Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction
Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction
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DOI：
10.1002/grl.50260
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发表时间：
2013-03-16
影响因子：
5.2
通讯作者：
Messias, Marie-Jose
中科院分区：
文献类型：
--
作者：
Meredith, Michael P.;Brown, Peter J.;Messias, Marie-Jose
来自南大洋的稠密海水更新了大西洋下部颠覆的环流，其中很大一部分流经斯科舍海。我们在这里报告了致密的底层，其温度和盐度的梯度与在南大洋表面附近看到的相当。它们是由层结较弱的地层覆盖的，是由南斯科舍省海脊上密集水域的间歇性溢出和深海沟内的地形圈闭造成的。其中一层被发现比上面的水至少老了34年。据估计，这一层的垂直扩散系数比以前报道的盆地平均深度混合要小得多。我们推测：(A)Scotia海的垂直混合在空间上是强烈不均匀的，(B)这些层的冲刷，就像它们的形成一样，与溢流事件有关，因此也是强烈的幕式。
The lower limb of the Atlantic overturning circulation is renewed by dense waters from the Southern Ocean, a substantial portion of which flow through the Scotia Sea. We report dense bottom layers here, with gradients in temperature and salinity comparable to those seen near the surface of the Southern Ocean. These are overlain by layers with much weaker stratification, and are caused by episodic overflows of dense waters across the South Scotia Ridge, and topographic trapping within deep trenches. One such layer was found to be at least 34 years older than the water immediately above. The estimated vertical diffusivity to which this layer was subject is substantially less than the strong basin-average deep mixing reported previously. We conjecture that (a) vertical mixing in the Scotia Sea is strongly spatially inhomogeneous, and (b) the flushing of these layers, like their formation, is related to overflow events, and hence also strongly episodic.