利用Agro浮标估计南大洋混合的时空变化

Seasonal and Spatial Variations of Southern Ocean Diapycnal Mixing from Argo Profiling Floats

海洋中的湍流跨等密度面混合(以下简称混合)控制着海洋中淡水、热量以及CO2等溶解物质的输运。南大洋是全球湍流混合最强烈的区域之一。理解南大洋湍流混合的时空分布特征对于模拟和预测全球大洋环流和气候变化起着至关重要的作用。目前,部分投放在南大洋的新型Argo浮标已经采用铱星通讯系统传送数据,可以返回垂向高分辨率的水文剖面,从而为研究南大洋的湍流混合提供了前所未有的机遇。本文作者在国际上首次利用这些新型浮标观测得到的高分辨率剖面对湍流混合进行了研究。结果表明,南大洋的混合存在明显的空间分布不均匀性,并且与地形变化密切相关。此外,在地形平坦处,湍流混合表现出明显的季节变化。这种变化主要是由风输入到海洋中的近惯性能量的季节性变化引起的。

Diapycnal mixing controls the transport of heat, salt and biogeochemical properties in the ocean interior. Southern Ocean is thought to be one of the most energet- ic regions for diapycnal mixing in the world ocean. Un- derstanding the spatial and temporal variation of diapyc- nal diffusivity in this region is important for assessing and predicting changes of large-scale ocean circulation and climate. The recent development of Argo profiling floats with Iridium communication system affords greatly increased vertical resolution of water column sampling utilized to estimate diapycnal mixing through finescale parameterizations. Here as the first attempt we use high -resolution hydrographic profiles from these floats to demonstrate that the spatial distribution of the turbulent diapycnal mixing in the upper Southern Ocean is con- trolled by bathymetry via interaction with the Antarctic Circumpolar Current （ ACC） . The seasonal variation of this mixing is largely stirred by surface wind stress through inertial energy input and is more pronounced in the upper ocean over flat topography.