Glacial–interglacial variations in central East Antarctic ice accumulation rates

Abstract

Past rates of ice accumulation in central East Antarctica are defined poorly for the Last Glacial period. Ice cores, from which current estimates are based, are limited in number (there is one deep ice core at Vostok Station, one at Dome F and two others currently being extracted at Dome C and Dronning Maud Land), and are restricted spatially (they are one-dimensional). Here, spatial variations in ice accumulation rates during the Last Glacial are calculated from isochronous internal ice sheet layering, measured by airborne ice penetrating radar data. The layers are used to identify the stratigraphy around five East Antarctic ice domes. Isochrons are dated by linking them to the Vostok ice core and, in one case, the EPICA Dome C ice core. This chronostratigraphy allows the depth–age function to be identified across the ice sheet. A simple ice flow model, using the depth–age measurements as input, is then used to determine the spatial and temporal variation in East Antarctic ice accumulation over the Last Glacial cycle. The lowest rates of ice accumulation were predicted in the full glacial period to the south of Dome A and Ridge B. There are two possible explanations for this: (1) the ice divide topographies may have caused a ‘precipitation shadow’ in the ice age; (2) with the expansion of the Ross ice shelf the area to the south of Dome A and Ridge B would be at the very centre of the ice sheet and, hence, at a maximum distance from the ocean moisture source.