Future surface mass balance and surface melt in the Amundsen sector of the West Antarctic Ice Sheet
Future surface mass balance and surface melt in the Amundsen sector of the West Antarctic Ice Sheet
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DOI：
10.5194/tc-15-571-2021
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发表时间：
2021-02-08
期刊：
影响因子：
5.2
通讯作者：
Chekki, Mondher
中科院分区：
文献类型：
--
作者：
Donat-Magnin, Marion;Jourdain, Nicolas C.;Chekki, Mondher
我们根据 10 公里分辨率的区域模型，在 RCP8.5 情景下对 2080-2100 年南极西部表面质量平衡 (SMB) 和地表融化进行了预测。我们的预测是通过在当前模型边界条件中添加 CMIP5（耦合模型比对项目第五阶段）多模型平均季节性气候变化异常来构建的。使用异常有利于减少 CMIP5 模型偏差，完美模型测试表明，尽管对预计的 SMB 和融化速率低估了 16%-17%，但我们的方法捕获了未来变化的大部分特征。Getz 和 Abbot 之间区域接地冰盖上的 SMB 从 1989-2009 年的 336 Gt yr(-1) 增加到 2009 年的 455 Gt yr(-1)。 2080-2100年，全球海平面变化率将减少0.33毫米yr(-1)。由于温暖条件下饱和水蒸气压的增加、海冰浓度的减少以及海洋空气侵入的增加，降雪量确实使近地表变暖增加了 7.4% 到 8.9% C-1。冰架表面融化速率在 21 世纪增加了一个数量级，主要是由于湿度增加导致向下辐射增加以及融化时反照率降低。东部冰架（阿博特、科斯格罗夫和派恩岛）有表面液态水净生产，但西部冰架（思韦茨、克罗森、多森和盖茨）没有。这是通过融雪比的演变来解释的：在我们的模拟中，低于 0.60 至 0.85 的阈值时，空气中的融水并未完全耗尽，而在更高的比率下，会发生完全耗尽和地表液态水的净产生。这表明，在RCP8.5条件下，西部冰架可能在一个多世纪内不会受到水力压裂的影响，而东部冰架在本世纪末之前具有很高的水力压裂潜力。
We present projections of West Antarctic surface mass balance (SMB) and surface melt to 2080-2100 under the RCP8.5 scenario and based on a regional model at 10 km resolution. Our projections are built by adding a CMIP5 (Coupled Model Intercomparison Project Phase 5) multi-model-mean seasonal climate-change anomaly to the present-day model boundary conditions. Using an anomaly has the advantage to reduce CMIP5 model biases, and a perfect-model test reveals that our approach captures most characteristics of future changes despite a 16 %-17 % underestimation of projected SMB and melt rates.SMB over the grounded ice sheet in the sector between Getz and Abbot increases from 336 Gt yr(-1) in 1989-2009 to 455 Gt yr(-1) in 2080-2100, which would reduce the global sea level changing rate by 0.33 mm yr(-1). Snowfall indeed increases by 7.4 % degrees C-1 to 8.9 % degrees C-1 of near-surface warming due to increasing saturation water vapour pressure in warmer conditions, reduced sea-ice concentrations, and more marine air intrusion.Ice-shelf surface melt rates increase by an order of magnitude in the 21st century mostly due to higher downward radiation from increased humidity and to reduced albedo in the presence of melting. There is a net production of surface liquid water over eastern ice shelves (Abbot, Cosgrove, and Pine Island) but not over western ice shelves (Thwaites, Crosson, Dotson, and Getz). This is explained by the evolution of the melt-to-snowfall ratio: below a threshold of 0.60 to 0.85 in our simulations, firn air is not entirely depleted by melt water, while entire depletion and net production of surface liquid water occur for higher ratios. This suggests that western ice shelves might remain unaffected by hydrofracturing for more than a century under RCP8.5, while eastern ice shelves have a high potential for hydrofracturing before the end of this century.