Scatter of mass changes estimates at basin scale for Greenland and Antarctica
Scatter of mass changes estimates at basin scale for Greenland and Antarctica
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DOI：
10.5194/tc-7-1411-2013
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发表时间：
2013-01-01
期刊：
影响因子：
5.2
通讯作者：
Forsberg, R.
中科院分区：
文献类型：
--
作者：
Barletta, V. R.;Sorensen, L. S.;Forsberg, R.
在过去的十年中，GRACE任务为确定格陵兰和南极冰盖的质量变化提供了宝贵的数据。然而，已公布的质量平衡结果仍然存在差异，缺乏对误差和差异来源的全面分析。在这里，我们展示了格陵兰和南极冰盖在盆地尺度上由GRACE数据得出的月度质量变化和趋势，我们评估了每个可能的差异来源的可变性和误差，并以前所未有的系统方式进行了这项工作，考虑到了质量推断方法、数据集和背景模型。我们发现由两种独立方法得出的月质量变化结果之间有很好的一致性，这代表了交叉验证。对于月度解，我们发现大部分散射是由使用两个不同的数据集而不是应用的两种不同的方法造成的。除了众所周知的GIA趋势不确定性外，我们发现地心运动和最近的去走样校正对趋势的影响很大，南极洲的贡献分别为+13.2GT年(-1)和-20GT年(-1)，南极洲受这些影响比格陵兰岛更大。我们显示了版本RL04和新版本RL05的使用差异，并确认了新版本中的噪音含量较低。解的总体离散性远远超过了数据误差和泄漏所传播的不确定性(如过去所做的)；因此，我们为每月的解和趋势计算了新的合理的总误差。我们发现，由于采用不同的地心运动时间序列估计(1度改正)而导致的月度解的离散性是显著的--贡献了高达40%的总误差。在整个宽限期(2003-2011年)，我们对格陵兰的趋势估计为-234+/-20GT年(-1)，南极洲为-83+/-36GT年(-1)(西部为-111+/-15GT年(-1))。我们还发现，在过去的四年里，质量损失明显增加(就我们的错误而言)。
During the last decade, the GRACE mission has provided valuable data for determining the mass changes of the Greenland and Antarctic ice sheets. Yet, discrepancies still exist in the published mass balance results, and comprehensive analyses on the sources of errors and discrepancies are lacking. Here, we present monthly mass changes together with trends derived from GRACE data at basin scale for both the Greenland and Antarctic ice sheets, and we assess the variability and errors for each of the possible sources of discrepancies, and we do this in an unprecedented systematic way, taking into account mass inference methods, data sets and background models. We find a very good agreement between the monthly mass change results derived from two independent methods, which represents a cross validation. For the monthly solutions, we find that most of the scatter is caused by the use of the two different data sets rather than the two different methods applied. Besides the well-known GIA trend uncertainty, we find that the geocenter motion and the recent de-aliasing corrections significantly impact the trends, with contributions of +13.2 Gt yr(-1) and -20 Gt yr(-1), respectively, for Antarctica, which is more affected by these than Greenland. We show differences between the use of release RL04 and the new RL05 and confirm a lower noise content in the new release. The overall scatter of the solutions well exceeds the uncertainties propagated from the data errors and the leakage (as done in the past); hence we calculate new sound total errors for the monthly solutions and the trends. We find that the scatter in the monthly solutions caused by applying different estimates of geocenter motion time series (degree-1 corrections) is significant - contributing with up to 40% of the total error. For the whole GRACE period (2003-2011) our trend estimate for Greenland is -234 +/- 20 Gt yr(-1) and -83 +/- 36 Gt yr(-1) for Antarctica (-111 +/- 15 Gt yr(-1) in the western part). We also find a clear (with respect to our errors) increase of mass loss in the last four years.