Mechanism of seasonal Arctic sea ice evolution and Arctic amplification
Mechanism of seasonal Arctic sea ice evolution and Arctic amplification
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DOI：
10.5194/tc-10-2191-2016
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发表时间：
2016-09-22
期刊：
影响因子：
5.2
通讯作者：
Kim, Jinju
中科院分区：
文献类型：
--
作者：
Kim, Kwang-Yul;Hamlington, Benjamin D.;Kim, Jinju
尽管北极扩大的物理机制及其与海冰融化的关系仍存在争议，但海冰消失被认为是北极扩大的主要原因。本文利用逐月ERA中期再分析资料，采用循环平稳经验正交函数分析方法，对北冰洋海冰消融的季节机制和北冰洋海冰的放大效应进行了分析。尽管夏季北冰洋大部分地区的海冰普遍消失，但冬季只有巴伦支海-卡拉海的海冰仍然很薄。由于海冰减少，通过暴露在空气中的海面的过多湍流热通量使大气层变暖。较暖的空气增加了向下的长波辐射，随后增加了表面空气温度，这有利于海面保持无冰状态。这种正反馈机制在拉普特夫海、东西伯利亚海、楚科奇海和波弗特海没有明显的观察到，因为海冰在深秋(11月)重新冻结，然后在冬季有过多的湍流热通量可用于使大气层柱变暖。为了了解巴伦支海、喀拉海和拉普特夫海、东西伯利亚海、楚科奇海和波弗特海之间的具体差异，文中提供了详细的季节热量预算。
Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents-Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.