Seasonal Evolution of Supraglacial Lakes on a Major East Antarctic Outlet Glacier

Abstract

Supraglacial lakes (SGLs) are ponds of water that develop in topographic undulations on glaciers and ice sheets during the ablation season. They have been extensively studied in Greenland and, to a lesser extent, the Antarctic Peninsula, where they are thought to influence ice motion and ice shelf stability. In East Antarctica, however, we have limited understanding of SGLs and very few reports of their existence. Using 153 optical satellite scenes and meteorological records from 2000-2013, this study provides a multi-year analysis of the evolution of SGLs and associated melt features on an East Antarctic outlet glacier - Langhovde glacier - in Dronning Maud Land (69°11'S, 39°32'E). The focus is on four variables (number of lakes, total lake area, mean lake area, and number of surface channels) which are mapped at a temporal resolution of just a few days to a few weeks over the 13 ablation seasons. The results demonstrate that the surface hydrological network of Langhovde Glacier is highly dynamic, with significant inter-annual variability in the four measured variables. SGLs are shown to exist on both the floating ice tongue and the grounded ice sheet, developing up to 18.1 km inland of the grounding line and at an elevation of ~670 m. Three pathways of lake evolution are identified: (i) refreezing of SGLs, (ii) in situ drainage on the floating ice tongue during peak temperatures, and (iii) overspilling of SGLs into supraglacial channels located on the grounded and floating ice. The possibility of lakes draining on the grounded ice sheet is also explored and tentatively suggested. Thus, the behaviour of these SGLs show strong similarities to those observed on Greenland and the Antarctic Peninsula, suggesting that they may currently (or in the near future) affect surface energy balance and seasonal ice sheet dynamics in some regions of East Antarctica.