Radar Detections of Buried Supraglacial Lakes Across the Greenland Ice Sheet
Friday, 19 December 2014: 9:15 AM
Surface melt over the Greenland Ice Sheet (GrIS) is increasing and estimated to account for half or more of the total mass loss. Little, however, is known about the hydrologic pathways that route surface melt within the ice sheet. Radar imaging provides a tool to investigate the englacial water storage and pathways across the GrIS. Here, we present data from the Center for Remote Sensing of Ice Sheets’ radars flown by NASA’s Operation IceBridge (OIB). OIB flights occur in the spring, before significant GrIS melt. The airborne radar echograms collected in the supraglacial lake regions show a unique attenuation signal attributed to over-winter storage of water, referred to here as buried lakes. The Snow Radar (~2-8 Ghz), that images the top 10’s of meters of the ice sheet at high vertical resolution in the snow/firn (~4 cm), is used to map the spatial extent and depth of the retained water along OIB flight lines from 2009-2012. The buried lakes are distributed extensively around the margin of the GrIS. The subsurface water can persist through multiple winters and is, on average, ~4.2 + 0.4 m below the surface. Most buried lakes have no visible surface expression at the time of overflight but the few buried lakes that are visible have a unique visible signature associated with a darker blue color where subsurface water is located. The volume of retained water in the buried lakes is small compared to the total mass loss from the GrIS but the water will have important implications locally for the development of the englacial hydrologic network, ice temperature profiles and glacial dynamics. The buried lakes represent a year-round source of meltwater in the GrIS englacial hydrologic system.