Improved ice loss estimate of the northwestern Greenland Ice Sheet

2003-2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data [Zwally et al., 2011]. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change estimate, we supplement the ICESat data with altimeter surveys from NASA’s Airborne Topographic Mapper (ATM) from 2002-2010 [Krabill et al., 2011] and NASAs Land, Vegetation and Ice Sensor (LVIS) from 2010 [Blair and Hofton, 2010].

The airborne data are mainly concentrated along the ice margin and thus have a significant impact on the estimate of the volume change. Our results show that adding ATM and LVIS data to the ICESat data increases the catchment-wide estimate of ice volume loss by 11 percent, mainly due to an improved volume loss estimate along the ice sheet margin. Furthermore, our results show a significant acceleration in mass loss at elevations above 1200 m. Both the improved mass loss estimate along the ice sheet margin and the acceleration at higher elevations have implications for predictions of the elastic adjustment of the lithosphere caused by present-day ice mass changes. Our study shows that the use of ICESat data alone to predict elastic uplift rates biases the predicted rates by several millimeters per year at GPS locations along the north-western coast.