Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations

Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA Deutsches Zentrum für Luft- und Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 \textpm 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend ( 113 \textpm 17 gigaton/year) from a near balance during the 1990s but is smaller than some other recent estimates.