Density-compensated overturning in the Labrador Sea
Density-compensated overturning in the Labrador Sea
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DOI：
10.1038/s41561-019-0517-1
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发表时间：
2020-01
影响因子：
18.3
通讯作者：
Sijia Zou;M. Lozier;Feili Li;R. Abernathey;L. Jackson
中科院分区：
文献类型：
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作者：
Sijia Zou;M. Lozier;Feili Li;R. Abernathey;L. Jackson
气候系统的一个关键组成部分-大西洋经向翻转环流-预计将在世纪减缓，原因是拉布拉多海对流减弱，而拉布拉多海对流本身是对温室气体变暖和/或北极淡水流量增加的反应。然而，亚极地北大西洋翻转计划的首次观测结果显示，2015-2016年冬季，经向翻转环流对拉布拉多海强对流的反应很小。从观测和再分析数据的分析，我们在这里表明，这种弱的响应可以解释由一个强大的密度补偿在拉布拉多海。虽然对流引起的重要变化的温度和盐度在盆地内部，出口的热和盐度异常的边界流主要发生沿着密度面。因此，穿过密度面的转换，即翻转环流的印记，相对较小。这一发现突出了温度和盐度之间的关键关系，在拉布拉多海的倾覆强度的确定，并强调了准确的淡水通量估计改进的经向翻转环流预测的必要性。
The Atlantic Meridional Overturning Circulation, a key constituent of the climate system, is projected to slow down in the twenty-first century due to a weakening of the Labrador Sea convection, itself a response to greenhouse gas warming and/or enhanced freshwater flux from the Arctic. However, the first observations from the Overturning in the Subpolar North Atlantic Program reveal a minimal response of the Meridional Overturning Circulation to the strong Labrador Sea convection during the winters of 2015–2016. From an analysis of the observational and reanalysis data, we show here that this weak response can be explained by a strong density compensation in the Labrador Sea. Although convection induces important changes of temperature and salinity in the basin interior, the export of the thermal and haline anomalies to the boundary current largely takes place along density surfaces. As a result, the transformation across density surfaces, that is, the imprint on the overturning circulation, is relatively small. This finding highlights the critical relationship between temperature and salinity in determining the overturning strength in the Labrador Sea and underlines the necessity of accurate freshwater flux estimates for improved Meridional Overturning Circulation predictions.