Teleconnection between sea ice in the Barents Sea in June and the Silk Road, Pacific–Japan and East Asian rainfall patterns in August
Teleconnection between sea ice in the Barents Sea in June and the Silk Road, Pacific–Japan and East Asian rainfall patterns in August
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DOI：
10.1007/s00376-017-7029-y
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发表时间：
2017-12
影响因子：
5.8
通讯作者：
Shengping He;Yongqi Gao;T. Furevik;Huijun Wang;Fei Li
中科院分区：
文献类型：
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作者：
Shengping He;Yongqi Gao;T. Furevik;Huijun Wang;Fei Li
与以往研究倾向于关注北极海冰总覆盖对东亚夏季三极降雨格局的影响不同，本研究将巴伦支海确定为6月海冰变化对东亚夏季三极降雨格局影响最显着的关键区域。八月三极降雨格局，并探讨了其中的遥相关机制。结果表明，6月海冰的减少激发异常向上的空气运动，由于强大的近地面热力强迫，这进一步触发了一个纬向翻转波状模式延伸到中纬度。因此，异常的向下运动形成里海，这反过来又诱导纬向翻转环流沿着副热带急流，表现出东西Rossby波列被称为丝绸之路模式。研究表明，由于丝绸之路格局向东亚的东延伸，在韩国附近占优势的副热带高压小笠原高压出现了显著的异常。小笠原高压异常作为Hadley环流的一个可能的下降分支，最终触发了太平洋-日本型的纬向翻转。这反过来又导致了异常的反气旋和气旋对在东亚地区，和三极垂直对流异常向东。因此，在东亚地区观测到一个三极降水异常型。使用社区大气模式第5版的数值实验结果支持对这一系列事件的解释。
In contrast to previous studies that have tended to focus on the influence of the total Arctic sea-ice cover on the East Asian summer tripole rainfall pattern, the present study identifies the Barents Sea as the key region where the June sea-ice variability exerts the most significant impacts on the East Asian August tripole rainfall pattern, and explores the teleconnection mechanisms involved. The results reveal that a reduction in June sea ice excites anomalous upward air motion due to strong near-surface thermal forcing, which further triggers a meridional overturning wave-like pattern extending to midlatitudes. Anomalous downward motion therefore forms over the Caspian Sea, which in turn induces zonally oriented overturning circulation along the subtropical jet stream, exhibiting the east–west Rossby wave train known as the Silk Road pattern. It is suggested that the Bonin high, a subtropical anticyclone predominant near South Korea, shows a significant anomaly due to the eastward extension of the Silk Road pattern to East Asia. As a possible descending branch of the Hadley cell, the Bonin high anomaly ultimately triggers a meridional overturning, establishing the Pacific–Japan pattern. This in turn induces an anomalous anticyclone and cyclone pair over East Asia, and a tripole vertical convection anomaly meridionally oriented over East Asia. Consequently, a tripole rainfall anomaly pattern is observed over East Asia. Results from numerical experiments using version 5 of the Community Atmosphere Model support the interpretation of this chain of events.