Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry

Since 2002, the Envisat radar altimeter has measured the elevation of the Antarctic ice sheet with a repeat cycle of 35 days. This long and regular time series is processed using an along-track algorithm to depict in detail the spatial and temporal pattern of elevation change for the whole ice sheet. We use this dataset to examine the spatial and temporal pattern of Pine Island Glacier (PIG) thinning and compare it to the neighbouring glaciers. We also examine additional areas, especially in East Antarctica whose mass balance is poorly known. One advantage of the finer along-track spacing of measurements is that it reveals places of dynamic thinning in regions of rapid ice flow. We observe the acceleration of thinning on PIG. Over the entire basin, the volume loss increased from 7 km(3) a(-1) during 2002-06 to similar to 48 km(3) a(-1) during 2006-10. We also observe accelerated thinning on the lower tens of kilometres of Thwaites Glacier, with a mean thinning of 0.18 m a(-1) over its entire basin during our observation period. We confirm the dynamic thinning of Totten Glacier but we do not detect significantly accelerated thinning on any glacier elsewhere than on the coast of the Amundsen Sea.