Contact:  Barbara McGehan          FOR IMMEDIATE RELEASE
          NOAA PA                  April 23, 1997 
                                                       
          Allen  Kenitizer                        
          NASA PA       

A major international field mission to study stratospheric ozone over the Arctic during the spring to late summer time period will begin this month, involving researchers federal agencies, universities, and other nations. The study, dubbed POLARIS, (Photochemistry of Ozone Loss in the Arctic Region in Summer), will investigate the large natural seasonal decrease of ozone that occurs at this time of year in the Arctic.

Scientists from National Oceanic and Atmospheric Administration's Aeronomy Laboratory (AL) and Climate Monitoring and Diagnostics Laboratory (CMDL) in Boulder, Colo., will join other government and university researchers in loading scientific instruments aboard NASA's ER-2 high-altitude research aircraft. The scientists will participate in three four-week sessions running from April to September. The scientists will be measuring ozone, reactive nitrogen compounds, and other reactive and trace gases, looking at the photochemistry that destroys stratospheric ozone and the dynamics that influence ozone transport in the region. High-altitude balloon measurements will also be made. "This mission represents one of the most intensive campaigns ever conducted to investigate summertime ozone above the Arctic," said scientist James Elkins, a principal investigator from CMDL.

Ozone in the Arctic atmosphere has a pronounced annual cycle, declining by approximately 30% between the spring equinox and fall equinox. Although this decrease is associated with chemical reactions that occur naturally in the atmosphere, compounds such as chlorofluorocarbons (CFCs), and halons (fire retardants) released by human activities also play a role. Ozone in the upper atmosphere acts as a shield, protecting the earth from harmful ultraviolet rays. POLARIS will evaluate Arctic summer chemistry and atmospheric motions in sufficient detail that theoretical models of atmospheric ozone can be critically tested.

"This project will evaluate how gases that have natural sources, such as reactive nitrogen compounds, affect the Arctic ozone layer. This will help us to better understand the influence of human emissions of CFCs, halons, reactive nitrogen, and other gases," said co-project scientist David Fahey of NOAA's Aeronomy Laboratory, in Boulder, Colo. The POLARIS mission begins at the end of an Arctic winter season in which unusually large ozone losses were observed. Although not as severe as the "ozone hole" losses in the Antarctic springtime that are annually reported, scientists are looking more closely at ozone changes over the Arctic and in the northern latitudes. The mission is now scheduled to arrive in Alaska to begin sampling the polar region in time to observe these low ozone values in advance of the summer season.

POLARIS is expected to help scientists better understand the complex processes that are involved in ozone's seasonal cycle over the Arctic. Paul Newman from NASA's Goddard Space Flight Center (GSFC), the other project scientist, states that "the main scientific objective of this airborne campaign is to evaluate the natural summer decrease of summer ozone over a range of altitudes and latitudes in the northern hemisphere region, where most of the world's population is located."

After gathering the data, scientists will use photochemical models to analyze the measurements. Insights from the measurements and modeling activities will increase researchers' ability to explain observed and future changes of ozone abundances in the Arctic region. In addition, it will give researchers a better understanding of the effects of gases and particles emitted by subsonic and supersonic aircraft on the ozone layer in that region and on global climate. Model predictions indicate that changes in ozone from aircraft emissions are greatest in summer at mid-to high latitudes. Researchers will be looking at this connection between the photochemical responses and aircraft emissions.

POLARIS is a large, international field campaign coordinated by NASA under the Upper Atmospheric Research Program of the Office of Mission to Planet Earth, and the Atmospheric Effects of Aviation Project in the Office of Aeronautics. The ER-2 flights will be flown out of Fairbanks, Alaska, NASA's Ames Research Facility at Moffit Field, California, and Barber Field, Hawaii, where mid-latitude and subtropical measurements will be used as a basis for comparison.

For further information on the POLARIS mission including a complete list of participating institutions, consult the POLARIS home page at http://cloud1.arc.nasa.gov/polaris

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