Melting and deformation of the Ross Ice Shelf, Antarctica, by Multi-Year Phase Sensitive Radio Echo Sounding [article]

Joseph A. Snodgrass, University Of Canterbury
<span title="2021-08-24">2021</span>
Antarctic ice shelves are an important part of the Antarctic ice sheet system, holding back the grounded ice front from accelerating onto the ocean and contributing to sea level rise. As ice shelves float on the ocean, they are the most vulnerable to oceanic and environmental changes. The oceans in the ice shelf cavity remain some of the most unexplored places in the world with only a few observations. The Ross Ice Shelf is the largest ice shelf in the world, buttressing 11.6m of potential sea
more &raquo; ... evel rise within its catchment. This study presents the first precision Autonomous Phase-sensitive Radio Echo Sounding (ApRES) measurements of ice shelf thickness, internal deformation and basal melting across an entire traverse of the Ross Ice Shelf. Autonomous Phase-sensitive Radio Echo Sounding (ApRES) is a ground-based instrument that can record reflections of internal layers and the ice shelf base to millimetre precision using phase-based measurements. The ice shelf thickness change and internal deformation are used to determine basal melting. Phase coherence of stable internal and basal reflectors over the survey period allows this type of analysis. Up to 5 seasons of annual ApRES measurements were collected at 32 locations along the South Pole Overland Traverse (SPOT) and Siple Coast Traverse (SCT). The survey covered a 1000km transect of the Ross Ice Shelf (RIS) from Mina Bluff to the Kamb Ice Stream (KIS). Strong basal reflection strength in the north and southern regions indicated well-defined ice-ocean interfaces formed from basal melting. Weaker reflections and lower apparent thickness across the central RIS sites indicated the presence of marine ice or debris. Basal melting was 0-0.02 m a-1 for a large area of the central RIS, with data gaps where marine ice and debris are present. Basal melting rises to 0.25-0.45 m a-1 at the southern and northern ends of this region due to the expected influence of High Salinity Shelf Water (HSSW) and Antarctic Surface Water (AASW) respectively. Basal melt rates of 0.01-0.04 [...]
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