Airborne and ground-based geophysical evaluation of the surface and englacial hydrological system of the Sørsdal Glacier, East Antarctica, and implications for ice-shelf stability

Large swathes of the margin of the East Antarctic Ice Sheet experience pronounced surface melting during the austral summer. The nature and temporal evolution of evolving surface hydrological systems are poorly known, however, as are their potential connections with englacial and subglacial water systems and their effects on ice dynamics. We have acquired helicopter-based ground-penetrating radar (GPR), electrical self-potential (SP), broadband passive seismic and GNSS data to delineate the geometry and monitor the temporal evolution of the subsurface hydrological system of the marine-terminating Sørsdal Glacier, Princess Elizabeth Land, East Antarctica, between the austral summers of 2017-18 and 2018-19. Our data reveal the presence of a shallow englacial hydrological system that is connected to surface lakes upstream of the grounding line and, surprisingly, is active not only in the austral summer but also through the Antarctic winter. Here we illustrate the spatial and temporal characteristics of the englacial hydrological system and its susceptibility to tidal forcing through the Antarctic winter. Our observations are consistent with persistent year-round redistribution of mass from grounded to floating portions of at the East Antarctic margin, with far-reaching consequences for ice shelf stability.