The pattern and variability of Antarctic sea-ice drift in the Indian Ocean and western Pacific sectors

Sea-ice drift physically redistributes pack ice and changes ice extent, concentration, and, through deformation, the ice-thickness distribution. In this paper, data are presented from 39 satellite-tracked buoys, deployed during various seasons from 1985 to 1996 in the sea ice of the Southern Ocean off East Antarctica between 20 degrees and 160 degrees E longitude. The dominant features of the ice motion in the region are a westward drift parallel to the bathymetry near the Antarctic continent, a cyclonic circulation cell in Prydz Bay, and eastward drift of the ice to the north of the zonal sheer zone. The oceanic circulation along the coast is generally barotropic and the ice drift is well correlated with bottom topography. Northward outflows, the locations of which are determined by both bottom topography and the seasonally varying position of the zonal shear zone, allow the discharge of sea ice from the westward drift in the south into the northerly belt of eastward flow, but with considerable variability in the net northward ice transport. The ice translation monitored by the buoys is used to derive the spatial pattern of the ice-velocity field. The daily average ice-drift speed in the westward flow is 0.23 m s(-1) (19.8 km d(-1)), with considerable spatial and temporal variability, and in the eastward flow the average is 0.17 m s(-1) (15.1 km d(-1)). Seasonal and interannual ice-drift variabilities are analyzed. The results are compared with satellite data of sea-ice extent and concentration over the same time, as well as with hydrographic observation of the position of the Antarctic Divergence.