Author(s):
Thomas Overly, Graduate Research Assistant* - Center for Remote Sensing of Ice Sheets, University of Kansas
Abstract:
Due to the technical and physical difficulties involved, it is not known yet whether the Greenland ice sheet is shrinking or growing. Current estimates of snow accumulation on Greenland have large errors (20-25%) because they are derived from a relatively sparse network of point measurements (Ohmura and Reeh, 1991; Bales et al., 2001). Traditional point measurement techniques (snow pits, manual probes, shallow firn cores) are limited in space and often do not represent the region surrounding them due to spatial variability caused by surface slope and deposition and erosion by wind (Maurer, 2006). To determine whether the Greenland ice sheet mass is increasing or decreasing and how this will affect the global sea level, The Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas has developed several ice penetrating radar systems. Ground-based ultra-wideband radar (500-2000 MHz) operated near Summit, Greenland (72.5789 N, 38.4597W) in July, 2005 is used to map near-surface internal layers to a depth of about 150 m with 10 cm range resolution. Radar paths connecting GRIP and GISP2 ice cores enable accurate dating of accumulation radar layers. The accumulation layers are then compared with measurements taken from the ice core site, and statistical and spatial analysis is then conducted to determine the distance from the ice core at which the two sets of measurements become uncorrelated. This analysis provides an improved understanding of spatial variability and accumulation rates in the Summit region.
