GEOMETRY, MOTION AND MASS-BALANCE OF DYER PLATEAU, ANTARCTICA

Geodetic surveying and ground-based radar profiling were used to deter mine geometry and surface motion of the ice sheet on the Dyer Plateau, Antarctica. in the vicinity of an ice-core site on a local dome. Vert ical strain measurements in the core hole constrain the depth profile of vertical velocity. These geophysical measurements are used to analy ze the profiles of density and annual layer thickness measured on the ice core to estimate the current mass balance of the ice column and th e past history of accumulation rate. Consideration of horizontal and v ertical mass-flow divergence shows that the profiles of density and ve rtical velocity are not fully consistent with steady state. Mean densi ty of the fim layer appears to be increasing, which leads to the deduc tion of a small rate of mass increase (approximate to 0.02 m a(-1) ice -equivalent thickness). Over the last 200 a there has been a gradual i ncrease in accumulation rate from about 0.46 m a(-1) to 0.54 m a(-1) i ce-equivalent thickness in recent time.