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
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
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DOI：
10.5194/tc-7-1499-2013
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发表时间：
2013-09
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通讯作者：
I. Sasgen;H. Konrad;E. Ivins;M. Broeke;J. Bamber;Z. Martinec;V. Klemann
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文献类型：
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作者：
I. Sasgen;H. Konrad;E. Ivins;M. Broeke;J. Bamber;Z. Martinec;V. Klemann
摘要。我们根据重力恢复与气候实验（GRACE）卫星观测结果，给出了2003年1月至2012年9月期间南极冰盖（AIS）25个流域的区域尺度质量平衡。卫星重力测量对南极冰盖质量平衡的估算受到末次冰期循环期间冰进和冰退所引起的地球内部质量运动的强烈影响。在此，我们利用新获取的全球定位系统（GPS）抬升速率，对南极的冰川均衡调整（GIA）进行了改进估算，从而能够更准确地将GRACE重力场中由冰川均衡调整引起的趋势与由南极冰盖当前失衡所引起的趋势区分开来。我们修正后的冰川均衡调整估算值比先前的预测值低得多，得出的表观质量变化估算值为每年53±180亿吨。因此，我们得出的南极冰盖质量平衡为每年 -114±230亿吨，没有先前GRACE估算的那么负。南极半岛北部和阿蒙森海中区域的质量损失最大（分别为每年 -26±30亿吨和 -127±70亿吨）。相比之下，东南极呈现出略微正的质量平衡（每年26±130亿吨），然而，这主要是由于年际积累变化导致毛德皇后地和恩德比地（正）以及威尔克斯地和乔治五世地（负）的质量异常相互补偿的结果。总体而言，6%的区域约占南极冰盖失衡的一半，对全球平均海平面变化的贡献为每年151±70亿吨（约每年0.4毫米）。这种失衡大部分是由预计在不久的将来会普遍存在的冰动力学加速所导致的。
Abstract. 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 ± 18 Gt yr−1. Therefore, our AIS mass balance of −114 ± 23 Gt yr−1 is less negative than previous GRACE estimates. The northern Antarctic Peninsula and the Amundsen Sea sector exhibit the largest mass loss (−26 ± 3 Gt yr−1 and −127 ± 7 Gt yr−1, respectively). In contrast, East Antarctica exhibits a slightly positive mass balance (26 ± 13 Gt yr−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 ± 7 Gt yr−1 (ca. 0.4 mm yr−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.