Totten Glacier Active Source Experiment

The Totten Glacier (TG) system drains 10% of the East Antarctic Ice Sheet [Rignot and Thomas, 2002], with enough ice to cause global sea level to rise by 6 m [Roberts et al., 2011]. TG has undergone substantial modulation of both flow and ice thickness since 1989 [Li et al. 2016], with retreat of the grounding line observed since 1996 [Li et al. 2015]; however, the origins of the changes remain poorly understood. This uncertainty hampers the reliable quantification of future risk due to the fact that only a few days of fieldwork have been undertaken on the glacier in the last four decades. We aim to improve our understanding of ice-ocean interactions and the mass balance of the TG system through acquiring new ground-based data across the ice shelf and grounding zone region, and also reoccupying nearby historic geophysical sites [Allen and Whitworth, 1970]. In particular, we aim to undertake simultaneous measurements of ice shelf basal melting and velocity, as well as map firn depth-density, basal geometry, subglacial conditions and reoccupy geophysical sites from the 1960s to quantify both current and long-term changes in the glacier system. The specific objectives of this research are to: 1. Measure basal melt (or freeze-on) and firn compaction (or thickening), and determine the degree of ice-ocean interactions beneath the ice shelf using autonomous phase-sensitive radar (ApRES) at a series of locations on the ice shelf and grounded ice to evaluate ice-shelf/ocean models of the region 2. Determine the tidal influence on ice dynamics, capture ice flow velocities and determine the limits of where the ice shelf is in isostatic equilibrium in the grounding zone region 3. Map the geometry of the ocean cavity, capture ocean stratification and map firn densification through the use of active seismic across the ice shelf 4. Characterise the subglacial environment and its role in ice dynamics through the use if active seismic data along the grounding zone region of TG.