D., an associate professor at the Technical University of Denmark. All 500 grams of CFC gas in the insulation of each refrigerator — a total of nearly 4,000 tons of CFC emissions — can eventually seep from the appliances over the next 300 years, he said. "The future atmospheric concentrations of CFC-11, and their effect on the ozone layer, will mainly depend on the continued release from insulation foams," Kjeldsen said. Comparing their laboratory CFC-release rates to computer models, the researchers found that all CFC gas embedded in the energy-saving insulation is slowly, but surely, released after the foam is ripped apart. The smaller the size of the shredded foam, the faster the release, he noted. Some other countries, including Denmark, dispose of the foam before scrapping the refrigerator, which eliminates most CFC emissions, Kjeldsen said. Although CFCs were developed in the 1930s, the majority of the CFC emissions are coming from refrigerators made during the 1980s, when a new type of insulating foam featuring the material was used. The appliances normally last for around 20 years, Kjeldsen said. "Use of these results may help evaluate changes in the atmospheric concentrations of CFC-11 in the future," he said. "They add to the understanding of a very important source of CFCs." Chlorine contained in CFCs damages the earth's ozone layer, a thin shield of oxygen that protects the planet from ultraviolet radiation. A single chlorine atom — contained in CFCs and also found naturally — can destroy more than 100,000 ozone molecules, although ozone can be reformed over time by a chemical reaction stimulated by sunlight. The upper part of the atmosphere known as the stratosphere contains approximately 3 billion kilograms of ozone — enough to create a layer about an eighth of an inch thick that circles the globe. Depletion of the ozone layer leads to higher levels of a certain type of ultraviolet (UV) radiation reaching the earth's surface. Previous testing has shown that higher UV-B levels increase the risk of skin cancer, harm plant life, reduce the population of sea life and contribute to the increase of carbon dioxide and other greenhouse gases believed to be responsible for atmospheric warming, according to the U.S. Environmental Protection Agency. Because of the dangers of exhausting the ozone layer, more than 120 countries signed the 1987 "Montreal Protocol" to control CFC emissions. After 1995, when production of most CFCs stopped, they ceased being used in aerosol cans and in the coolant known as Freon™. New products, including refrigerators, use substitutes with similar properties. Additional amounts of CFC-11 can be found in air conditioners, insulation and some industrial appliances. A different type of CFC is used in the product marketed as Styrofoam™. The research cited above was partially funded by the Danish Technical Research Council. Peter Kjeldsen, Ph.D., is an associate professor in the department of environment and resources unit at the Technical University of Denmark in Lyngby, Denmark.

Ozone Holes

April 27, 2001

https://www.sciencedaily.com/releases/2001/04/010427071254.htm

Most-Serious Greenhouse Gas Is Increasing, International Study Finds

April 24, 2001 -- Scientists know that atmospheric concentrations of greenhouse gases such as carbon dioxide have risen sharply in recent years, but a study released today in Paris reports a surprising and dramatic increase in the most important greenhouse gas – water vapor – during the last half-century.

The buildup of other greenhouse gases (those usually linked with climate change) is directly attributable to human activity, and the study indicates the water vapor increase also can be traced in part to human influences, such as the buildup of atmospheric methane. However, other causes not directly related to humans must also be at work, said Philip Mote, a University of Washington research scientist who is one of seven lead authors on the report. "Half the increase in the stratosphere can be traced to human-induced increases in methane, which turns into water vapor at high altitudes, but the other half is a mystery," said Mote. "Part of the increase must have occurred as a result of changes in the tropical tropopause, a region about 10 miles above the equator, that acts as a valve that allows air into the stratosphere." Readings of water vapor increases 3 to 10 miles up are more ambiguous, Mote said. The international study, produced by 68 scientists in seven countries as part of the World Climate Research Programme, examined only the changes at higher altitudes, 3 to 30 miles above sea level. Although carbon dioxide has been relatively easy to monitor and increases have been observed since the 1950s, water vapor has proven much more difficult to monitor. The new effort for the first time was able to draw conclusions about the behavior of water vapor based on a large number of measurements during a long period of time. The report covered both the upper troposphere (3 to 10 miles high), where trends are harder to detect, and the stratosphere (10 to 30 miles high). "A wetter and colder stratosphere means more polar stratospheric clouds, which contribute to the seasonal appearance of the ozone hole," said James Holton, UW atmospheric sciences chairman and expert on stratospheric water vapor. "These trends, if they continue, would extend the period when we have to be concerned about rapid ozone depletion." Atmospheric heating happens when the Earth's atmosphere and surface absorb solar radiation, while cooling occurs when thermal infrared radiation escapes the atmosphere and goes into space. If certain key gases that absorb and emit infrared radiation, the most important being water vapor and carbon dioxide, were not present in the atmosphere, Earth's temperature would cool to minus 19 degrees celsius, or minus 2 degrees Fahrenheit. The global annual mean temperature is 14 degrees celsius. Key findings of the water vapor assessment are:* Ground-based, balloon, aircraft and satellite measurements show a global stratospheric water vapor increase of as much as 2 parts per million by volume in the last 45 years, a 75 percent jump.* Modelling studies by the University of Reading in England show that since 1980 the stratospheric water vapor increase has produced a surface temperature rise about half of that attributable to increased carbon dioxide alone.* Methane, which has been increasing in the atmosphere since the 1950s, could be contributing to the water vapor increase. Chemical conversion of methane to water vapor occurs in the stratosphere but can only account for at most half of the water vapor increase. A satellite record of relative humidity data for the upper troposphere shows a 2 percent increase during the last 20 years in the equatorial region. However, the uncertainty in this determination is too large to allow a clear conclusion as to whether this is part of a long-term trend. Among other things, the report recommends continuing to launch balloons monthly from Boulder, Colo., as a means to measure water vapor, a low-cost effort that nevertheless faces possible discontinuation. The balloon measurements, dating from 1981, are the only continuous record of water vapor. Holton said the report is significant because, by careful comparison, it largely has resolved contradictions in measurements among a number of instruments.

Ozone Holes

April 24, 2001

https://www.sciencedaily.com/releases/2001/04/010424073849.htm

Greenhouse Gases Main Reason For Quicker Northern Winter Warming

Greenhouse gases are the main reason why the northern hemisphere is warming quicker during winter-time months than the rest of the world, according to new computer climate model results by NASA scientists.

Climatologists consider volcanic aerosols, polar ozone depletion, solar radiation, and greenhouse gases to be important factors in climate warming. NASA scientists input all of these factors in a climate model and concluded that greenhouse gases are the primary factor driving warmer winter climates in North America, Europe and Asia over the last 30 years. They found that greenhouse gases, more than any of the other factors, increase the strength of the polar winds that regulate northern hemisphere climate in winter. Using a computer model that simulates climate through interactions of ocean and atmosphere, scientists input current and past levels of greenhouse gases such as carbon dioxide, methane, water vapor and nitrous oxide. They found that greenhouse gases such as those increase the strength of polar wind circulation around the North Pole. The polar winds play a large role in the wintertime climate of the northern hemisphere. The winds blow from high up in the stratosphere down to the troposphere and eventually the Earth’s surface. When they strengthen, as they do from increases in greenhouse gases, they blow stronger over the warm, moist oceans picking up and transporting warmer air to the continents. Thus, warm air from the Pacific Ocean warms western North America, and the Atlantic Ocean warmth is shared with Eurasia. When winds are stronger, winters are warmer because air picks up heat as the winds blow over the oceans. When winds become weak winters become colder.The findings by Drew Shindell, Gavin Schmidt, and other atmospheric scientists from NASA’s Goddard Institute for Space Studies and Columbia University, NY, appeared in the April 16 issue of the Journal of Geophysical Research – Atmospheres.Shindell noted that increases in greenhouse gases make the stronger polar winds last longer into the springtime and contribute to a warmer early spring climate in the northern hemisphere. The stronger wind circulation around the North Pole creates a large temperature difference between the pole and the mid-latitudes. Shindell noted that the Southern Hemisphere isn’t affected by increasing greenhouse gases the same way, because it’s colder and the polar wind circulation over the Antarctic is already very strong.“Surface temperatures in the Northern Hemisphere have warmed during winter months up to 9 degrees Fahrenheit over the last three decades, over 10 times more than the global annual average 0.7 degree Fahrenheit,” says Shindell. “Warmer winters will also include more wet weather in Europe and western North America, with parts of western Europe the worst hit by storms coming off the Atlantic.”Year-to-year changes in the polar winds are quite large, according to Shindell. But over the past 30 years, we have tended to see stronger winds and warming, indicative of continually increasing greenhouse gases.Shindell looked at volcanic activity from 1959 to 2000 and identified volcanically active and non-active years. The researchers concluded that because volcanic forcing is intermittent and decays rapidly, it seems unlikely to have contributed greatly to the long-term observed warming trend. Large volcanic eruptions such as Mount Pinatubo in 1991 inject aerosols into the atmosphere and have a global cooling effect during the years following an eruption. Also included in the model were the 11-year solar cycle and the effects of solar radiation on stratospheric ozone. Schmidt noted that long-term changes in solar irradiance have influenced the upper atmosphere. “However, it is unlikely that solar variability has been responsible for much of the observed trend in increasing the polar winds,” Schmidt said.Because the upper polar atmosphere becomes colder when ozone is depleted, the winds circling the pole are slightly enhanced. “However,” Shindell noted, “greenhouse gases have the biggest impact on the strengthening of the polar winds, and in turn, the warming of the northern hemisphere during winter months.”Shindell said that the warming trend would likely continue over the next 30 years as greenhouse gases continue to increase in the atmosphere.

Ozone Holes

April 18, 2001

https://www.sciencedaily.com/releases/2001/04/010418072442.htm

Wetter Upper Atmosphere May Delay Global Ozone Recovery

NASA research has shown that increasing water-vapor in the stratosphere, which results partially from greenhouse gases, may delay ozone recovery and increase the rate of climate change.

Drew Shindell, an atmospheric scientist from NASA's Goddard Institute for Space Studies (GISS) and Columbia University, NY, used the NASA/GISS global climate model with satellite and other remote sensing data to investigate long-term stratospheric cooling and ozone depletion. This study is the first to link greenhouse gases to increased ozone depletion over populated areas.Shindell found that he was able to best simulate the behavior of temperature and ozone in the upper atmosphere when he added water vapor data into the climate model."Climate models show cooler stratospheric temperatures happen when there is more water vapor present, and water vapor also leads to the breakdown of ozone molecules," Shindell said. According to satellite data, upper atmospheric temperatures around the world (20-35 miles high) have cooled between 5.4-10.8 degrees Fahrenheit over recent decades. The stratosphere is the typically dry layer of the atmosphere above the troposphere, where temperatures increase with height.According to Shindell there are two driving forces behind the change in stratospheric moisture. "Increased emissions of the greenhouse gas, methane, are transformed into water in the stratosphere," Shindell said, "accounting for about a third of the observed increase in moisture there."The second cause of change in the upper atmosphere is a greater transport of water from the lower atmosphere, which happens for several reasons. Warmer air holds more water vapor than colder air, so the amount of water vapor in the lower atmosphere increases as it is warmed by the greenhouse effect. Climate models also indicate that greenhouse gases such as carbon dioxide and methane may enhance the transport of water into the stratosphere. Though not fully understood, the increased transport of water vapor to the stratosphere seems likely to have been induced by human activities."Rising greenhouse gas emissions account for all or part of the water vapor increase," said Shindell, "which causes stratospheric ozone destruction."When more water vapor works its way into the stratosphere, the water molecules can be broken down, releasing reactive molecules that can destroy ozone. Shindell noted that his global climate model agrees with satellite observations of the world's stratospheric ozone levels when the water vapor factor is increased in the stratosphere over time. Shindell said, "If the trend of increasing stratospheric water vapor continues, it could increase future global warming and impede ozone stratospheric recovery."The impact on global warming comes about because both water vapor and ozone are greenhouse gases, which trap heat leaving the Earth. "When they change, the Earth's energy balance changes too, altering the surface climate," said Shindell. Increased water vapor in the stratosphere makes it warmer on the ground by trapping heat, while the ozone loss makes it colder on the ground. Water vapor has a much larger effect, so that overall the changes increase global warming. Shindell stressed that although ozone depletion cools the Earth's surface, repairing stratospheric ozone is very important to block harmful ultraviolet radiation, and other greenhouse gas emissions need to be reduced.Shindell used seven years of data from the Upper Atmosphere Research Satellite's (UARS) Halogen Occultation Experiment (HALOE) with ground based data to paint a complete picture of the upper atmosphere. He also used 14 years of lower stratospheric measurements that show large increases in water vapor. Though some studies conflict with lower stratospheric observations of water vapor trends, studies released since Shindell's paper was written, agree with the increases he used, and indicate that they have been taking place for more than four decades already.Shindell's paper, "Climate and Ozone Response to Increased Stratospheric Water Vapor," appears in the April 15th issue of Geophysical Research Letters.NASA's HALOE was launched on the UARS spacecraft September 12, 1991 as part of the Earth Science Enterprise Program. Its mission includes improvement of understanding stratospheric ozone depletion by analyzing vertical profiles of ozone, hydrogen chloride, hydrogen fluoride, methane, water vapor, nitric oxide, nitrogen dioxide, and aerosols.

Ozone Holes

March 19, 2001

https://www.sciencedaily.com/releases/2001/03/010316072904.htm

NASA Satellite Tracks Hazardous Smoke And Smog Partnership

New research sponsored by NASA may soon help scientists do a better job of tracking pollution plumes around the world and help provide people more advance warning of unhealthy air.

Researchers have discovered that smoke and smog move in different ways through the atmosphere. A series of unusual events several years ago created a blanket of pollution over the Indian Ocean. In the second half of 1997, smoke from Indonesian fires remained stagnant over Southeast Asia while smog, which is tropospheric, low-level ozone, spread more rapidly across the Indian Ocean toward India.This situation was exacerbated by El Nino, which had already increased the thickness of smog over the region. At the same time, additional smog from African fires streamed over the Indian Ocean and combined with the smog from Indonesia, creating an aerial canopy of pollutants. Researchers tracked the pollution using data from NASA's Earth Probe Total Ozone Mapping Spectrometer (TOMS) satellite instrument. "TOMS is the only satellite instrument that follows both smoke and smog, globally," said Anne Thompson, NASA Earth Scientist at Goddard Space Flight Center, Greenbelt, MD. "The extreme pollution generated during the Indonesian fires was the first time we saw smoke move more slowly and in different directions from where smog moved." Although TOMS has been observing the atmosphere since 1978, new air-quality technologies added in 1997 enabled scientists to see the divergence of smoke and smog for the first time.The different movement occurred because the pollutants were in different layers of the atmosphere. Heavier smoke particles stayed close to the region of the fires while smog moved more quickly and spread over a large area. "Typically, smog is seen coming from Africa because much more burning occurs there, but in 1997 the Indonesian plume was thicker due to the fires there," Thompson added.Between July and November 1997, the emissions from the Indonesian fires caused considerable air pollution throughout the Southeast Asian region, including Indonesia, Malaysia, and Singapore. Hazardous particles found in smoke caused air-quality and health problems throughout the region including asthma, upper respiratory infections, decreased lung function, and eye and skin irritation.Before the fires began in 1997, the El Nino and changing atmospheric patterns over the Indian Ocean, a pattern called the Indian Ocean Dipole, caused the ozone column to thicken, indicating that climatic factors play a major role. When scientists went back and looked at the 1980s El Nino events, they noticed the same behavior. "However, we can detect no trend in smog ozone during the 1980s in the tropics, even though burning may have increased," said Thompson. "In some regions of the tropics, rising ozone precedes the burning period and in other regions, ozone levels don't rise as much as we would expect during the local burning season. Clearly, factors other than biomass burning exert a strong influence on tropical tropospheric ozone."Since 1978, TOMS has eyed upper and lower level ozone in Earth's atmosphere. Since upper-level ozone in the stratosphere over the tropics is uniform, TOMS can subtract it out from its readings and calculate the smog in a "column" of atmosphere that stretches from the surface to the tropopause, more than 40,000 feet high.A paper titled "Tropospheric Ozone and Biomass Burning," by Goddard's Anne Thompson and researchers at the University of Maryland; Science Systems and Applications, Inc.; and Hokkaido University of Japan, explaining the divergence of the pollutants, appears in the March 16 issue of Science.This research was conducted by NASA's Earth Science Enterprise, a long-term research effort dedicated to studying how human-induced and natural change affects our global environment.

Ozone Holes

February 8, 2001

https://www.sciencedaily.com/releases/2001/02/010207074106.htm

Atmospheric Aerosols Impact On Smog Formation Being Reassessed

BERKELEY, CA — Computer models of air quality provide local governments with the scientific information they use to regulate air pollution emissions -- but these models are not always as accurate as regulators would like. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have been studying the photochemical characteristics of air pollution in southern California as part of an effort funded by the California Air Resources Board (CARB) to improve the reliability of air quality models. The Berkeley Lab team’s work has yielded new insights into how variability in the solar flux and the concentration of aerosols in the atmosphere affect the formation of smog.

Since the passage of the Clean Air Act in 1990, computer-based air quality models have been the basis of air quality regulation in the United States. Reducing uncertainties in model results has been a focus of much research. "One of the uncertainties," says Berkeley Lab’s Laurent Vuilleumier, "is how well the models represent the optical properties of the atmosphere and their effect on the photochemical reactions that form smog." CARB designated variability in sunlight and its effect on photochemistry as one of the areas needing improvement in current air quality models.Vuilleumier, a scientist in the Lab’s Environmental Energy Technologies Division, UC Berkeley’s Rob Harley, EETD’s Nancy Brown, and colleagues have been using data from CARB’s 1997 Southern California Ozone Study to gain a better understanding of the relationship between the amount of light entering the atmosphere and the rates of photochemical reactions that form ozone, a significant component of smog that influences the concentrations of other air pollutants."Ozone concentration is extremely sensitive to reactions that are driven by sunlight," explains Vuilleumier. "These photolysis reactions initiate the decomposition of chemical species such as nitrogen dioxide and formaldehyde by sunlight. The photolysis rates are variable because the amount of light reaching the lower atmosphere -- called the solar actinic flux -- is variable. Aerosols, particles in the atmosphere, can extinguish light through scattering and absorption, reducing the rate of certain smog-forming reactions in the lowest layers of the troposphere, while sometimes enhancing their rates in the higher layers."Vuilleumier, Harley, Brown and colleagues used the SCOS 97 measurements of solar ultraviolet irradiance, taken at two stations in Riverside and Mount Wilson, to compute the atmosphere’s total optical depth. As a measure of the transparency of the atmosphere to the penetration of sunlight, optical depth is very influential in determining solar flux. Using a mathematical method called principal component analysis, the researchers separated the factors affecting optical depth into components, and determined which components were most significant.The largest component, which the researchers attribute to the concentration of aerosols in the atmosphere, accounted for 91 percent of the variability in the data. The second component, the concentration of ozone, accounted for another eight percent of the observed variability."These results tell us that air quality models need to be modified to better account for the effects of aerosol and ozone concentration on smog formation," says Vuilleumier. "As a result of this work, we have prepared a report to CARB reviewing the mathematical methods used in the models to represent atmospheric optical properties and their effect on photochemical reactions, with suggestions on how to improve them. There are many other variables that affect the accuracy of these models, such as meteorological factors, chemistry and emissions inventories, and we hope to continue our studies of some of these for CARB."Air quality models typically used by CARB today include the Urban Airshed Model and the SARMAP (San Joaquin Valley Air Quality Study Regional Model Adaptation Project) Air Quality Model."Variability in Ultraviolet Total Optical Depth during the Southern California Ozone Study (SCOS97)," by Vuilleumier, Robert Harley, and Nancy Brown of Berkeley Lab, and James Slusser (Colorado State University), Donald Kolinski (University Corporation for Atmospheric Research) and David Bigelow (Colorado State) will be published in the February 2001 issue of Atmospheric Environment.Berkeley Lab is a U.S. Department of Energy laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

Ozone Holes

January 19, 2001

https://www.sciencedaily.com/releases/2001/01/010119080544.htm

Study: Sea Salt Seasons Chemical Brew That Destroys Arctic Ozone

WEST LAFAYETTE, Ind. — Sunlight, snow and sea salt are sometimes used to illustrate Nature at its best. But new scientific evidence shows that, when combined, these forces may provide a potent mixture for destroying ozone.

Purdue University researchers, working with researchers from the University of California, Irvine and Battelle, have found that two chemicals found in sea salt may serve as precursors to initiate a series of chemical events that destroy ozone in the Arctic troposphere, the lowest part of the atmosphere.The findings, published in the Jan. 19 issue of the scientific journal Science, describe the role that bromine and chlorine play in a complex series of chemical reactions that occur each spring when, after several months of darkness, sunlight interacts with the snow in the Arctic region.The study traces the source of those chemical precursors to the salty minerals found in sea water that is carried into the snowpack in the form of tiny salt particles by wind and waves."Bromine and chlorine have long been suspected as major players in this series of chemical events, but the source of these chemicals was unknown," says Paul Shepson, professor of atmospheric chemistry at Purdue. "Our findings indicate that this near-surface ozone depletion in the Arctic is a naturally occurring event."The findings may help scientists develop better models to simulate and predict long-term changes in the composition of the earth's atmosphere, Shepson says. "Because three-quarters of the earth's surface is covered by ocean, we've uncovered a process we need to understand much better in terms of our ability to model ozone in the atmosphere."Current models don't take these interactions into account because scientists are only beginning to recognize and document the role that snow and sea salt play in atmospheric chemistry. In 1986, scientists observed that, at polar sunrise, which occurs in March or April after several months of complete darkness, ozone in a thin layer of air over the Arctic ocean is completely removed. "This was a big surprise to us, and it indicated that our understanding of atmospheric ozone, and the factors that lead to its production and depletion, is poor," Shepson says.Since then, scientists have found evidence that a number of chemicals that lay dormant in the snow can interact with sunlight to produce chemical "pollutants" — such as nitric oxide, nitrogen dioxide, formaldehyde and bromine — that impact the composition of the atmosphere.Last year, Shepson and colleague Jan Bottenheim of Environment Canada led a research group to the Canadian Arctic to measure levels of bromine and chlorine in the snowpacks, and analyze how sunlight interacts with these chemicals during the polar sunrise.From a research site at the Canadian Forces base at Alert, Canada, the group measured levels of bromine and chlorine in the snow and air over a two-month period, beginning in early February. The bromine and chlorine measurements were conducted under the leadership of Chet Spicer of Battelle-Columbus, and Barbara Finlayson-Pitts of the University of California, Irvine.The measurements show that in mid-March, when the sun began to rise over the Arctic region, these elements increased in the air while decreasing in the snow.Because molecular bromine is short-lived in the atmosphere and can't be transported very far, Shepson and co-workers began looking for sources of bromine from the local environment. "Sea salt is the only source of bromine in the Arctic," he says.Bromine and chlorine also play a role in destroying ozone in the upper atmosphere over the Arctic and Antarctic, but in those cases the sources of bromine and chloride come primarily from human-derived pollutants, Shepson says.Though the study indicates that ozone-depletion is a naturally occurring process in the Arctic, the findings suggest that mixtures of snow and salt on roads in urban areas may also affect air quality, Shepson says."The ingredients from what we observe in the Arctic are sometimes present in high concentrations on the streets of urban areas during the winter months," says Shepson, an expert in chlorine chemistry. "I wouldn't want to make predictions, but there could be a variety of chemical interactions that occur in urban, road-salted environments that we need to understand." Shepson's studies at Purdue are funded by the National Science Foundation.

Ozone Holes

January 16, 2001

https://www.sciencedaily.com/releases/2001/01/010116075723.htm

Atmospheric Chemistry Key To Global And Local Air Pollution

Albuquerque, N.M. -- The chemical cycles in the troposphere along with pollutants of human and natural origin can alter the composition of the air and effect local, regional and global environmental quality, according to a Penn State researcher.

The troposphere -- the area of the Earth's atmosphere from the surface to ten miles above the surface where weather exists -- is also where pollution becomes a problem. In the atmosphere, a complex series of chemical reactions can alter some pollutants so that they rain out as aerosol particles or acid rain and clear the air. Other compounds remain in the air, changing, and changing again as other chemicals cause reactions."Pollution from megacities and biomass burning, including precursor gases to hydrogen oxides such as acetone and formaldehyde, lofted into the upper troposphere, can become the dominant hydrogen oxide source and result in efficient ozone production," says Dr. William Brune, professor of meteorology and head of Penn State's meteorology department. "These compounds can also be transported great distances before descent, possibly influencing the chemistry of remote regions."Ozone is complicated. In the stratosphere it serves to protect life from the detrimental effects of the sun's ultraviolet radiation. At ground level, it is a pollutant implicated in respiratory problems and eye irritation. Sunlight breaks ozone apart resulting in the creation of the very reactive hydroxyl radical which begins the process that removes some pollutants from the air. However, when hydroxyl radicals break down some compounds, they produce other hydrogen oxides, which react with other pollutants and form ozone."The hydroxyl radical drives atmospheric oxidation by reacting with chemicals emitted from Earth‚s surface, thus creating new chemicals that are more easily scavenged and removed by aerosols, clouds and rain," Brune told attendees today (Jan. 15) at the annual meeting of the American Meteorological Society in Albuquerque, N.M. "But in the oxidation process, hydroperoxyl radicals form and combined with the industrial pollutant nitric oxide produces ozone. The sun then breaks down this ozone, creating hydroxl radicals and starting the cycle all over again."Brune is part of ongoing studies to measure the amounts of hydroxyl radical and hydroperoxyl radical in the atmosphere over various areas of the globe during different times of the day. So far, using airplane-mounted equipment, they have tested air over the south Pacific near Hawaii, Fiji, Tahiti and Easter Island, over the North Atlantic flight corridor, and are preparing for flights over the western pacific from Hong Kong and Tokyo. Measures of hydroxyl and hydroperoxyl radicals reflect the outflow of air carrying pollutants off China and other industrialized nations. The study over the North Atlantic flight corridor assessed the contribution of air travel to this type of pollution. Brune has also tested air from ground towers in lower Michigan and Houston, Texas. To measure these radicals, special equipment samples the air and uses a laser to excite the hydroxyl radicals so that they fluoresce. The hydroxyl count is proportional to this fluorescence. The researchers count hydroperoxyl radicals by releasing nitrogen oxide that rapidly reacts with hydroperoxyl to form the hydroxyl radical. They then count the hydroxyl and subtract the hydroxyl that was there before the nitric oxide."The Michigan environment was dominated by trees that produce an organic compound called isoprene," says Brune. The hydroxyl radical reacts with isoprene to form a hydrocarbon oxide radical. Whether the next reaction produces or reduces hydrogen oxides depends on the amount of nitrogen oxide in the air. "Isoprene, a naturally occurring compound, in the presence of nitrogen oxide produced by power plants is very reactive and can create a lot of ozone," says Brune. "We want to test the understanding of the basic chemical reactions for isoprene." The complex nature of the chemistries of ozone, the hydroxyl radical and the hydroperoxyl radical is not always as simple as sunlight and human-produced pollution. Even naturally occurring organic compounds, like isoprene, under the right circumstances can produce unexpected results. Observations of hydrogen oxide levels, nitrogen oxide levels and other meteorological factors over areas as different as an urban city, a rural forest and the Pacific ocean shed light on the fundamental relationships among atmospheric oxidation, ozone production, nitrogen oxide and hydrogen oxides. "The major thrust of atmospheric research is tied into the Earth science," says Brune. "We look at things locally, then regionally and globally. It all comes back to affecting us locally."

Ozone Holes

December 15, 2000

https://www.sciencedaily.com/releases/2000/12/001215082423.htm

"Raining" Electrons Contribute To Ozone Destruction

First-time evidence shows electrons precipitating or 'raining' from Earth’s magnetosphere are destroying ozone in the upper atmosphere.

Scientists involved in the study of Solar-Atmospheric Coupling by Electrons (SOLACE) will report on this finding at the Fall American Geophysical Union (AGU) meeting in San Francisco, December 15-19, 2000. They have determined that this coupling can create a significant amount of nitrogen oxides highlighting a new aspect of natural ozone destruction. Billions of electrons spiral back and forth between Earth’s poles in the magnetosphere. The magnetosphere is an invisible region around Earth where its magnetic field controls the motions of charged particles (including electrons) in space. Even though the magnetosphere protects Earth from solar processes, the field itself can be disturbed. Fluctuations in solar wind, for example, can interfere with the magnetosphere and cause electrons to descend into the atmosphere. "It’s important that we know what events affect ozone in the stratosphere, and until now this effect on ozone hasn’t been considered important," said Linwood Callis, lead research scientist for this work at NASA Langley Research Center, Hampton, Va. Current models used to study ozone variations and climate change have not taken this solar-atmospheric coupling into account. Scientists determined that the degree of electron precipitation is directly related to the 11-year solar cycle. By excluding this cycle in models, interpretation of observed ozone changes could be misleading. Data models including electron precipitation are much more accurate than models that exclude the effects of electrons.

Ozone Holes

November 29, 2000

https://www.sciencedaily.com/releases/2000/11/001129075753.htm

Unprecedented Fire Season In Southern Africa Aids Air Quality, Climate Change Research

The fires that raged across southern Africa this August and September produced a thick "river of smoke" that observers compared with the aftermath of the Kuwaiti oil fires in 1991. NASA-supported studies currently underway on the event will contribute to improved air pollution policies in the region and a better understanding of its impact on climate change.

"Every year African biomass burning greatly exceeds the scale of the fires seen this year in the western United States," says Robert Swap of the University of Virginia, one of the organizers of the Southern African Regional Science Initiative (SAFARI 2000) field campaign. "But the southern African fire season we just observed may turn out to be an extreme one even by African standards. It was amazing how quickly this region went up in flames."The intensive SAFARI 2000 six-week field campaign was planned to coincide with the dry-season fires. The experiment included observations from NASA's Terra and Landsat 7 spacecraft, research aircraft including NASA's ER-2 high-altitude jet, and several ground stations. Over 200 scientists from around the world participated in the campaign, which ended Sept. 25. This year the southern African fire season peaked in late August and early September. The region is subject to some of the highest levels of biomass burning in the world. SAFARI 2000 planners tracked the changing location of fires with daily satellite maps provided by researchers at NASA's Goddard Space Flight Center (Greenbelt, Md.). The heaviest burning was in western Zambia, southern Angola, northern Namibia, and northern Botswana. Some of the blazes had fire fronts 20 miles long that lasted for days. The thick haze layer from these fires produced between Aug. 23 and Sept. 7 was heavier than campaign participants had seen in previous field studies in the Amazon Basin and during the Kuwati oil fires. "We observed a river of smoke that moved from northwest to southeast over the subcontinent, causing heavy haze and reduced visibility over Botswana and South Africa for about ten days in early September," says SAFARI 2000 organizer Harold Annegarn of the University of the Witwatersrand, Johannesburg.According to veteran pilot Ken Broda, who flew NASA's ER-2 above the haze layer, "this was probably the worst in-flight visibility I've seen anywhere, even during the oil fires following the Persian Gulf war. From the ER-2's altitude of 60,000 feet, where normal visibility can stretch 60 miles, I couldn't clearly see the city of Johannesburg until I was directly overhead." With instruments on the ground, in the air, and in space, scientists were able to sample the chemistry and measure the thickness of the smoke plumes, map the movements of the haze layer, and investigate how the smoke and fine aerosol particles affect clouds. "For the first time we were able to track this annual haze from its source and determine what happens to the aerosols in the haze," says Annegarn. "The measurements we have now of carbon transport in the haze, both as gases and particles, will add important pieces to balancing global carbon budgets." Studies by research aircraft flying inside the pall of haze revealed several surprises. Aircraft encountered puzzling layers of extremely clean air sandwiched between polluted layers. "The pollution in the region is often very stratified with height in the atmosphere," says Peter Hobbs of the University of Washington, principal investigator for the experiments onboard the university's Convair-580 aircraft. "Regions of heavy pollution were separated by a very thin - just a few hundred feet deep - layer of almost pristine air." The haze aerosols sampled were also more heat-absorbing than expected, which means the haze layer may have a significant warming influence on the region's atmosphere. "The aerosol in the region was surprisingly absorbing," says Hobbs. "Such aerosols may well add to the greenhouse warming effect, particularly in the mid-troposphere. Most aerosols are thought to offset that warming by scattering incoming solar radiation back into space." The thick haze also contained high levels of ozone, a component of smog, that frequently reached levels similar to those found during air pollution alerts in major U.S. cities. Making the first balloon-borne measurements of ozone during the height of a southern African burning season, NASA Goddard scientist Anne Thompson found that the impact of the haze may be greater on climate change than on human health. "Ozone levels in U.S. urban centers may be more unhealthy at the ground, but the ozone profiles we took in Zambia show that much of the ozone here is in the middle and upper troposphere where ozone's 'badness' is its effect as a greenhouse gas," says Thompson. New air quality data collected during the campaign will also help governments in the region develop future environmental policies. Annegarn and other South African scientists are working to distinguish the industrial sources of air pollution from natural sources such as emissions from vegetation and soils."With the SAFARI 2000 data we now have the first comprehensive measurements of aerosols from the major industrial sources in southern Africa," said Annegarn. "Together with the detailed chemical analyses of these sources gathered during the campaign, we can now evaluate the relative importance of industrial emissions in the region's air pollution, which will contribute to the development of both national and regional air quality management policies." U.S. participation in the SAFARI 2000 campaign was sponsored by NASA's Earth Observing System (EOS) project, a suite of spacecraft and interdisciplinary science investigations dedicated to advancing our knowledge of global change. EOS is managed by Goddard Space Flight Center for NASA's Earth Science Enterprise. A key objective of this year's campaign was to acquire measurements for validating new data products from NASA's Terra spacecraft. More information on the SAFARI 2000 project is available at: http://safari.gecp.virginia.edu/

Ozone Holes

November 3, 2000

https://www.sciencedaily.com/releases/2000/11/001103071346.htm

UC Irvine Study Determines Levels Of Ozone-Depleting Gases Emitted By Rice Paddies Into Atmosphere

Irvine, Calif. -- A UC Irvine study has determined that the world's rice paddies emit a small but significant amount of methyl halide gases that contribute to stratospheric ozone depletion, suggesting that agricultural sources also play a role in this atmospheric phenomena.

In the first field study to understand methyl halide gas emissions from agricultural crops during an entire season, a team led by UCI Chancellor Ralph J. Cicerone, an internationally recognized researcher on stratospheric ozone depletion, and graduate student researcher Kelly R. Redeker has estimated the amounts of these gases contributed by rice farming. These findings will be published in the Nov. 3 issue of Science.Methyl halide compounds include methyl chloride, methyl bromide and methyl iodide, which become reactive agents when released into the atmosphere. Bromine and chlorine, two products of these reactions, are directly involved with stratospheric ozone depletion. Iodine is believed to affect tropospheric ozone, a common air pollutant. The 1987 Montreal Protocol has restricted products such as chlorofluorocarbons (CFCs), halons and methyl bromides that contribute chlorine and bromine to the atmosphere and are believed to be primarily man-made. The goal of these restrictions is to reduce the human contribution to halogens in the atmosphere."As the major industrial sources of these halides increasingly are being regulated, it's now even more important to uncover their natural sources," Cicerone said. "We only know where half of the methyl chloride and two-thirds of the methyl bromide are coming from. This study is significant because it gives direct evidence that some of the unknown sources of these halides could very well be plant sources."Methyl bromide used as a soil fumigant, for example, is being banned because of concern over its effect on stratospheric ozone. Yet agricultural plants also release it into the air. So to understand the potential benefits of a ban on methyl bromide, we must learn about the sizes of natural sources."After monitoring the methyl halide gases emitted from a rice paddy in Maxwell, Calif., over two planting seasons in 1998 and 1999, the UCI team calculated that worldwide rice farming contributes 1 percent of the methyl bromide and 5 percent of the methyl iodide to atmospheric totals."We were surprised at the scale of methyl iodide emissions," Redeker said. "We're still not sure how important a role methyl iodide plays in atmospheric chemistry, but we have found that it lingers over the fields during its maximum emission stage, meaning that it may have some impact on local environmental issues."They also noted that unplanted flood fields emit as much methyl chloride as planted flooded fields, suggesting that global wetlands may be a notable natural source and worth further study.The UCI team also found that the rate of methyl halide emissions is not constant, varying with stage of plant development in the growing season, soil halide amount and soil organic content. Emissions of methyl bromide, for instance, increased during tilling and appeared to peak during the reproductive stage of rice growth. Methyl iodide appears to have maximum emissions during the vegetative phase. However, methyl chloride counts were unaffected by stages of rice growth.In addition, Cicerone took air samples from rice paddies in Texas and Japan in 1997 and 1998 during selected phases of plant growth and harvest, and in comparing data with the Maxwell study, found that halide and organic differences in various soils influence emission amounts.The UCI team followed its Maxwell research by monitoring a planting season in rice paddies near Houston. In addition, Redeker is involved with greenhouse studies on the UCI campus, growing rice in different soil and water conditions to study the impact on methyl halide emissions. Eventually, Cicerone and his team would like to expand this research to rice-growing regions in Southeast Asia and to other plants.Studying rice farming is important in understanding the natural sources of ozone-depleting gases. Rice is the world's largest crop and is the primary source of food for billions. As the human population grows, so will the need for increased rice cultivation. Currently, it is estimated that rice paddies cover 1 percent of the Earth's landmass. Rice paddies also are a significant contributor of methane, a greenhouse gas, which forms in soil pores and is passed into the air through the rice plant.The study was conducted by researchers from UCI's departments of Earth System Science and Chemistry. Assisting Cicerone and Redeker were associate researchers Stanley Tyler and Nun-Yii Wang and graduate student researchers Jason C. Low and Andrew M. McMillan. Research funding came from the National Science Foundation and the U.S. Department of Agriculture.

Ozone Holes

September 8, 2000

https://www.sciencedaily.com/releases/2000/09/000908070144.htm

Largest-Ever Ozone Hole Observed Over Antarctica

A NASA spectrometer has detected an Antarctic ozone "hole" (what scientists call an "ozone depletion area") that is three times larger than the entire land mass of the United States - the largest such area ever observed.

The "hole" expanded to a record size of approximately 11 million square miles (28.3 million square kilometers) on Sept. 3, 2000. The previous record was approximately 10.5 million square miles (27.2 million square km) on Sept. 19, 1998. The ozone hole's size currently has stabilized, but the low levels in its interior continue to fall. The lowest readings in the ozone hole are typically observed in late September or early October each year. "These observations reinforce concerns about the frailty of Earth's ozone layer. Although production of ozone-destroying gases has been curtailed under international agreements, concentrations of the gases in the stratosphere are only now reaching their peak. Due to their long persistence in the atmosphere, it will be many decades before the ozone hole is no longer an annual occurrence," said Dr. Michael J. Kurylo, manager of the Upper Atmosphere Research Program, NASA Headquarters, Washington, DC. Ozone molecules, made up of three atoms of oxygen, comprise a thin layer of the atmosphere that absorbs harmful ultraviolet radiation from the Sun. Most atmospheric ozone is found between approximately six miles (9.5 km) and 18 miles (29 km) above the Earth's surface.Scientists continuing to investigate this enormous hole are somewhat surprised by its size. The reasons behind the dimensions involve both early-spring conditions, and an extremely intense Antarctic vortex. The Antarctic vortex is an upper-altitude stratospheric air current that sweeps around the Antarctic continent, confining the Antarctic ozone hole."Variations in the size of the ozone hole and of ozone depletion accompanying it from one year to the next are not unexpected," said Dr. Jack Kaye, Office of Earth Sciences Research Director, NASA Headquarters. "At this point we can only wait to see how the ozone hole will evolve in the coming few months and see how the year's hole compares in all respects to those of previous years.""Discoveries like these demonstrate the value of our long-term commitment to providing key observations to the scientific community," said Dr. Ghassem Asrar, Associate Administrator for NASA's Office of Earth Sciences at Headquarters. "We will soon launch QuickTOMS and Aura, two spacecraft that will continue to gather these important data."The measurements released today were obtained using the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASA's Earth Probe (TOMS-EP) satellite. NASA instruments have been measuring Antarctic ozone levels since the early 1970s. Since the discovery of the ozone "hole" in 1985, TOMS has been a key instrument for monitoring ozone levels over the Earth.TOMS ozone data and pictures are available on the Internet at: TOMS-EP and other ozone-measurement programs are important parts of a global environmental effort of NASA's Earth Science enterprise, a long-term research program designed to study Earth's land, oceans, atmosphere, ice and life as a total integrated system.

Ozone Holes

August 30, 2000

https://www.sciencedaily.com/releases/2000/08/000830073152.htm

New View On The Culprits Of Climate Change

Since climate change affects everyone on Earth, scientists have been trying to pinpoint its causes. For many years, researchers agreed that climate change was triggered by what they called "greenhouse gases," with carbon dioxide (CO2) from burning of fossil fuels such as coal, oil, and gas, playing the biggest role. However, new research suggests fossil fuel burning may not be as important in the mechanics of climate change as previously thought.

NASA funded research by Dr. James Hansen of the Goddard Institute for Space Studies, New York, NY, and his colleagues, suggests that climate change in recent decades has been mainly caused by air pollution containing non-CO2 greenhouse gases, particularly tropospheric ozone, methane, chlorofluorocarbons (CFCs), and black carbon (soot) particles. Since 1975, global surface temperatures have increased by about 0.9 degrees Fahrenheit, a trend that has taken global temperatures to their highest level in the past millennium. "Our estimates of global climate forcings, or factors that promote warming, indicate that it is the processes producing non-CO2 greenhouse gases that have been more significant in climate change," Hansen said. "The good news is that the growth rate of non-CO2 greenhouse gases has declined in the past decade, and if sources of methane and tropospheric ozone were reduced in the future, further changes in climate due to these gases in the next 50 years could be near zero," Hansen explained. "If these reductions were coupled with a reduction in both particles of black carbon and CO2 gas emissions, this could lead to a decline in the rate of climate change." Black carbon particles are generated by burning coal and diesel fuel and cause a semi-direct reduction of cloud cover. This reduction in cloud cover is an important factor in Earth's radiation balance, because clouds reflect 40 percent to 90 percent of the Sun's radiation depending on their type and thickness. Black carbon emission is not an essential element of energy production and it can be reduced or eliminated with improved technology. Hansen's research looked at trends in various greenhouse gases and noted that the growth rate of CO2 in the atmosphere doubled between 1950 and 1970, but leveled off from the late 1970s to the late 1990s. The other critical piece of information this research is based on, in addition to greenhouse gas levels, is observed heat storage, or warmer ocean temperatures, over the last century. Heat storage in the ocean provides a consistency check on climate change. The ocean is the only place that energy forms an imbalance. In this case a warming can accumulate, and global ocean data reveals that ocean heat content has increased between the mid-1950s and the mid-1990s. Hansen's paper, "Global Warming in the 21st Century an Alternate Scenario," will appear in the August 29th version of the Proceedings of the National Academy of Sciences. More information on the paper can be found at: NASA's Office of Earth Sciences, Headquarters, Washington, DC, sponsor research that studies how human-induced and natural changes affect our global environment. For more information about the Earth Sciences Enterprise, please see:

Ozone Holes

August 22, 2000

https://www.sciencedaily.com/releases/2000/08/000816073609.htm

Effects Of Ozone Pollution Threaten Agricultural Production On Long Island, NY, Says Cornell Plant Pathologist

For at least the past two summers, high amounts of ground-level ozone – a pollutant commonly called "smog" – have seriously retarded the growth of ozone-sensitive white clover in agricultural areas of Long Island, N.Y., according to a plant pathologist at Cornell University’s Horticultural Research and Extension Center in Riverhead, N.Y.

The effects of the pollutant on the clover appear to be a warning of a wider threat. "We need to pay attention to the amount of ground-level or ambient ozone," says Margaret McGrath, Cornell plant pathologist at the station. "There used to be a lot of spinach grown on Long Island. Not anymore. Spinach is very sensitive to ozone, which causes spotting on leaves and making them unmarketable. Acute injury routinely occurs on other Long Island crops, including grapes, pumpkins, watermelons and tomatoes. It’s difficult to assess the impact on yield and injury to the plant’s photosynthetic tissue. That’s why scientists are developing and using indicator systems such as white clover." McGrath is presenting her research in a poster, "Impact on White Clover of Ambient Ozone at Long Island, New York," on Aug. 15 and 16 at the annual meeting of the American Phytopathological Society at the Hyatt Regency Hotel in New Orleans. Most ozone occurs in the stratosphere and is called "good ozone" because it provides a shield against the harmful effects of the sun’s ultraviolet light. Ozone pollution occurs when abnormally high concentrations of the gas accumulate near the ground, the result of the reaction of sunlight with man-made precursor chemicals, including nitrogen oxides and volatile organic compounds. The gas enters leaves through tiny openings called stomata. McGrath says that environmental, biological and cultural factors – such as irrigation – promote the stomatal openings and increases the risk of ozone injury to plants. She also says that ozone causes deleterious effects on plant photosynthesis, as well as the rate of plant production, flowering and yield. While the processes are not well understood, ozone also can influence the incidence of pathogens and pests. In addition to its effect on plant shoots, ozone is known to hurt carbon flow to the root and, consequently, reduce root growth. Studying the response of cloned ozone-sensitive and ozone-tolerant white clover plants, McGrath found that ground-ozone levels were greater than 80 parts per billion (ppb) for 121 hours in 1998, and 184 hours in 1999. The highest ozone levels were reached on June 26, 1998, when concentrations peaked at 129 ppb, and on June 7, 1999 when they reached 123 ppb. In the 1998 research, the ozone-sensitive and ozone-tolerant white clover plants grew at a similar rate though the spring until just before the start of summer. After that the researchers noticed the ozone-sensitive clover experienced a 24 percent reduction in the growth rate through late summer. The researchers correlated the clover’s stunted growth with the increased ground-level ozone. In 1999, the ground-level ozone reduced the growth of the sensitive clover by 27 percent throughout the Long Island summer. "On hot summer days, the air just hangs over the island. Combine that with the intense ultraviolet rays and the greater New York City pollutants in the air, and you have a recipe for a lot of high ozone days," says McGrath. "These results document that ozone is high enough to greatly reduce growth and yield of sensitive plants on Long Island, where important agriculture in New York is located."

Ozone Holes

August 15, 2000

https://www.sciencedaily.com/releases/2000/08/000811063645.htm

A Simple Model For The Formation Of Ice Clouds

Atmospheric ice clouds strongly affect both the chemistry and the radiant properties of the Earth. However, the formation of ice particles in the atmosphere through homogeneous ice nucleation is not fully understood. This is due to the fact that ice forms in aqueous aerosol droplets which can be composed of a great variety of constituents. Scientists from the Federal Institute of Technology Zurich (Switzerland) and the Max Planck Institute for Chemistry in Mainz (Germany) show that the formation of atmospheric ice particles can be described by a general thermodynamic model (Nature, 10 August 2000).

Using laboratory data on a large number of solutes, they show that ice nucleation is independent of the nature of the solute. The only important parameters required to describe ice particle formation are temperature and relative humidity. They further show that their model is in good agreement with recent observation of ice clouds. These results should help to overcome one of the main weaknesses of numerical models of the atmosphere, the formulation of cloud processes. Important applications range from issues like denitrification and future ozone depletion in the Arctic polar stratosphere to the aerosol indirect effect due to homogeneously formed ice clouds in climate studies. The simplicity of the formulation makes it suitable not only for small scale process studies of individual clouds but also for global scale three-dimensional models.The results of this study also have important implications in other areas of research. For example, the scientists show that solutes and applied pressure have a very similar effect on ice nucleation which might be important for the understanding of the physics of supercooled water and aqueous solutions. The results also challenge classical theories of nucleation of crystals from liquid solutions. Finally, the new ice nucleation model may also have implications in the field of cryobiology, because it sets a inferior limit to the freeze resistance of cells in plants and animals at low temperatures.

Ozone Holes

August 1, 2000

https://www.sciencedaily.com/releases/2000/08/000801075407.htm

Ozone Found To Have Direct Effect On Genes Linked With Plants’ Aging

University Park, Pa. — Penn State research has shown, for the first time, that ozone, a major smog constituent, has a direct effect on the genes associated with the aging process in plants.

Dr. Jennifer Miller, who produced the finding as part of her doctoral thesis, says, "Plant scientists have long known that ozone accelerates the process through which the leaves of a plant age, eventually die and drop. However, our work provides the first evidence that the genetic program that controls the aging process is directly affected by ozone exposure."The findings may help other researchers find a way to bolster plants’ resistance to ozone, a critical component of smog, which causes an estimated $3 billion in agricultural losses in the United States each year, she notes.Miller detailed her findings in her doctoral dissertation, "Scenescence-Associated Gene Expression in Ozone-Stressed Arabidopsis Leaves," which she defended in June. She is currently an assistant professor of biology at Southwestern College, Winfield, Kansas. Some of her findings were also detailed earlier in a paper, Senescence-Associated Gene Expression during Ozone-Induced Leaf Senescence in Arabidopsis, published in the journal Plant Physiology. Co-authors are Dr. Richard N. Arteca, professor of horticulture and plant physiology, and Dr. Eva J. Pell, the Steimer professor of agricultural sciences, who was Miller’s thesis adviser.Miller conducted her experiments with Arabidopsis, a plant with a short 6 to 8 week life span and a small gene pool that is often used in plant studies. In one experiment, she grew the plants from seed and exposed one group of plants to low levels of ozone for six hours a day while leaving another group untreated."The ozone treatment was higher than ambient levels but not high enough to cause visible signs of damage immediately following the exposure. Ozone concentrations in polluted areas can reach the levels used in these experiments but not usually for six hours straight," Miller explains.The plants received ozone exposure a few days after they had produced a fifth leaf. As the leaves aged, yellowing was accelerated and growth retarded on the ozone-treated plants. Examining the plants’ aging-related genes every other day during the 14 day treatment period showed that some of them were turned on earlier in the ozone-stressed plants indicating a direct effect on the plants’ genetic program.In another experiment, Miller used mutant plants that were unable to perceive ethylene produced by the plant. Ethylene production has long been thought to be an important cue that signals the timing of aging. However, even in the plants in which ethylene perception was disrupted, ozone treatment produced early aging and early activation of some aging genes."Although we don’t know exactly what all of the aging-related genes do, we now know that ethylene production is not the primary signal for gene expression," Miller says.She proposes that oxidative products, the same free radicals that are thought to influence produce aging in people, also may be a possible aging cue for plants. She says, as others have shown, it may be possible to enhance ozone resistance in plants simply by selecting plant varieties with higher levels of anti-oxidants.The research was supported by grants from the Environmental Protection Agency and the U.S. Department of Agriculture.

Ozone Holes

July 4, 2000

https://www.sciencedaily.com/releases/2000/07/000703091336.htm

Carbon Dioxide Could Replace Global-Warming Refrigerant

WEST LAFAYETTE, Ind. – Researchers are making progress in perfecting automotive and portable air-conditioning systems that use environmentally friendly carbon dioxide as a refrigerant instead of conventional, synthetic global-warming and ozone-depleting chemicals.

It was the refrigerant of choice during the early 20th century but was later replaced with manmade chemicals. Now carbon dioxide may be on the verge of a comeback, thanks to technological advances that include the manufacture of extremely thin yet strong aluminum tubing.Engineers will discuss their most recent findings from July 25 to 28, during the Gustav Lorentzen Conference on Natural Working Fluids, one of three international air-conditioning and refrigeration conferences to be held concurrently at Purdue University. Unlike the two other conferences, the biannual Gustav Lorentzen Conference, which is being held for the first time in the United States, focuses on natural refrigerants that are thought to be less harmful to the environment than synthetic chemical compounds."The Gustav Lorentzen Conference focuses on substances like carbon dioxide, ammonia, hydrocarbons, air and water, which are all naturally occurring in the biosphere," says James Braun, an associate professor of mechanical engineering at Purdue who heads the organizing committee for all three conferences. "Most of the existing refrigerants are manmade."Purdue engineers will present several papers detailing new findings about carbon dioxide as a refrigerant, including:• Creation of the first computer model that accurately simulates the performance of carbon-dioxide-based air conditioners. The model could be used by engineers to design air conditioners that use carbon dioxide as a refrigerant. A paper about the model will be presented on July 26 during a special session sponsored by the U.S. Army in which researchers from several universities will present new findings.• The design of a portable carbon-dioxide-based air conditioner that works as well as conventional military "environmental control units." Thousands of the units, which now use environmentally harmful refrigerants, are currently in operation. The carbon dioxide unit was designed using the new computer model. A prototype has been built by Purdue engineers and is being tested.• The development of a mathematical "correlation," a tool that will enable engineers to design heat exchangers – the radiator-like devices that release heat to the environment after it has been absorbed during cooling – for future carbon dioxide-based systems. The mathematical correlation developed at Purdue, which will be published in a popular engineering handbook, enables engineers to determine how large a heat exchanger needs to be to provide cooling for a given area.• The development of a new method enabling engineers to predict the effects of lubricating oils on the changing pressure inside carbon dioxide-based air conditioners. Understanding the drop in pressure caused by the oil, which mixes with the refrigerant and lubricates the compressor, is vital to predicting how well an air conditioner will perform.Although carbon dioxide is a global-warming gas, conventional refrigerants called hydrofluorocarbons cause about 1,400 times more global warming than the same quantity of carbon dioxide. Meanwhile, the tiny quantities of carbon dioxide that would be released from air conditioners would be insignificant, compared to the huge amounts produced from burning fossil fuels for energy and transportation, says Eckhard Groll, an associate professor of mechanical engineering at Purdue.Carbon dioxide is promising for systems that must be small and light-weight, such as automotive or portable air conditioners. Various factors, including the high operating pressure required for carbon-dioxide systems, enable the refrigerant to flow through small-diameter tubing, which allows engineers to design more compact air conditioners. More stringent environmental regulations now require that refrigerants removed during the maintenance and repair of air conditioners be captured with special equipment, instead of being released into the atmosphere as they have been in the past. The new "recovery" equipment is expensive and will require more training to operate, important considerations for the U.S. Army and Air Force, which together use about 40,000 portable field air conditioners. The units, which could be likened to large residential window-unit air conditioners, are hauled into the field for a variety of purposes, such as cooling troops and electronic equipment."For every unit they buy, they will need to buy a recovery unit," Groll says. "That's a significant cost because the recovery unit is almost as expensive as the original unit. Another problem is training. It can be done, but it's much more difficult than using carbon dioxide, where you could just open a valve and release it to the atmosphere."The recovery requirement would not apply to refrigerants made from natural gases, such as carbon dioxide, because they are environmentally benign, says Groll, who estimates that carbon dioxide systems probably will take another five to 10 years to perfect.Carbon dioxide was the refrigerant of choice a century ago, but it was later replaced by synthetic chemicals."It was actually very heavily used as a refrigerant in human-occupied spaces, such as theaters and restaurants, and it did a great job," says Groll, who is chair of the Gustav Lorentzen Conference.But one drawback to carbon dioxide systems is that they must be operated at high pressures, up to five times as high as commonly seen in current technology. The need to operate at high pressure posed certain engineering challenges and required the use of heavy steel tubing.During the 1930s, carbon dioxide was replaced by synthetic refrigerants, called chlorofluorocarbons, or CFCs, which worked well in low-pressure systems. But scientists later discovered that those refrigerants were damaging the Earth's stratospheric ozone layer, which filters dangerous ultraviolet radiation. CFCs have since been replaced by hydrofluorocarbons, which are not hazardous to the ozone layer but still cause global warming.However, recent advances in manufacturing and other technologies are making carbon dioxide practical again. Extremely thin yet strong aluminum tubing can now be manufactured, replacing the heavy steel tubing.Carbon dioxide offers no advantages for large air conditioners, which do not have space restrictions and can use wide-diameter tubes capable of carrying enough of the conventional refrigerants to provide proper cooling capacity. But another natural refrigerant, ammonia, is being considered for commercial refrigeration applications, such as grocery store display cases, Groll says.Engineering those systems is complicated by the fact that ammonia is toxic, requiring a more elaborate design in which the ammonia refrigerant is isolated from human-occupied spaces. The first ammonia systems are currently being tested in Europe, and results will be presented during the Gustav Lorentzen Conference, Groll says.Groll's work is funded by the U.S. Army, Air Force and the American Society of Heating, Refrigerating and Air-Conditioning Engineers, as well as the Air Conditioning and Refrigeration Technology Institute.

Ozone Holes

May 26, 2000

https://www.sciencedaily.com/releases/2000/05/000526071102.htm

Arctic Ozone May Not Recover As Early As Predicted

The ozone layer that protects life on Earth may not be recovering from the damage it has suffered over the Arctic region as quickly as scientists previously thought, according to a paper published in the May 26 issue of the journal Science. Specifics of the research also will be presented at the annual meeting of the American Geophysical Union in Washington, DC, on May 31.

More polar stratospheric clouds than anticipated are forming high above the North Pole, causing additional ozone loss in the sky over the Arctic, according to Dr. Azadeh Tabazadeh, lead author of the paper and a scientist at NASA's Ames Research Center in California's Silicon Valley. The stratosphere comprises Earth's atmosphere from about 9 to 25 miles (about 15 to 40 kilometers) altitude and includes the ozone layer. "Polar stratospheric clouds provide a 'double-whammy' to stratospheric ozone. They provide the surfaces which convert benign forms of chlorine into reactive, ozone-destroying forms, and they remove nitrogen compounds that act to moderate the destructive impact of chlorine," said Dr. Phil DeCola, Atmospheric Chemistry Program Manager at NASA Headquarters, Washington, DC. "The Arctic has become colder and more humid, conditions that promote formation of more polar stratospheric clouds that take part in polar ozone destruction. The main conclusion of our study is that if this trend continues, Arctic clouds will remain longer in the stratosphere in the future," Tabazadeh said. "An ozone hole forms every spring over the Antarctic in the Southern Hemisphere which is colder than the Arctic," said Tabazadeh. "The Arctic has been getting colder and is becoming more like the Antarctic; this could lead to more dramatic ozone loss in the future over the Northern Hemisphere, where many people live." Researchers used data from NASA's Upper Atmosphere Research Satellite to analyze cloud data from both the north and south polar regions for the study. "What we found from the satellite was that polar stratospheric clouds currently last twice as long in the Antarctic as compared to the Arctic," Tabazadeh said. "However, our calculations show that by 2010 the Arctic may become more 'Antarctic-like' if Arctic temperatures drop further by about 37 to 39 degrees Fahrenheit (about 3 to 4 degrees Celsius)," she said. When Arctic polar stratospheric clouds last longer, they can precipitate, removing nitrogen from the upper atmosphere, which increases the opportunity for chlorine compounds to destroy ozone more efficiently. The polar stratospheric clouds involved in the reactions contain nitric acid and water, according to researchers who discovered these clouds in 1986. "Data from the Microwave Limb Sounder on UARS have provided the first opportunity to observe nitric acid throughout the Arctic and the Antarctic over a period of many years," said Michelle Santee, a scientist at NASA's Jet Propulsion Laboratory, Pasadena, CA, who is a co-author of the Science paper. "The continued presence of nitric acid in the Arctic winter -- which is not the case in the Antarctic -- helps to moderate ozone loss by reducing the amount of reactive chlorine, but this could change in the future," she added. More than a decade ago, scientists determined that human-made chlorine and bromine compounds cause most ozone depletion. Manufacturers made the chlorine compounds, chloroflourocarbons or "CFCs," for use as refrigerants, aerosol sprays, solvents and foam-blowing agents. Fire fighters used bromine-containing halogens to put out fires. Manufacture of CFCs ceased in 1996 in signatory countries under the terms of the Montreal Protocol and its amendments. The Montreal Protocol bans CFC emissions. As a result, the chlorine concentration in the upper atmosphere is already starting to decline, according to Tabazadeh. "Scientists used to believe that as chlorine levels decline in the upper atmosphere, the ozone layer should slowly start to recover. However, greenhouse gas emissions, which provide warming at the Earth's surface, lead to cooling in the upper atmosphere. This cooling promotes formation of the kind of polar stratospheric clouds that contribute to ozone loss," she added. "Several recent studies, including this one, show that ozone recovery is more complex and will take longer than originally thought," she explained. This research was funded by the Office of Earth Sciences, NASA Headquarters, Washington, DC.

Ozone Holes

April 25, 2000

https://www.sciencedaily.com/releases/2000/04/000424173354.htm

NCAR Scientists Fly Into Arctic Circle, Lured By Spring Ozone Highs

BOULDER -- Every other Sunday a former military transport plane, packedwith scientists and specialized instruments, flies out of Coloradotoward the brutal cold of the Arctic Circle to scrutinize an annualspringtime rise in lower-atmosphere ozone levels. The researchers aremeasuring for the first time an array of chemicals that could shedlight on ozone production, atmospheric cleansing, and pollutiontransport in the northern latitudes. The National Center forAtmospheric Research (NCAR) leads the February-May mission. NCAR'sprimary sponsor, the National Science Foundation, is funding theexperiment.

As people use more fossil fuels, ozone plumes form in polluted citiesand drift around the world, and background levels continue to rise inthe lower atmosphere. Scientists are worried that an overburdenedatmosphere may lose its ability to adequately cleanse itself. Thepeculiar chemistry of the Arctic spring is key to understanding ozoneand pollution processes across the northern latitudes."Ozone is produced and destroyed all of the time, but if the balancegets too skewed, we may end up with more pollution than we cantolerate," says NCAR's Elliot Atlas, chief scientist for theexperiment.The NSF-owned C-130 aircraft flies 1,400 land miles to Churchill,Manitoba, on the Hudson Bay. Many more flight miles are added as theplane rises and falls to measure chemical compounds at variousaltitudes along the way.Churchill is a tourist spot for viewing white whales in the summerand polar bears in the fall. But to scientists working there in thefrigid spring, what's most striking are the cold, the blizzards, thesevere beauty--and the lack of an airplane hangar. Churchill'saircraft facilities are a runway and fuel. Through nighttime lows of-30 degree Celsius (-22 degree Fahrenheit), the plane sits outside,full of sensitive instruments that are ruined if they freeze. Insidethe cabin, heaters running on jet fuel fight the cold; outside,electric block heaters warm the engines. Staff take turns staying upall night to tend heaters and instruments.From Churchill the team sometimes flies another 1,400 miles to Thule,Greenland, and then on to Alert, the last settlement on the northerntip of the last piece of North America--Ellesmere Island. At leastThule has a hangar."Sometimes I wonder how we got into this. A week seems like a monthup there," says Atlas, who helped design the experiment. "But thescientific questions are so important that it's worth the hardship."Ozone levels in the Arctic troposphere (lower eight kilometers, orfive miles, of the atmosphere) increase from 30-40 parts per billion(ppb) in winter to 50-60 ppb in the spring--about half theconcentration above Los Angeles on a bad day. Meanwhile, in thestratosphere above, the returning springtime sun triggers chemicalreactions that deplete ozone, creating a smaller, northern version ofthe Antarctic ozone hole.Why these springtime highs and lows? Scientists suspect that someozone sinks from the stratosphere into the troposphere, but how much?As springtime weather changes circulation patterns, ozone and ozone-producing compounds travel into the far north from the pollutedregions of northern and central Europe. To what extent does thisinflux speed up the chemical processes that accompany the return ofsunlight? Scientists believe measurements of 20 or so chemicalspecies throughout the troposphere will provide answers. Already theyhave found surprises in the levels of important compounds.To complicate matters more, at ground level scientists have foundozone-empty bands about 30 miles across. To explore these areas, theC-130 coasts 100 feet above Hudson and Baffin Bays and the ArcticOcean, sampling chemistry occurring over the ice and open leads. TheNCAR researchers and their colleagues hope to find the crucial datato explain why ozone builds up in the lower atmosphere even as itvanishes entirely from some surface areas.Back at NCAR the measurements are helping scientists to fine tunetheir atmospheric chemistry models to better understand the chemistryand dynamics of the Arctic's lower atmosphere as winter gives way tospring.Other participants in the experiment, called Tropospheric OzoneProduction about the Spring Equinox (TOPSE), include NASA's Goddardand Langley Research Centers; Dalhousie, Georgia Tech, Harvard,Rutgers, and York Universities; and the Universities of California(Berkeley and Irvine), Colorado, Maryland, New Hampshire, RhodeIsland, and Virginia. Also collaborating are colleagues atEnvironment Canada and Purdue University, who are conducting ground-based research in the high Arctic.NCAR is managed by the University Corporation for AtmosphericResearch, a consortium of more than 60 universities offering Ph.D.sin atmospheric and related sciences.-The End-Note to Editors: Reporters are invited to view the airplane andinterview the chief scientists when they are in Colorado. Pleasecontact Anatta (303-497-8604) to arrange a visit.

Ozone Holes

April 18, 2000

https://www.sciencedaily.com/releases/2000/04/000414075355.htm

UC Irvine Researchers Discover How Airborne Sea Salt Particles May Influence Air Pollution Levels

rvine, Calif., April 13, 2000 — UC Irvine researchers who study the chemistry of ocean/air interactions have discovered how airborne sea salt particles may be involved in helping to determine the levels of some greenhouse gases as well as air quality in coastal urban areas.

In collaboration with other molecular scientists, Barbara Finlayson-Pitts, a UCI professor of chemistry, and Donald Dabdub, a UCI assistant professor of mechanical and aerospace engineering, have been able to show that sea salt particles—a common ingredient of coastal and ocean air—undergo a previously unrecognized chemical reaction in daylight to release chlorine molecules, which can influence ozone levels in the lower atmosphere. Their findings appear in the April 14 issue of Science. In sunlight, these molecules decompose into highly reactive chlorine atoms. When these atoms are formed in the presence of pollutants emitted from fossil fuel energy sources such as oil, coal and gasoline, they may lead to the formation of ozone, which is recognized as an air pollutant. Because ozone has documented health effects at quite low levels, both state and federal authorities have established quality standards for this pollutant. "The ocean is two-thirds of the earth's surface, so to understand global climate issues and the chemistry of air pollution in coastal regions, you need to understand the role of sea salt particles," Finlayson-Pitts said. "Our study suggests that sea salt particles may be a factor that needs to be taken into account in assessing levels of greenhouse gases and air pollutants such as ozone in the air." In this study, UCI researchers observed the reaction of hydroxyl radicals (equivalent to water, H2O, with a hydrogen atom removed) with tiny particles composed of water and sodium chloride—the basis of sea salts. The hydroxyl radical is always present in air. The researchers found unique chemical reactions on the surface of the sea salt particles rather than inside the particles, as had been previously observed. Until now, it was believed that a reaction between hydroxyl and sea salt required that the hydroxyl radical be absorbed into the liquid particle before reacting. It also was believed that chlorine would not be formed unless the particles were acidic. Neither of these two activities was observed in this study. The discovery of hydroxyl reactions on the surface of sea salt particles further suggests that the creation of atmospheric chlorine through sea salt interaction may be greater than previously realized. "This finding implies that this unique chemistry occurring on sea salt particle surfaces is yet another way of getting chlorine into the air," Finlayson-Pitts said. "Because they're so highly reactive, these chlorine atoms are important in the understanding of the formation and the fate of a number of trace gases vital to global climate issues." In continuing this research, Dabdub will introduce this information on sea salt chlorine creation into a complex computer modeling program that analyzes and predicts the air quality of the South Coast Air Basin of California—a highly populated coastal area that records some of the highest levels of air pollution in the United States—to see its impact on levels of ozone and other pollutants. Participating in this study with Finlayson-Pitts and Dabdub are Eladio Knipping of UCI's Department of Mechanical and Aerospace Engineering; Matthew Lakin, Krishna Foster, R. Benny Gerber and Douglas Tobias of UCI's Department of Chemistry, and Pavel Jungwirth of the J. Heyrovsky Institute of Physical Chemistry, Academy of Science in the Czech Republic. The study was funded by the U.S. Department of Energy, the National Science Foundation, the North Atlantic Treaty Organization (NATO) and the UCI Council on Research, Computing and Library Resources.

Ozone Holes