南极海冰快速下降历史事件的时空特征分析

TEMPORAL AND SPATIAL CHARACTERISTICS OF HISTORICAL EVENTS OF RAPIDDECLINE OF ANTARCTIC SEA ICE

卫星记录以来,南极海冰范围发生5次快速下降事件,研究这5次事件的时空特征,对进一步认识海冰快速下降事件的物理机制具有重要意义。基于海冰范围和海冰密集度的卫星数据,从时间和空间两个维度总结5次南极海冰快速下降事件的特征,再结合大气和海洋各项环境因素的再分析数据,探讨海冰快速下降的影响因素及其驱动过程。结果显示:南极海冰快速下降的空间分布存在季节性差异,2021年8~12月以及2016年8~12月的春季南极海冰快速下降由别林斯高晋海、威德尔海、印度洋和西太平洋区域的海冰减少所主导;2010年12月至2011年4月以及1985年12月至1986年4月的夏季南极海冰快速下降由威德尔海、罗斯海沿岸和西太平洋区域的海冰减少所主导;2008年4~8月的冬季南极海冰快速下降则由别林斯高晋海和西太平洋的部分区域的海冰减少所主导。探究影响海冰的环境因素发现,海表面温度和海表面净热通量对海冰减少的热力效应影响具有区域性差异。此外,南极海冰快速下降受阿蒙森低压的影响,相应的海表面风异常既通过经向热输运的热力效应导致海冰减少,也通过风的动力效应驱动海冰漂移使得海冰密集度降低。

According to the satellite records,there have been five Antarctic sea ice extent rapid declines.Study of the spatial and temporal characteristics of the events is important to understand the mechanism of the sea ice rapid declines.Based on satellite observations of sea ice extent and sea ice concentration,the spatiotemporal characteristics of sea ice rapid declines were summarized.In addition,combined with the atmosphere and ocean reanalysis data,the factors influencing the thermal and dynamic processes that drove the sea ice rapid declines were discussed.Result shows that there was different seasonal locking corresponding to different spatial patterns for the Antarctic sea ice rapid decline events.The spring rapid declines of sea ice in August~December 2021 and August~December 2016 were due to the decrease of sea ice in the Bellingshausen Sea,the Weddell Sea,the Indian Ocean,and the Western Pacific Ocean.The summer rapid declines of sea ice from December 2010 to April 2011 and from December 1985 to April 1986 were due to the loss of sea ice in the Weddell Sea,the Ross Sea coasts,and the Western Pacific Ocean.The winter rapid decline of sea ice in April~August 2008 was caused by the loss of sea ice in the Bellingshausen Sea and parts of the Western Pacific Ocean.By exploring the environmental factors controlling sea ice variability,we found that the influence of sea surface temperature and sea surface net heat flux on the thermodynamic effect of sea ice loss has regional differences.In addition,the Amundsen Low and associated sea surface wind anomalies could not only reduce sea ice through the thermal effect of meridional heat transport,but also reduce sea ice concentration through sea ice drift driven by the dynamic effect of anomalous wind.