The yearly paired process of slow growth and rapid melt of some 15 million square kilometers of Antarctic sea ice takes place with a regular asymmetry; the process has been linked to the relationship of the position of the ice edge with the band of low pressure that circles the continent between 60° and 70°S. In autumn, winds to the north of the low-pressure band slow the advancing ice edge. In summer, Ekman divergence created by opposing winds on either side of the low-pressure band opens up warm water regions that rapidly melt sea ice. We use the 40 ensemble members from the CESM-LENS historical run (1920–2005) to examine the relationship between the asymmetry in the annual cycle and the position and intensity of the low-pressure band. CESM-LENS reproduces the magnitude of the annual cycle of Antarctic sea ice extent with a short lag (2 weeks). Melt rate is the characteristic of the annual cycle that varies the most. Our results provide evidence that lower pressure leads to increased melt rates, which supports the importance of the role of divergence in increasing the melt rate of Antarctic sea ice. The role of winds during the growing season remains unquantified.

中文翻译：

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CESM大集合中南极海冰不对称季节循环的驱动机制

每年约 1500 万平方公里的南极海冰缓慢增长和快速融化的配对过程以规则的不对称方式发生；该过程与冰缘位置与环绕大陆的 60° 至 70°S 之间的低压带的关系有关。秋季，低压带以北的风减缓了前进的冰缘。在夏季，由低压带两侧的相反风造成的埃克曼分歧开辟了迅速融化海冰的温水区域。我们使用来自 CESM-LENS 历史运行（1920-2005）的 40 个集合成员来检查年周期中的不对称性与低压带的位置和强度之间的关系。CESM-LENS 以短暂的滞后（2 周）再现了南极海冰范围的年周期幅度。融化率是年周期变化最大的特征。我们的结果提供了证据，表明较低的压力会导致融化速率增加，这支持了分歧在增加南极海冰融化速率中的作用的重要性。风在生长季节的作用仍未量化。