Ocean circulation beneath Larsen C Ice Shelf, Antarctica from in situ observations

Abstract

Hot-water drilled access holes were used to obtain oceanographic data from beneath two sites on Larsen C Ice Shelf, one in the north and one in the south. At both sites the entire water column was colder than the surface freezing point, and the temperature-salinity characteristics are consistent with a High Salinity Shelf Water source of maximum salinity 34.65 psu. At the southern site the 0.0°C thermal driving at the ice base and the 0.2-ms -1 rms water speed resulted in a melt rate of 1.30.2m a -1, as measured over an eight-day period. When combined with the available ship-based data, the evidence suggests that the sub-ice cavity is flushed only by water at the surface freezing point. This implies that the reported decrease in surface elevation of Larsen C Ice Shelf is unlikely to be a result of thinning due to an increasing rate of basal melting.