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Sources of anomalous air masses associated with melting of the Greenland Ice Sheet

Authors: Thomas Mote*, University of Georgia, Lori Wachowicz, University of Georgia, Jonathon Preece, University of Georgia, Kyle Mattingly, Rutgers University, Tom Ballinger, Texas State University
Topics: Cryosphere, Climatology and Meteorology, Polar Regions
Keywords: Greenland, ice melt, air mass
Session Type: Paper
Day: 4/8/2020
Start / End Time: 9:35 AM / 10:50 AM
Room: Virtual Track 2
Presentation File: No File Uploaded

The Greenland Ice Sheet (GrIS) has experienced increased surface melt and mass loss during the past two decades. Surface melt and mass balance are partially driven by large-scale changes in atmospheric circulation, which can direct anomalously warm and moist air masses over the ice sheet and lead to pulses of extensive melt and high runoff rates. However, the processes by which these anomalous air masses are produced in external source regions and transported to the GrIS are poorly understood. Here we examine extreme melt pulses (>95th percentile melt extent for 3 or more days) for several topographically defined regions of the ice sheet since 1979. Daily melt extent is determined from a satellite passive microwave product. The NOAA Air Resources Laboratory HYSPLIT model is used to calculate air parcel back trajectories during periods prior to melt pulses with data from the NASA MERRA2 atmospheric reanalysis. Potential temperature at the dynamic tropopause is used to trace atmospheric motion prior to melt pulses. Particular attention is given to extreme events in July 2012 and July 2019 that led to melting at the highest reaches of the ice sheet. Results show distinct differences in air mass source region for melt pulses east and west of the ice divide and highlight the important role of air masses of North American and European origin in driving rapid melt and mass loss events.

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