Geometry, motion and mass balance of Dyer Plateau, Antarctica

Geodetic surveying and ground-based radar profiling were used to determine 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. Vertical strain measurements in the core hole constrain the depth profile of vertical velocity. These geophysical measurements are used to analyze the profiles of density and annual layer thickness measured on the ice core to estimate the current mass balance of the ice column and the past history of accumulation rate. Consideration of horizontal and vertical mass-flow divergence shows that the profiles of density and vertical velocity are not fully consistent with steady state. Mean density of the firn layer appears to be increasing, which leads to the deduction of a small rate of mass increase (≈ 0.02 m a− 1 ice-equivalent thickness). Over the last 200a there has been a gradual increase in accumulation rate from about 0.46 m a− 1 to 0.54 m a− 1 ice-equivalent thickness in recent time.