资源环境科技发展态势分析平台

We addressed the variations of surface melt in Greenland in association with summertime atmospheric conditions from 2000 to 2014. We quantified melt as the number of melt days (NMD), cumulative and maximum melt extent (based on microwave radiometer data), and modeled melt amount. Interannual variations of the maximum melt extent, occurring in timescales of days, differed from those in NMD, cumulative melt extent, and modeled melt amount, which accumulate over the entire melt season. Averaged over the Greenland ice sheet, interannual variations in total column water strongly correlated with NMD (squared correlation coefficient 0.83), cumulative melt extent (0.84), and modeled melt amount (0.82). Significant but less strong correlations were detected between NMD and the Greenland Blocking Index, NMD and North Atlantic Oscillation Index, as well as the modeled melt amount and NAOI. The NMD was strongly linked with the strength of the total column water anomaly in the coastal areas. In individual summers, positive anomalies in southerly winds coincided with positive NMD anomalies. At the eastern coast, positive NMD anomalies occurred under stronger downslope winds, suggesting that subsidence heating dominated over cold-air advection from the inner ice sheet. Differences between the summers of extreme melt in 2012 and minimal melt in 2013 were partly explained by the larger (smaller) occurrence of air masses of southwesterly (southeasterly) origin in 2012 than 2013 at northeastern Greenland. For the 15-year period, the occurrence of northeasterly air-mass origin at Summit was the variable with strongest (negative) correlation with the maximum melt extent.