The 1979-2005 Greenland ice sheet melt extent from passive microwave data using an improved version of the melt retrieval XPGR algorithm

摘要

Analysis of passive microwave satellite observations over the Greenland ice sheet revealsa significant increase in surface melt over the period 1979-2005. Since 1979,the total melt area was found to have increased +1.22 x 10ˆ7 kmˆ2. An improved versionof the cross-polarized gradient ratio (XPGR) technique is used to identify themelt from the brightness temperatures. The improvements in the melt retrieval XPGRalgorithm as well as the surface melt acceleration are discussed with results from acoupled atmosphere-snow regional climate model. From 1979 to 2005, the ablationperiod increases everywhere over the melt zone except in the regions where the modelsimulates an increased summer snowfall. Indeed, more snowfall in summer decreasesthe liquid water content of the snowpack, raises the albedo and therefore reduces themelt. Finally, this melt acceleration over the Greenland ice sheet is highly correlatedwith both Greenland and global warming suggesting a continuing surface melt increasein the future.