Antarctic ice-mass balance 2003 to 2012: regional reanalysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment based on GPS uplift rates

• Published in: The cryosphere 2013-09, Vol.7 (5), p.1499-1512
• Main Authors: Sasgen, I, Konrad, H, Ivins, E. R, Van den Broeke, M. R, Bamber, J. L, Martinec, Z, Klemann, V
• Format: Article
• Language: English
• Subjects: Antarctica; Cryospheres; Drainage basins; Estimates; Freshwater; Global Positioning System; GRACE (experiment); Gravimetry; Ice sheets; Land; Marine; Satellites
• ISSN: 1994-0424; 1994-0416; 1994-0424; 1994-0416
• DOI: 10.5194/tc-7-1499-2013

We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS) from satellite observations of the Gravity and Climate Experiment (GRACE) for time period January 2003 to September 2012. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by mass movement in the Earth interior caused by ice advance and retreat during the last glacial cycle. Here, we develop an improved glacial-isostatic adjustment (GIA) estimate for Antarctica using newly available GPS uplift rates, allowing us to more accurately separate GIA-induced trends in the GRACE gravity fields from those caused by current imbalances of the AIS. Our revised GIA estimate is considerably lower than previous predictions, yielding an estimate of apparent mass change of 53 plus or minus 18 Gt yr super(-1). Therefore, our AIS mass balance of -114 plus or minus 23 Gt yr super(-1) is less negative than previous GRACE estimates. The northern Antarctic Peninsula and the Amundsen Sea sector exhibit the largest mass loss (-26 plus or minus 3 Gt yr super(-1) and -127 plus or minus 7 Gt yr super(-1), respectively). In contrast, East Antarctica exhibits a slightly positive mass balance (26 plus or minus 13 Gt yr super(-1)), which is, however, mostly the consequence of compensating mass anomalies in Dronning Maud and Enderby Land (positive) and Wilkes and George V Land (negative) due to interannual accumulation variations. In total, 6% of the area constitutes about half the AIS imbalance, contributing 151 plus or minus 7 Gt yr super(-1) (ca. 0.4 mm yr super(-1)) to global mean sea-level change. Most of this imbalance is caused by ice-dynamic speed-up expected to prevail in the near future.