| Summary: | Liquid water at the basal interface of a glacier reduces effective pressure and basal friction thus increasing ice motion. The timing of surface melt reaching the bed is poorly constrained, however. To more accurately predict changes in mass balance across the Greenland Ice Sheet, we require a better understanding of how surface melt drainage varies spatially and temporally. Previous studies have found it possible for liquid water to be stored englacially at Sermeq Kujalleq (Store Glacier) for up to several months. Englacial water storage not only would delay surface melt from reaching the bed, but if storage persists through the winter, it may impact how a glacier responds to surface melt in the subsequent melt season. In general, we lack direct winter observations mainly due to the logistical difficulties of obtaining them. Through autonomous phase-sensitive radio echo sounding (ApRES), a ground-based radar system that can make continuous measurements for up to a year, we can address this challenge. In this thesis, I present ApRES data spanning an 11-month long period from Sermeq Kujalleq. Analyses of englacial radar return power and basal reflectivity indicate a dynamic hydrologic system exists interseasonally and liquid water is potentially stored englacially throughout the winter months. This further emphasizes the need to consider winter-time hydrology and quantify englacial water storage to improve mass balance and ice flow models in Greenland. M.S.
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