Core Measurements at Summit, Greenland Environmental Observatory

This project involves long-term core measurements of the Arctic atmosphere, snow and other Earth system components at the Summit Greenland Environmental Observatory (GEOSummit). GEOSummit was the site of the GISP2 ice core, completed in 1993, and has been a site of atmospheric, snow and other geophysical measurements ever since. It is currently the only high-altitude site for atmospheric and related measurements in the Arctic. As global atmospheric temperatures rise, the Arctic environment is expected to undergo more rapid change in response to human influences than are other parts of the Earth system, in part due to feedbacks related to decreasing snowcover and sea-ice extent. Observed changes in Arctic temperature, atmospheric chemistry and atmospheric circulation are expected to have potentially broad but uncertain effects on Arctic systems. A number of processes that could amplify atmospheric change need consistent measurements and systematic study. For example, 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. 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. The project involves continuing and expanding the core suite of baseline measurements at GEOSummit for a five-year period, beginning in spring 2003. It also provides for the continued operation of GEOSummit as long-term site for year-round disciplinary and interdisciplinary measurements and research. Baseline measurements include meteorology, radiation, tropospheric chemistry, snow properties and snow chemistry. Some measurements will be made in cooperation with NOAA-CMDL, e.g. carbon cycle, chlorofluorocarbons, radiation, and ozone. GEOSummit staff will also carry out measurements initiated by individual investigators. 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. Understanding this change requires a quantitative understanding of the environmental controls (e.g., temperature, radiation, humidity, ozone concentration) on air-snow feedbacks, and the impact of these processes on the entire Arctic atmosphere. Broader impacts. The measurements at GEOSummit have wide applicability for detecting, understanding and modeling Arctic change, and are responsive to a number of community initiatives, including the World Meteorological Organization's Global Atmospheric Watch, SEARCH (A Study of Environmental Arctic Change) and other proposed initiatives. As such, this project provides the platform and baseline measurements for a wide number of scientists and individual research projects. There are at least three main broader impacts of the project. First and foremost, by definition an environmental observatory enhances infrastructure for research and education. Second GEOSummit serves as a vehicle to broadly disseminate scientific understanding of the Arctic system by making data and information widely available, both real time data and scientific understanding that is developed using those data. Third, education of the global community is an objective of the long-term measurements, using www-available data and educational materials. GEOSummit was chosen as the site for long-term measurements because it is in the remote free troposphere, and the chemical compositional changes observed in the long term reflect wide-scale change, uncomplicated by local biochemical processes, or by local changes in land use or emission patterns. The international science community has chosen Summit for multidisciplinary, multi-investigator studies, infrastructure is in place, and a number of Arctic researchers are collaborating there. The current project builds on the intermittent (but inadequate in terms of development of reliable models) atmospheric and surface-snow measurements that have been conducted over the past decade.