20080201 /data1/ws/essay/pinegl/pineglas20070608.la.tex plots in /data1/ws/essay/pinegl/plots/pineglasplots backup in /data5/ws/essay/pinegl Elevation Changes in Pine Island Glacier, Walgreen Coast, Antarctica, based on GLAS (2003) and ERS-1 (1995) Altimeter Data Analyses and Glaciological Implications Ute C. Herzfeld 1 , Patrick McBride 1 , Jay Zwally 2 , and John DiMarzio 3 1 Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309-0449, USA e-mail: Herzfeld@tryfan.colorado.edu 2 Ice Branch, NASA Goddard Space Flight Center, Code 614.1, Greenbelt, MD 20771, USA 3 SGT Inc., NASA Goddard Space Flight Center, Code 614.1, Greenbelt, MD 20771, USA Corresponding Author: Ute Herzfeld CIRES University of Colorado Boulder Boulder, Colorado 80309-0449 USA e-mail: Herzfeld@tryfan.colorado.edu phone: +1-303-735-5164 fax: +1-303-492-2468 ABSTRACT The Geoscience Laser Altimeter System (GLAS) aboard ICESat, launched in January 2003, has been de- signed to detect and monitor changes in the cryosphere. The first objective of this paper is to present high- resolution ice-surface elevation maps derived from GLAS data, using geostatistical analysis. In a regional study of Walgreen Coast and Northern Ellsworth Land, West Antarctica, differences in the representation of geographic and morphologic features in maps based on ERS-1 radar altimeter data and on GLAS data are investigated, with the result that in particular in topographically complex coastal areas and the margin of the ice sheet the improvement in precision and accuracy of the laser altimeter is significant. A second, applied objective is to map elevation changes in Pine Island Glacier, a glacier that plays a key role in the question of stability of the West Antarctic Ice Sheet and has been changing rapidly in recent years. Results of elevation differencing of 2003-GLAS-data and 1995-ERS-1-radar-altimeter-data DEMs (1) show that thinning rates have been increasing and (2) are applied to attribute the observed changes in Pine Island Glacier to internal processes in the glacier, related to dynamic thinning. More generally, this application serves to demonstrate that GLAS data facilitate study of cryospheric change. Keywords: Satellite data, ice dynamics, cryospheric change, geostatistics, satellite data processing 1