Variability in the ice sheet elevations over Antarctica derived from repetitive SARAL/AltiKa radar altimeter data (2013a??2016)

摘要

Changes in surface elevations of polar ice sheets are the result of changes in ice dynamics and surface mass balance. Here, we present intra- and inter-annual elevation changes over the Antarctic ice sheet using the AltiKa radar altimetera??s 40 Hz geophysical data record products for the period 2013a??2016. Slope corrections were applied on the elevations using a digital elevation model (DEM) available from NASAa??s ice, cloud and land elevation satellite (ICESat). Comparison of elevations from AltiKa and ICESata??s DEM yielded correlation, bias and root-mean-square-deviation values of the order of 0.99, a??2.88 and 23.04 m, respectively, indicating the first-level accuracy of a former dataset. Further comparison of Airborne Topographic Mapper dataset with AltiKa derived elevation yielded 0.4 m root-mean-square-deviation over a part of Vostok subglacial lake. The intra-annual change indicates that for GY2 (glaciological year), GY3 and GY4, number of negative elevation change points exceeded the number of positive elevation change points during the Antarctic austral summer period (Decembera??February). Inter-annual elevation changes were negative during 2013a??2014 and positive during 2014a??2015 over east Antarctica, whereas in west Antarctica negative elevation changes were observed for both periods.