Abstract
Abstract. This study focuses on the present-day surface elevation of the Greenland and Antarctic ice sheets. Based on 3 years of CryoSat-2 data acquisition we derived new elevation models (DEMs) as well as elevation change maps and volume change estimates for both ice sheets. Here we present the new DEMs and their corresponding error maps. The accuracy of the derived DEMs for Greenland and Antarctica is similar to those of previous DEMs obtained by satellite-based laser and radar altimeters. Comparisons with ICESat data show that 80% of the CryoSat-2 DEMs have an uncertainty of less than 3 m ± 15 m. The surface elevation change rates between January 2011 and January 2014 are presented for both ice sheets. We compared our results to elevation change rates obtained from ICESat data covering the time period from 2003 to 2009. The comparison reveals that in West Antarctica the volume loss has increased by a factor of 3. It also shows an anomalous thickening in Dronning Maud Land, East Antarctica which represents a known large-scale accumulation event. This anomaly partly compensates for the observed increased volume loss of the Antarctic Peninsula and West Antarctica. For Greenland we find a volume loss increased by a factor of 2.5 compared to the ICESat period with large negative elevation changes concentrated at the west and southeast coasts. The combined volume change of Greenland and Antarctica for the observation period is estimated to be −503 ± 107 km3 yr−1. Greenland contributes nearly 75% to the total volume change with −375 ± 24 km3 yr−1.
Highlights
Ice sheet surface topography and changes thereof are of great interest to glaciologists for several reasons
Uncertainties derived by differencing ICESat data points and the CryoSat-2 derived new elevation models (DEMs) are less than 4 m ± 25 m for areas of less than 1◦
The deviations from previous DEMs are small except in the area between 86◦ S and 88◦ S, where our data set is significantly improved by the further southward reaching coverage of the CryoSat-2 data
Summary
Ice sheet surface topography and changes thereof are of great interest to glaciologists for several reasons. The large across-track spacing prohibits observations of small-scale spatial patterns Another source of elevation measurements over the ice sheets are radar altimeters carried by the ESA satellites ERS1/2 and ENVISAT, which have been operating since the early nineties. In addition to the dense track spacing and the smaller data gap around the South Pole, CryoSat-2 features the high accuracy in sloped terrain due to the newly developed SIRAL instrument. This capability is a significant improvement compared to the conventional altimeters on board ERS1/2/ENVISAT and enables continuous observations along the relatively steep and narrow margins of the ice sheets as well as on large glaciers and ice caps, where elevation change is most rapid.
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