Contribution of the deepened Amundsen sea low to the record low Antarctic sea ice extent in February 2022
Contribution of the deepened Amundsen sea low to the record low Antarctic sea ice extent in February 2022
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DOI：
10.1088/1748-9326/acc9d6
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发表时间：
2023-04
影响因子：
6.7
通讯作者：
Shaoyin Wang;Jiping Liu;Xiao Cheng;Dongxia Yang;T. Kerzenmacher;Xinqing Li;Yongyun Hu;P. Braesicke
中科院分区：
文献类型：
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作者：
Shaoyin Wang;Jiping Liu;Xiao Cheng;Dongxia Yang;T. Kerzenmacher;Xinqing Li;Yongyun Hu;P. Braesicke
2022年2月南极海冰面积（SIE）的年度最小值创下了卫星时代的历史新低，2022年2月25日观测到的面积不到200万平方公里，与2014年之前南极SIE略有上升的趋势形成鲜明对比。然而，2021年春季的阿蒙森海低压（ASL）是自1950年以来最深的。根据线性回归模型，非常低的ASL对2022年创纪录的低SIE贡献约60%。本研究进一步探讨了潜在的机制。关于南极洲同步辐射对南极SIE的滞后影响的调查是基于观测数据和最先进的模拟。我们发现：（a）与南风增强相关的加深的ASL加速了春季海冰从南极大陆西部的输出，导致沿海冰穴（开阔水域）的扩大;（b）通过正的冰-海洋反射率反馈，海岸线附近海冰的缺乏增强了上层海洋的太阳能加热，夏季可能会发生进一步的海冰融化。B。具体而言，在2021年春季，最深的ASL伴随着10月和11月罗斯海70° S上空约17.6 × 103 km 2的大海冰面积通量，导致夏季净表面辐射显著增加20-30 W m−2，上层海洋变暖约0.5 K。因此，2021年春季ASL加深对2022年2月南极SIE创历史新低起着至关重要的作用。此外，研究发现，拉尼娜现象和平流层极涡的强烈影响对2021年的强ASL有显著贡献。目前，在耦合模式相互比较项目第六阶段中，近2/3的地球系统模式难以捕捉ASL和南极SIE之间的关系。
The annual minimum Antarctic sea ice extent (SIE) in February 2022 hits a record low in the satellite era, with less than 2 million square kilometres observed on 25 February 2022, contrasting with the slightly positive trend in the Antarctic SIE prior to 2014. However, the preceding Amundsen Sea Low (ASL) in austral spring 2021 was the deepest since 1950. According to a linear regression model, the very low ASL contributed about 60% to the record low SIE in 2022. This study further investigates the underlying mechanism. The investigation of the lagged impact of the ASL on Antarctic SIE is based on observational data and state-of-the-art simulations. We found that (a) the deepened ASL associated with strengthened southerly winds accelerates the sea ice export away from the western Antarctic continent in spring, leading to the expansion of coastal polynyas (open water areas); (b) through the positive ice-ocean albedo feedback, the lack of the sea ice off the coastline enhances solar heating in the upper ocean and further sea ice melting in summer can occur. Specifically, in spring 2021, the deepest ASL is accompanied by a large sea-ice area flux of about 17.6 × 103 km2 across 70° S over the Ross Sea in October and November, contributing to a significant increase in net surface radiation of 20–30 W m−2 and upper ocean warming of about 0.5 K in summer. Therefore, the deepened ASL in spring 2021 plays a crucial role for the record low Antarctic SIE in February 2022. In addition, it is found that both the La Niña conditions and the strong stratospheric polar vortex contributed significantly to the very strong ASL in 2021. Currently, nearly 2/3 of Earth system models in the Coupled Model Intercomparison Project Phase 6 have difficulties capturing the relationship between the ASL and the Antarctic SIE.