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Abstract
The early 21st Century has been characterized by numerous climatic extremes on the Greenland Ice Sheet, with new records set for melt extent and negative surface mass balance. At the same time, the atmospheric circulation over Greenland during the melt season has been characterized by an anomalously high frequency of blocking patterns. Using data from the 20th Century Reanalysis (20CRv2c), and regional climate model Modle Atmosphrique Rgional, a summer 500 hPa geopotential height climatology is constructed for the years 19002014, using self-organizing maps to examine the linkage between atmospheric circulation and both surface energy and surface mass balance. Results show statistically significant increases in synoptic types that favor meltwater production when comparing the 20th and 21st centuries. The Arctic warm period of the early 20th Century is also examined, with results showing statistically significant increases in synoptic types favoring meltwater production when comparing the 1920s to the 1930s.