Oceanic regimes at the ice fronts of George VI Sound, Antarctic Peninsula

Abstract

The basal melting of George VI Ice Shelf into the unusually warm underlying water represents a major oceanographic feature in the waters off the west coast of the Antarctic Peninsula. Limited temperature, salinity and other data have previously been available from the northern ice front of the ice shelf and a mechanism has been proposed for the circulation and melting there. A synoptic dataset from the northern ice front has now been obtained by a continuously measuring CTD probe. The cross-sectional profiles prepared from these data support the suggested model and show that this circulation can account for two thirds of the basal ice melt required for mass balance of the ice shelf. Further measurements, with the profiling CTD instrument, with sample bottles and reversing thermometers, and with an Aanderaa RCM4 current meter, have extended coverage to the southern ice front. The oceanographic regime there is similar to that in the north below 500 m and it appears that communication occurs between the northern and southern regions at this depth. Clear evidence of basal melting is observed in the T-S characteristics at the southern ice front but the waters of the region are not described by a unique T-S curve as they are in the north. More detailed investigation of the southern area is required before estimates of the actual melt rates for the entire ice shelf will be possible.