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Dec. 13, 2000

John Bluck

NASA Ames Research Center, Moffett Field, CA

(Phone: 650/604-5026 or 604-9000)


AGU Moscone Center press room, San Francisco, CA

(Phone: 415/905-1007, general AGU information during meetings)



Three to five times higher carbon emissions from annual burning in the Amazon went into the air in the early 1990s than was reported by similar, recent studies, according to a new NASA report slated for presentation Dec.16, at the American Geophysical Union (AGU) meeting at the Moscone Convention Center in San Francisco.

The scientific journal "Atmospheric Environment" will also print full results of the new NASA Amazon research. Principal author Christopher Potter of NASA Ames Research Center, Moffett Field, CA, will present the data at the AGU meeting at 9:30 a.m. PST, Saturday, Dec. 16, in room 122 Moscone Center. Almost 30 NASA Ames scientists will participate in a wide range of Earth science presentations, ranging from ozone depletion to the effects of dust in the atmosphere. A web page summarizes their reports at:

"Our study's results indicate carbon emission estimates from annual burning in the eight states of the Brazilian Legal Amazon in the early 1990s are three to five times higher than reported in similar, recent studies that implied the region tends towards a net-zero annual source of emissions from terrestrial carbon," Potter said. His study is part of the NASA-supported "Large Scale Biosphere-Atmosphere Experiment in Amazonia," an international research project led by Brazil. Co-authors are Vanessa Brooks Genovese and Matthew Bobo of NASA Ames, as well as Steven Klooster and Alicia Torregrosa, both of California State University Monterey Bay, Seaside, CA. The co-authors’ web pages contain more information at:

The AGU meeting will take place from Dec.15 - Dec.19, and several hundred scientists from government, universities and private industry plan to attend.

Later, Potter will talk about simulations of selected sites in Alaska's Denali National Park, which suggest that the past 50-year climate trends of warming temperatures may shift the local ecosystem from dominance by coniferous evergreen trees to a mixture of evergreens and deciduous, broad-leafed trees. He will make this presentation at 11:30 a.m., Dec. 16 in Moscone Center room 124.

Ames resident scientist John Livingston, a contractor with SRI International, Menlo Park, CA, will co-chair a "poster session" Dec.16, at 8:30 a.m. in Moscone's Hall D about a summer 2000 study of Saharan dust carried by winds to the Caribbean region. Researchers who studied Saharan airborne dust used a sunphotometer during 21 science airplane flights to measure how much sunlight penetrates smoke and other aerosols. In the dust study, as in other Earth science studies, once satellite data are calibrated with ground (or "ground truth") and airborne observations, scientists can use the satellite data to develop useful regional and global computer pictures of atmospheric or ground conditions.

Many NASA Ames scientists also contributed to more than 10 AGU presentations dealing with various aspects of ozone loss over the Arctic and Antarctic. The Earth's ozone layer protects life below from harmful ultraviolet radiation coming from the Sun that can lead to the formation of skin cancers. Scientists have observed unusually low levels of ozone over the Arctic during recent winters.

Ames scientist Hansjurg Jost is scheduled to make a presentation concerning the mixing of atmospheric gases related to ozone depletion. The talk will be Dec.16 at 9:40 a.m. in Moscone room 131. Jost will discuss results from data gathered by the NASA ER-2 high altitude aircraft that carried instruments which measured nitrous oxide, carbon dioxide, ozone and temperatures in regions of the Arctic stratosphere during the winter of 1999 -2000 to determine how these gases mix. The Arctic stratosphere is located from about 6 miles to 30 miles above Earth. Researchers found that various air masses have different gas mixes from their surroundings.

The exact makeup and temperature of air masses may be a factor in ozone destruction. Ozone-destroying clouds, or polar stratospheric clouds, are composed of water and nitric acid. Colder temperatures for a longer period of time cause "denitrification." This occurs when Arctic polar stratospheric clouds precipitate, removing nitrogen from the upper atmosphere. Denitrification increases the opportunity for chlorine compounds to destroy ozone more efficiently.

Cooling of the stratosphere will likely increase ozone loss during Arctic winters in coming decades, even as chlorine and bromine levels decrease as a result of the Montreal Protocol, according to scientists. The buildup of greenhouse gases, such as carbon dioxide, tends to trap more heat near Earth's surface, while at the same time colder than normal temperatures are experienced above, in the stratosphere, where ozone breakdown occurs, researchers said.

The ER-2 science flights took place as part of two international field experiments: NASA's SAGE III Ozone Loss and Validation Experiment (SOLVE) and the European Commission-sponsored Third European Stratospheric Experiment on Ozone (THESEO). More information about the AGU fall meeting is on the Internet at



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