C22B-08
The first long-term and continuous measurements of firn mass-balance and compaction on the Greenland Ice Sheet
Tuesday, 15 December 2015: 12:05
3007 (Moscone West)
Ian M Howat, OH St Univ-Earth Sciences, Columbus, OH, United States, Alberto Behar, NASA Jet Propulsion Laboratory, (deceased), Pasadena, CA, United States, Santiago de la Peña, Byrd Polar Research Center, Columbus, OH, United States, Stephen F Price, Los Alamos National Laboratory, Los Alamos, NM, United States, Darin Desilets, Organization Not Listed, Washington, DC, United States, James M Crowell, Arizona State University, Tempe, AZ, United States, Jekan Thangavelautham, Arizona State University, School of Earth and Space Exploration, Tempe, AZ, United States and Gary Womack, Quaesta Instruments, Tucson, AZ, United States
Abstract:
Direct, continuous measurements of ice sheet surface mass balance are lacking, particularly in the accumulation zone where the surface snow and firn varies in density. Nearly all of our knowledge of surface mass variability comes from snow pit and ice core stratigraphy, providing annual resolution with relatively large uncertainties that are inadequate for constraining meteorological models. Further, little information is available on how the density of the firn layer changes with time, hampering efforts to estimate mass change from altimetry measurements. Since the spring of 2012 we have obtained continuous measurements of changes in firn column density and, since spring 2015, mass balance at multiple sites in the percolation zone of the Jakobshavn Isbrae catchment in western Greenland. Surface mass balance is obtained from both snow scale and cosmic ray sensors, providing cross-validation. Following a description of the multiple technologies employed, we assess variations in compaction and surface mass balance in relation to meteorological variables. We then compare our measurements to model estimates and conclude with recommendations for continued and expanded observational activities.
