Robust Arctic sea-ice influence on the frequent Eurasian cold winters in past decades
Robust Arctic sea-ice influence on the frequent Eurasian cold winters in past decades
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DOI：
10.1038/ngeo2277
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发表时间：
2014-12-01
影响因子：
18.3
通讯作者：
Kimoto, Masahide
中科院分区：
文献类型：
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作者：
Mori, Masato;Watanabe, Masahiro;Kimoto, Masahide
过去十年，尽管全球和年平均地表气温不断上升(3)，但欧亚大陆中纬度地区频繁出现严冬(1,2)。观察表明，这些寒冷的欧亚冬季可能是由北极海冰减少引起的(2,4)，通过激发类似于北极涛动(5)的环流异常。然而，在气候模拟中，尚未发现大气对海冰减少的强烈反应，这可能是由于大气环流的内部能量波动所致(6)。在这里，我们使用由 100 名成员组成的模拟集合，以及由基于观测的海冰浓度异常驱动的大气环流模型来表明，由于巴伦支海-喀拉海海冰减少，欧亚大陆中部出现严冬的可能性增加了一倍多。在我们的模拟中，大气对海冰减少的反应大致独立于北极涛动。再分析数据和我们的模拟都表明，海冰减少导致欧亚大陆阻塞情况更加频繁，这反过来又有利于冷空气平流进入欧亚大陆，从而导致严冬。根据对 22 个气候模型的模拟的进一步分析，我们得出结论，海冰驱动的寒冷冬季不太可能在未来气候变暖中占主导地位，尽管不确定性仍然存在，部分原因是集合规模不足。
Over the past decade, severe winters occurred frequently in mid-latitude Eurasia(1,2), despite increasing global- and annual-mean surface air temperatures(3). Observations suggest that these cold Eurasian winters could have been instigated by Arctic sea-ice decline(2,4), through excitation of circulation anomalies similar to the Arctic Oscillation(5). In climate simulations, however, a robust atmospheric response to sea-ice decline has not been found, perhaps owing to energetic internal fluctuations in the atmospheric circulation(6). Here we use a 100-member ensemble of simulations with an atmospheric general circulation model driven by observation-based sea-ice concentration anomalies to show that as a result of sea-ice reduction in the Barents-Kara Sea, the probability of severe winters has more than doubled in central Eurasia. In our simulations, the atmospheric response to sea-ice decline is approximately independent of the Arctic Oscillation. Both reanalysis data and our simulations suggest that sea-ice decline leads to more frequent Eurasian blocking situations, which in turn favour cold-air advection to Eurasia and hence severe winters. Based on a further analysis of simulations from 22 climate models we conclude that the sea-ice-driven cold winters are unlikely to dominate in a warming future climate, although uncertainty remains, due in part to an insufficient ensemble size.