| Summary: | This 5-year project supports continuing and expanding the collection of long-term measurements of the Arctic atmosphere, snow and other Earth system components at the Summit Greenland Environmental Observatory (GEOSummit), located at an elevation of 3100 m on the Greenland ice sheet. A core suite of measurements has been collected at GEOSummit since 1993 and this project provides for the continued operation of GEOSummit as long-term site for year-round disciplinary and interdisciplinary measurements and research. The location provides a compliment to lower-elevation sites and a Northern Hemisphere analog to South Pole station. Measurements include baseline meteorology, radiation, tropospheric chemistry, snow properties and snow chemistry, some measurements in cooperation with NOAA-CMDL and measurements initiated by individual investigators. Measurements are aligned with the objectives of the World Meteorological Organization's Global Atmospheric Watch (GAW) program. The atmospheric gas-phase and aerosol species being studied are all either sensitive indicators of anthropogenic impacts on regional and global atmospheric change, or are important chemically coupled species whose concentrations may be strongly influenced by changes in the Arctic, including changes in snow/ice surface temperatures, ice/snow cover, and atmospheric circulation. Related chemical measurements in the snow provide the needed link to investigate feedbacks between Arctic climate change, air-snow exchange, and atmospheric composition. Recent evidence indicates that important atmospheric chemical constituents undergo temperature-dependent exchange with ice/snow, and that some species are photochemically transformed and/or produced within the sunlit surface snowpack. Understanding arctic environmental change requires a quantitative understanding of the environmental controls (e.g., temperature, radiation, humidity, ozone concentration) on air-snow feedbacks, as well as the impact of these processes on the entire Arctic atmosphere. Because changes in Arctic atmospheric circulation are cyclic over 4-5 year or longer times, long-duration measurements are needed to understand circulation and to place observed changes in a long-term perspective. Data and results will be shared via the National Snow and Ice Data Center data archive.
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