Antarctic offshore polynyas linked to Southern Hemisphere climate anomalies
Antarctic offshore polynyas linked to Southern Hemisphere climate anomalies
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DOI：
10.1038/s41586-019-1294-0
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发表时间：
2019-06-20
期刊：
影响因子：
64.8
通讯作者：
Talley, Lynne D.
中科院分区：
文献类型：
--
作者：
Campbell, Ethan C.;Wilson, Earle A.;Talley, Lynne D.
南极洲近海的冰间冰穴--冬季海冰覆盖层上的大开口--被认为是通过对流混合使深海热量快速通风而得以维持的。这些罕见的现象可能会改变深海的性质和环流，但其形成机制尚不清楚。在这里，我们表明，并发上层海洋预处理和气象扰动负责在南大洋威德尔海地区的冰穴的外观。自1976年以来在Maud Rise海山附近形成的最大的polynyas期间于2016年和2017年收集的自主剖面浮标观测结果显示，polynyas是由强烈风暴的通过引发和调制的，强烈的热量损失导致了它们内部的深层翻转。创纪录强度的风力驱动的上涌削弱了上层海洋的盐度分层，从而有利于2016年和2017年的不稳定。我们表明，以前的威德尔冰穴可能是在类似的异常条件下发展起来的，这与南半球气候变率的模式，预计加强人为气候变化的结果。
Offshore Antarctic polynyas -large openings in the winter sea ice cover-are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. Autonomous profiling float observations-collected in 2016 and 2017 during the largest polynyas to form near the Maud Rise seamount since 1976 -reveal that the polynyas were initiated and modulated by the passage of severe storms, and that intense heat loss drove deep overturning within them. Wind-driven upwelling of record strength weakened haline stratification in the upper ocean, thus favouring destabilization in 2016 and 2017. We show that previous Weddell polynyas probably developed under similarly anomalous conditions, which are associated with a mode of Southern Hemisphere climate variability that is predicted to strengthen as a result of anthropogenic climate change.