Analysis of West Greenland multi-day surface and englacial melt events in relation to radiative and synoptic drivers, 2009-2018.

Authors: Shayne O'Brien*, Texas State University, Thomas J Ballinger, Texas State University, Thomas Mote, University of Georgia, Marco Tedesco, Lamont-Doherty Earth Observatory, Columbia University, Dirk van As, Geological Survey of Denmark and Greenland
Topics: Climatology and Meteorology, Polar Regions
Keywords: Climate, Greenland, Glacier, Circulation, Atmosphere
Session Type: Poster
Day: 4/4/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: No File Uploaded

Four decades of surface melt extent and extreme mass loss have been identified on the Greenland Ice Sheet through satellite monitoring technology, though little is known about the preconditioning atmospheric factors and englacial temperature response to multi-day surface melt events. In this study, daily air temperature observations at 2.6 meters above the ice surface were obtained from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) on-ice weather stations for West Greenland transects at Thule, Upernavik, Kangerlussuaq, Nuuk, and Qassimiut. These data are evaluated for persistent melt events (i.e. days with surface temperature > 0°C). Annual frequencies of these events lasting 3 – 7 consecutive days are identified across the last decade. Using a composite approach, the melt events are then related to temporally overlapping observations of shortwave and longwave radiation fluxes, as well as to the Greenland Blocking Index (mean 500 hPa geopotential height over Greenland), to identify the potential local and large-scale drivers of persistent melt. Analysis of englacial temperature measurements taken from thermistors placed within the ice at ~1m depth intervals to ~10m serves to further understanding of the percolation of meltwater from the surface to depth during surface melt events.

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