Laboratory for Atmospheres 2003 Technical Highlights: Appendix A1. Press Releases in 2003

January 6, 2003 - RELEASE: 03-04

NASA BEGINS NEW YEAR WITH INTERNATIONAL ARCTIC OZONE STUDY

NASA researchers, and more than 350 scientists from the United States, European Union, Canada, Iceland, Japan, Norway, Poland, Russia and Switzerland, are working together this winter to measure ozone and other atmospheric gases. The scientists will use aircraft, large and small balloons, ground-based instruments and satellites.

The Arctic campaign runs from Jan. 8 through Feb. 6, 2003. Flights of large balloons will augment the aircraft campaign, extending the measurement period to late March 2003.

This second SAGE III Ozone Loss and Validation Experiment (SOLVE II) campaign will be conducted in close collaboration with the European Commission. It is sponsored by the VINTERSOL (Validation of International Satellites & Study of Ozone Loss) campaign. (SAGE III stands for the third Stratospheric Aerosol & Gas Experiment.) SOLVE takes place in Kiruna, Sweden, the site of the first winter (1999-2000) international effort (SOLVE I).

NASA's SAGE III satellite instrument is being used to quantitatively assess ozone loss in the higher latitudes. SAGE III was launched onboard a Russian Meteor-3M spacecraft on December 10, 2001. The validation of the SAGE III observations is a principal goal of SOLVE II. SOLVE II is sponsored by NASA's Earth Science Enterprise, dedicated to better understanding and protecting our home planet.

"The primary goals of the joint SOLVE II-VINTERSOL campaign are to further understanding of ozone loss processes in the Arctic, and provide coincident observations between the airborne and SAGE III measurements. This comparison will enable the satellite scientists to critically and quantitatively assess the in-space performance of their instruments to measure profiles of ozone, aerosols, and water vapor over the Earth," said Michael Kurylo, SOLVE II co- Program Scientist at NASA Headquarters, Washington.

Ozone studies are important, because 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.

During the campaign of 1999-2000, record ozone losses of 70 percent were observed at altitudes around 18 kilometers (11miles), and a great deal was learned about the processes leading to the rapid ozone loss in the Arctic. The SOLVE II campaign will add to that body of knowledge.

During the coming winter, scientists in SOLVE II-VINTERSOL will work toward verifying the accuracy of measurements from current Earth observing satellites. The in situ and remote sensing measurements taken aboard these aircraft will provide a unique data set for comparison with the SAGE III instruments and other satellite instruments. Teams from the Centre National d'Etudes Spatiales (France's National Center for Space Studies) and NASA will launch research balloons carrying payloads weighing up to several hundred pounds from Kiruna. A network of over 30 stations of ground-based instruments will take atmospheric readings over a wide area to show how the chemical composition of Arctic stratosphere evolves through the whole winter.

VINTERSOL is a pan-European campaign involving researchers supported by the European Commission and national research agencies.


April 24, 2003 - RELEASE: 03-146

HURRICANE WINDS CARRIED OCEAN SALT & PLANKTON FAR INLAND

Researchers found surprising evidence of sea salt and frozen plankton in high, cold, cirrus clouds, the remnants of Hurricane Nora, over the U.S. plains states. Although the 1997 hurricane was a strong eastern Pacific storm, her high ice-crystal clouds extended many miles inland, carrying ocean phenomena deep into the U.S. heartland.

Kenneth Sassen of the University of Utah, Salt Lake City, and University of Alaska Fairbanks; W. Patrick Arnott of the Desert Research Institute (DRI) in Reno, Nev.; and David O. Starr of NASA's Goddard Space Flight Center, Greenbelt, Md., co-authored a paper about Hurricane Nora's far-reaching effects. The paper was published in the April 1, 2003, issue of the American Meteorological Society's Journal of Atmospheric Sciences.

Scientists were surprised to find what appeared to be frozen plankton in some cirrus crystals collected by research aircraft over Oklahoma, far from the Pacific Ocean. This was the first time examples of microscopic marine life, like plankton, were seen as "nuclei" of ice crystals in the cirrus clouds of a hurricane.

Nora formed off the Panama coast, strengthened as it traveled up the Baja Peninsula, and the hurricane crossed into California in September 1997. Over the western U.S., Nora deposited a stream of high cirrus, ice crystal, clouds that created spectacular optical effects, such as arcs and halos, above a broad region including Utah and Oklahoma. That stream of cirrus clouds enabled researchers to analyze growth of ice crystals from different nuclei.

Different nuclei, like sulfate particles, sea salt and desert dust, affect ice-crystal growth and shape. Torn from the sea surface by strong hurricane winds, sea salt and other particles from evaporated sea spray are carried to the cold upper troposphere in storm updrafts, where the drops freeze and become ice crystals. Plankton, a microscopic organism, is also likely present in the sea spray and is similarly lofted to high levels.

"Understanding how ice crystals grow and what determines their shapes is important in understanding how they interact with sunlight and infrared energy," Starr noted. "These interactions are important processes in the global climate system. They are also critical to sensing cloud properties from space, where NASA uses measurements of the reflected solar radiation to infer cloud physical properties, such as ice-crystal size," he said.

Data were gathered using ground-based remote sensors at the Facility for Atmospheric Remote Sensing in Salt Lake City and at the Clouds and Radiation Testbed in northern Oklahoma. A research aircraft collected particle samples over Oklahoma. Observations from the Geostationary Operational Environmental Satellite 9 (West), launched by NASA and operated by the National Oceanic and Atmospheric Administration, were also used. DRI analyzed the ice crystals collected from Nora.

Scientists were using data generated through the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program. The ARM Program's purpose is obtaining field measurements and developing computer models of the atmosphere. Researchers hope to better understand the processes that control the transfer of solar and thermal infrared energy in the atmosphere, especially in clouds, and at the Earth's surface.

The ARM energy measurements also double-check data from the Moderate Imaging Spectroradiometer instrument aboard NASA's Terra and Aqua satellites. By ensuring the satellites are recording the same energy reflected and absorbed by clouds from Hurricane Nora as those provided by the ground data in this study, scientists hope to take fewer ground measurements in the future, and enable the satellites to provide the data.

The DOE ARM program, National Science Foundation, and NASA's Earth Science Enterprise funded this research. The 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, such as hurricanes, using the unique vantage point of space.


May 1, 2003 - RELEASE: 03-44

NASA DISCOVERS A SOGGY SECRET OF EL NIÑO

NASA-funded researchers have discovered El Niño's soggy secret. When scientists identified rain patterns in the Pacific Ocean, they discovered the secret of how El Niño moves rainfall around the globe during the life of these periodic climate events when waters warm in the eastern Pacific Ocean.

The results may help scientists improve rainfall forecasts around the globe during the life of an El Niño, and may also offer new insights into how an El Niño develops.

The findings were highlighted in a paper authored by Scott Curtis of the University of Maryland - Baltimore County, Baltimore, Md., and Bob Adler, of Goddard Space Flight Center, Greenbelt, Md. The study appeared in a recent issue of the American Geophysical Union's Journal of Geophysical Research.

In an effort to predict and understand the effects of El Niño, most scientists focus on seasonal changes in rainfall patterns, like where and when rain falls during winter. This study takes a different approach by first looking at the evolution of rainfall over the geographic area of the Pacific, which has the power to change the global winds and re-direct rainfall patterns around the world.

Curtis and Adler found a significant pattern of alternating rainfall for El Niño since 1979, with wetness in eastern China, dryness over Indonesia and wetness in the south Indian Ocean and Australia.

They noted that this pattern swings eastward as the El Niño weakens. As El Niño weakens, rainfall patterns alternate from one area to another. In the eastern Pacific, there is wetness on the Equator, dryness off the coast of Mexico, and wetness off the coast of California. The traditional view of El Niño based on seasonal rainfall patterns obscures these relationships.

El Niño events, like individual thunderstorms, differ in intensity, lifespan, rainfall, and other characteristics, making them difficult to quantify. So, Curtis and Adler had to set parameters to define El Niño based on rainfall that occurs in the equatorial Pacific. They looked at the periods before rainfall began, when the El Niño started, peaked, faded, and after it ended. They also identified areas around the globe that were consistently wet or dry during each El Niño evolution stage.

Curtis and Adler utilized global rainfall datasets developed from satellites and rain gauges from all over the world, which are part of the Global Precipitation Climatology Project under the Global Energy and Water Cycle Experiment (GEWEX), a project heavily supported by NASA.

Data from the Tropical Rainfall Measuring Mission (TRMM) satellite, used in this study, will also help ensure the accuracy of satellites used by the National Oceanic and Atmospheric Administration (NOAA) and Department of Defense. TRMM is a joint NASA/Japanese Space Agency mission to study tropical rainfall and its implications for climate. Each day, the TRMM spacecraft observes the Earth's equatorial and tropical regions.

In the future this kind of study will help pinpoint where an El Niño will generate floods, droughts, and changes in rainfall around the globe. This information will be extremely useful once NASA's Global Precipitation Measurement mission, currently in formulation launches sometime after 2007.

This NASA funded work addresses a number of NASA's Earth Science Enterprise research strategies, including how variations in local weather, precipitation and water resources are related to global climate variation, in this case caused by El Niño. By recognizing global rainfall patterns associated with El Niño and by better understanding the impacts of El Niño, researchers may be able to better understand and predict these climate variations.


May 13, 2003 - RELEASE: 03-168

NASA FINDS SOOT HAS IMPACT ON GLOBAL CLIMATE

A team of researchers, led by NASA and Columbia University scientists, found airborne, microscopic, black-carbon (soot) particles are even more plentiful around the world, and contribute more to climate change, than was previously assumed by the Intergovernmental Panel of Climate Change (IPCC).

The researchers concluded if these soot particles are not reduced, at least as rapidly as light-colored pollutants, the world could warm more quickly.

The findings appear in the latest issue of the Proceedings of the National Academy of Sciences. It is authored by Makiko Sato, James Hansen and others from NASA's Goddard Institute for Space Studies (GISS) and Columbia University, New York; Oleg Dubovik, Brent Holben and Mian Chin of NASA's Goddard Space Flight Center, Greenbelt, Md.; and Tica Novakov, Lawrence Berkeley National Laboratory, Berkeley, Calif.

Sato, Hansen and colleagues used global atmospheric measurements taken by the Aerosol Robotic Network (AERONET). AERONET is a global network of more than 100 sun photometers that measure the amount of sunlight absorbed by aerosols (fine particles in the air) at wavelengths from ultraviolet to infrared. The scientists compared the AERONET data with Chin's global-aerosol computer model and GISS climate model, both of which included sources of soot aerosols consistent with the estimates of the IPCC.

The researchers found the amount of sunlight absorbed by soot was two-to-four times larger than previously assumed. This larger absorption is due in part to the way the tiny carbon particles are incorporated inside other larger particles: absorption is increased by light rays bouncing around inside the larger particle.

According to the researchers, the larger absorption is attributable also to previous underestimates of the amount of soot in the atmosphere. The net result is soot contributes about twice as much to warming the world as had been estimated by the IPCC.

Black carbon or soot is generated from traffic, industrial pollution, outdoor fires and household burning of coal and biomass fuels. Soot is a product of incomplete combustion, especially of diesel fuels, biofuels, coal and outdoor biomass burning. Emissions are large in areas where cooking and heating are done with wood, field residue, cow dung and coal, at a low temperature that does not allow for complete combustion. The resulting soot particles absorb sunlight, just as dark pavement becomes hotter than light pavement.Both soot and the light-colored tiny particles, most of which are sulfates, pose problems for air quality around the world. Efforts are beginning to reduce the sulfate aerosols to address air quality issues.

"There is a pitfall, however, in reducing sulfate emissions without simultaneously reducing black carbon emissions," Hansen said. Since soot is black, it absorbs heat and causes warming. Sulfate aerosols are white, reflect sunlight, and cause cooling. At present, the warming and cooling effects of the dark and light particles partially balance.

This research continues observations of global climate change. It 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.


May 27, 2003 - RELEASE: 03-172

COASTAL CITIES TURN UP THE HEAT ON RAINFALL

The old song, asking rain to "go away" and "come again another day," may get even older for people who live in large coastal cities, according to new NASA-funded research.

According to the study, urban heat islands, created from pavement and buildings in big coastal cities like Houston, cause warm air to rise and interact with sea breezes to create heavier and more frequent rainfall in and downwind of the cities. Analysis of Houston-area rain-gauge data, both prior to and since urbanization, also suggests there have been observed increases in rainfall as more heat islands were created.

The Houston-area study used data from the world's only space-based rain radar on NASA's Tropical Rainfall Measuring Mission (TRMM) satellite, and dense clusters of rain gauges.

Authors, J. Marshall Shepherd of NASA's Goddard Space Flight Center, Greenbelt, Md., and Steve Burian, a University of Arkansas, Fayetteville, Ark. researcher, believe the impact large coastal cities have on weather, and possibly climate, will become increasingly important as more people move into urban areas, with even greater concentrations in coastal zones. The paper is in the current American Meteorological Society and American Geophysical Union's journal, Earth Interactions.

A recent United Nations report estimates 60 percent of Earth's population will live in cities by 2025. Previous related studies have shown urban heat islands create heavier rainfall in and downwind of cities like Atlanta, St. Louis and Chicago. However, this is one of the first studies to provide evidence of such an effect around a U.S. coastal city. It is also the first to incorporate specific satellite-derived rainfall data for a coastal urban area.

Urban areas with high concentrations of buildings, roads and other artificial surfaces retain heat, which leads to warmer surrounding temperatures and creates heat islands. Rising warm air, promoted by the increased heat, may help produce clouds that result in more rainfall around cities. Buildings of different heights cause winds to converge, driving them upward, helping form clouds. The study shows the urban heat island/rain effect may be even more pronounced near coasts. In coastal cities like Houston, sea breezes also create rising air and clouds. The combination of urban converging winds and coastal sea breezes may enhance thunderstorm development.

"Recent publications have shown evidence of increased lightning activity over and downwind of Houston," Shepherd said. "Since lightning and rainfall are so closely related, we decided to use TRMM's Precipitation Radar, and a network of rain gauges, to see if urban-induced abnormal rainfall existed," he said.

Using data from 1998 to 2002, the researchers found mean rainfall rates, during the warm season, were 44 percent greater downwind of Houston than upwind, even though the regions share the same climate. They also found rainfall rates were 29 percent greater over the city than upwind. Rainfall rates indicate how hard it rains and can be an indicator of enhanced thunderstorm activity.

To rule out any effects from the coastline curvature near Houston on thunderstorm development, the researchers divided the entire Texas coast into seven zones extending 100 kilometers (62 miles) inland and including four or five major inlets or bays. Analysis of rainfall data in these zones showed abnormal rainfall only occurred over and downwind of Houston, which suggested effects from the urban landscape were significant. At the coastlines, TRMM satellite data were important, because they allowed researchers to assess rainfall data in areas where there were no gauges and records, like over the ocean.

A companion paper by the researchers, presented in March at a Geological Society of America meeting in Kansas City, Mo., stated urban areas also affect the timing of rainfall. Compared to upwind areas, there were nearly two times as many occurrences of rainfall from noon to midnight in the urban area. This finding has significant implications for flood control in Houston, Burian said.

NASA's Earth Science Enterprise, which supported this study, 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.


September 25, 2003 - RELEASE: 03-306

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: http://www.gsfc.nasa.gov/topstory/2003/0925ozonehole.html

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: http://www.noaa.gov/.


February 10, 2004 - RELEASE: 04-058 [Activity in 2003, release delayed to 2004]

NASA PREDICTS MORE TROPICAL RAIN IN A WARMER WORLD

As the tropical oceans continue to heat up, following a 20-year trend, warm rains in the tropics are likely to become more frequent, according to NASA scientists.

In a study by William Lau and Huey-Tzu Jenny Wu, of NASA's Goddard Space Flight Center, Greenbelt, Md., the authors offer early proof of a long-held theory that patterns of evaporation and precipitation, known as the water cycle, may accelerate in some areas due to warming temperatures. The research appears in the current issue of Geophysical Research Letters.

The study cites satellite observations showing the rate that warm rain depletes clouds of water is substantially higher than computer models predicted. This research may help increase the accuracy of models that forecast rainfall and climate. The rate water mass in a cloud rains out is the precipitation efficiency. According to the study, when it comes to light warm rains, as sea surface temperature increases, the precipitation efficiency substantially increases.

Computer climate models that predict rainfall have underestimated the efficiency of warm rain. Compared to actual observations from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite, computer models substantially underestimate the precipitation efficiency of light rain. The findings from this study will provide a range of possibilities for warm rain efficiency that will greatly increase a model's accuracy.

"We believe there is a scenario where in a warmer climate there will be more warm rain. And more warm rain will be associated with a more vigorous water cycle and extreme weather patterns," Lau said.

The process that creates warm rain begins when water droplets condense around airborne particles and clouds are created. The droplets collide, combine and grow to form raindrops. The raindrops grow large and heavy enough to fall out as warm rain. The study claims, for each degree rise in sea surface temperature, the rate a cloud loses its water to moderate-to- light warm rainfall over the tropical oceans increases by eight to 10 percent.

Cold rains are generally associated with heavy downpour. They are generated when strong updrafts carry bigger drops higher up into the atmosphere, where they freeze and grow. These drops are very large by the time they fall. Once updrafts take these large drops high enough, and freezing takes place, the process of rainfall is more dependent on the velocity of the updraft and less on sea surface temperatures. Since the process of condensation releases heat, warm rains heat the lower atmosphere. More warm rains are likely to make the air lighter and rise faster, creating updrafts producing more cold rain.

The study found warm rains account for approximately 31 percent of the total global rain amount and 72 percent of the total rain area over tropical oceans, implying warm rains play a crucial role in the overall water cycle. Light warm rains appear to occur much more frequently, and cover more area, than cold rains, even though they drop less water per shower. The total precipitation from all types of warm rains accounts for a substantial portion of the total rainfall.

In a warmer climate, it is possible there will be more warm rain and fewer clouds. If the amount of water entering into clouds stays constant and rainfall efficiency increases, then there will be less water in the clouds and more warm rains.

More study is needed to better understand the relationship between increased warm-rain precipitation efficiency and a rise in sea surface temperatures, and to determine how cold rain might be affected by an increase in warm rain and a decrease in cloud water amounts.

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.