Abstract
Abstract. Increased surface melt over the Greenland Ice Sheet (GrIS) is now estimated to account for half or more of the ice sheet's total mass loss. Here, we show that some meltwater is stored, over winter, in buried supraglacial lakes. We use airborne radar from Operation IceBridge between 2009 and 2012 to detect buried supraglacial lakes, and we find that they were distributed extensively around the GrIS margin through that period. Buried supraglacial lakes can persist through multiple winters and are, on average, ~ 1.9 + 0.2 m below the surface. Most buried supraglacial lakes exist with no surface expression of their occurrence in visible imagery. The few buried supraglacial lakes that do exhibit surface expression have a unique visible signature associated with a darker blue color where subsurface water is located. The volume of retained water in the buried supraglacial lakes is likely insignificant compared to the total mass loss from the GrIS, but the water may have important implications locally for the development of the englacial hydrologic system and ice temperatures. Buried supraglacial lakes represent a small but year-round source of meltwater in the GrIS hydrologic system.
Highlights
Annual mass loss from the Greenland Ice Sheet (GrIS) has increased substantially, quadrupling in the last two decades (Shepherd et al, 2012)
Further studies have expanded the links between supraglacial lakes and waterfilled crevasses and the en- and subglacial hydrologic system, clearly showing that surface meltwater can be routed to the bed of the GrIS, affecting ice dynamics (Zwally et al, 2002; Joughin et al, 2008; Catania et al, 2008; Bartholomew et al, 2011; Palmer et al, 2011; Sundal et al, 2011; Hoffman et al, 2011; Tedstone et al, 2013)
It is in these regions where we detect buried lakes that persist for multiple years (Fig. 5). These multi-year detections must be taken in the context that they are detected in areas with high concentrations of supraglacial lakes where Operation IceBridge (OIB) flight lines are repeated in multiple years
Summary
Annual mass loss from the Greenland Ice Sheet (GrIS) has increased substantially, quadrupling in the last two decades (Shepherd et al, 2012). While regional climate models agree relatively well on precipitation amounts across the GrIS (∼ 20 % variance), they still have large discrepancies in melt production, refreezing and runoff (38–83 % variance; Vernon et al, 2013) This is due to differences in the models and to insufficient field observations for quantifying meltwater retention, transport and runoff (Rennermalm et al, 2013). Ohmura et al (1991) attributed the presence of ice plates they observed on the snow surface at West Lake near Swiss Camp, western Greenland, to the persistence of water late into winter, which formed a frozen ice layer and drained. The buried lakes that we identify and map, using radar data, in this paper represent a hitherto understudied proportion of wintertime storage of water
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