Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
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DOI：
10.1038/ngeo812
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发表时间：
2010-04-01
影响因子：
18.3
通讯作者：
Rintoul, S. R.
中科院分区：
文献类型：
--
作者：
Sallee, J. B.;Speer, K. G.;Rintoul, S. R.
大气和海洋之间的相互作用是由海洋表面的混合层介导的。这一层的深度取决于风的强迫和来自大气的加热。混合层深度的变化影响到大气和海洋深层之间的交换率、海洋储存热量和碳的能力以及支持浮游植物生长的光和营养物质的供应。然而，南大洋混合层对大气变化的反应并不为人所知。在这里，我们分析了Argo剖面浮标的温度和盐度数据，结果表明，南半球大气变化的主要模式南方环形模式（SAM）会导致混合层深度的大规模异常，并且这种异常在纬向上不对称。从一个简单的热收支的混合层，我们得出结论，与偏离的SAM从纬向对称性的纬向风引起异常的热通量，可以反过来解释所观察到的混合层深度和海面温度的变化。我们的研究结果表明，SAM的变化，包括最近和预测的趋势归因于人类活动，驱动南大洋混合层深度的变化，海气交换，海洋封存的热量和碳，以及生物生产力的后果。
Interactions between the atmosphere and ocean are mediated by the mixed layer at the ocean surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper ocean, the capacity of the ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the Southern Ocean mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the Southern Annular Mode (SAM), the dominant mode of atmospheric variability in the Southern Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air-sea exchange, ocean sequestration of heat and carbon, and biological productivity.