南极冰架-海洋相互作用研究综述

本文介绍了近期南极冰架-海洋相互作用的研究进展。冰架底部融化速率大于前缘崩解通量,成为南极冰盖质量损失的首要途径。冰架下的海洋按照底部融化驱动因素的不同,可以分为由高密度陆架水驱动的冷冰腔和由变性绕极深层水驱动的暖冰腔。威德尔海的菲尔希纳-龙尼冰架和罗斯海的罗斯冰架属于冷冰腔,占南极冰架总面积的2/3,却只贡献了15%的净融化;东南太平洋扇区阿蒙森海和别林斯高晋海等若干属于暖冰腔的小型冰架,虽然只占南极冰架总面积的8%,却贡献了超过一半的冰架融水。以往看做冷冰腔的东南极托滕冰架和埃默里冰架,也相继发现有变性绕极深层水进入冰腔并造成底部融化。冰架对海洋有冷却和淡化的作用。冷冰腔输出的冰架水具有海洋中最低的温度,对南极陆架水性质乃至南极底层水的形成都有影响。冰架融化加剧,可能是近期观测到的南极底层水淡化的原因。

A review of ice shelf-ocean interaction in Antarctica

Recent advances in the research of ice shelf–ocean interactions in Antarctica are reviewed in this paper. Basal melt rate of ice shelves exceeds calving flux, making bottom melt the dominant cause of mass loss in Antarctic ice sheets. Cavities under ice shelves can be classified into cold cavities-basal melt is driven by dense shelf water-and warm cavities-basal melt is driven by modified Circumpolar Deep Water. The giant Filchner–Ronne and Ross Ice Shelves in the Weddell and Ross Seas cover two-thirds of the total ice shelf area in Antarctica but mass loss from their cold cavities accounts for only 15% of the net melting of all ice shelves combined. Half of the net melting comes from several small, warm-cavity ice shelves in the Amundsen and Bellingshausen Seas in the Southeast Pacific sector, which cover 8% of the total ice shelf area. Modified Circumpolar Deep Water has been found to cause melting in the cold cavities under the Totten and Amery Ice Shelves in East Antarctica. Ice shelves cool and freshen seawater in their cavities. Ice shelf water from cavities is at a very low temperature and will modify shelf waters and even contribute to the formation of Antarctic Bottom Water. The recently observed freshening of Antarctic Bottom Water in the Pacific and Indian sectors might be attributed to the enhanced basal melting of upstream ice shelves.