HR: 0800h
AN: GC51A-1051    [Abstracts]
TI: Ice Core Evidence of Recent Changes in Summer Melt Intensity of the Southern Greenland Ice Sheet
AU: * Das, S B
EM: sdas@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA 02543 United States
AU: Fahnestock, M A
AF: University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Durham, NH 03824 United States
AU: McConnell, J
AF: Desert Research Institute, Hydrologic Science Division, Reno, NV 89512 United States
AU: Hanna, E
AF: University of Sheffield, Department of Geology, Sheffield, UK S10 2TN United Kingdom
AU: Steffen, K
AF: University of Colorado, Cooperative Institute for Research In Environmental Sciences, Boulder, CO 80309 United States
AU: Box, J E
AF: Ohio State University, Byrd Polar Research Center, Columbus, OH 43210 United States
AB: Knowledge of past Greenland Ice Sheet surface melting extent and intensity, and associated climatic controls, is critical to understanding the current and future mass balance of the ice sheet. Surface melting is greatest along the margins of the Greenland Ice Sheet, but leaves no simple record of past patterns or intensity at low elevations. This makes it difficult to place ongoing changes in melt extent in a longer temporal context, and to determine the role of melting in the recent lowering of the surface at the margins of the ice sheet. At higher elevations melt leaves a clear record in the firn and ice, and the ice sheet stratigraphy can provide a unique record of past changes in surface melt extent. We present results of stratigraphic analyses of ten ice-cores from the southern Greenland Ice Sheet, spanning the past 25-100+ years. We use these results to investigate spatial and temporal changes in melt across the southern Greenland Ice Sheet for the past century. In general, the ice-core melt records show high interannual variability, as well as significant decadal variability. All the cores show a significant reduction in surface melt in 1992 and 1993 following the Mt. Pinatubo eruption. Many, but not all, cores also show an overall increase in melt extent towards the present. These stratigraphic records are compared to nearby automatic weather station records located on the ice sheet, longer-term records from coastal meteorological stations, as well as local surface temperature and meteorological model results based on ERA-40 reanalysis data from the European Center for Medium Range Weather Forecasts (ECMWF.) These records are combined to provide a more comprehensive view of the climatic controls of changes in surface melt over the southern Greenland Ice Sheet throughout the 20th century.
DE: 3344 Paleoclimatology
DE: 3349 Polar meteorology
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1600 GLOBAL CHANGE (New category)
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting