Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography
Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography
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DOI：
10.1038/ngeo2350
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发表时间：
2015-03-01
影响因子：
18.3
通讯作者：
Bacon, Sheldon
中科院分区：
文献类型：
--
作者：
Rippeth, Tom P.;Lincoln, Ben J.;Bacon, Sheldon
北冰洋最大的海洋热量输入来自大西洋水的流入。这些流入的水比过去2000年来的温度更高(1，2)。然而，这种高温的命运仍然不确定(3)，部分原因是海水相对较咸，因此密度较高：因此，它在中等深度进入北冰洋，并通过分层与表层水域分开。北冰洋盆地内的垂直混合一般很弱，热通量(0.05-0.3W m(-2))很小，主要来自双扩散(4-8)。然而，地理上有限的观测表明，粗糙地形上的湍流混合率显著增强(9-14)。在这里，我们介绍了湍流动能耗散的泛北极微结构测量。我们的测量进一步表明，增强的大陆坡耗散率，也就是垂直混合，随着地形陡度和经度的变化而显著变化。此外，我们的观测表明，耗散对海冰条件不敏感。我们认为潮汐是支持增强耗散的主要能量来源，它产生了超过50Wm(-2)的垂直热通量。我们认为，随着北冰洋海冰的减少，动量从大气向海洋的转移增加，可能会导致未来北冰洋混合热点的扩大。
The largest oceanic heat input to the Arctic Ocean results from inflowing Atlantic water. This inflowing water is warmer than it has been in the past 2,000 years(1,2). Yet the fate of this heat remains uncertain(3), partly because the water is relatively saline, and thus dense: it therefore enters the Arctic Ocean at intermediate depths and is separated from surface waters by stratification. Vertical mixing is generally weak within the Arctic Ocean basins, with very modest heat fluxes (0.05-0.3 W m(-2)) arising largely from double diffusion(4-8). However, geographically limited observations have indicated substantially enhanced turbulent mixing rates over rough topography(9-14). Here we present pan-Arctic microstructure measurements of turbulent kinetic energy dissipation. Our measurements further demonstrate that the enhanced continental slope dissipation rate, and by implication vertical mixing, varies significantly with both topographic steepness and longitude. Furthermore, our observations show that dissipation is insensitive to sea-ice conditions. We identify tides as the main energy source that supports the enhanced dissipation, which generates vertical heat fluxes of more than 50 W m(-2). We suggest that the increased transfer of momentum from the atmosphere to the ocean as Arctic sea ice declines is likely to lead to an expansion of mixing hotspots in the future Arctic Ocean.