Seasonality of submesoscale flows in the ocean surface boundary layer
Seasonality of submesoscale flows in the ocean surface boundary layer
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DOI：
10.1002/2016gl068009
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发表时间：
2016-03-16
影响因子：
5.2
通讯作者：
Belcher, Stephen E.
中科院分区：
文献类型：
--
作者：
Buckingham, Christian E.;Garabato, Alberto C. Naveira;Belcher, Stephen E.
上层海洋中次中尺度流动的一个特征是相对涡度分布的偏斜性。预计会导致高Rossby数流动，这种偏斜对上层海洋内的混合、耗散和层化有影响。作为海洋表面混合实验的一部分，海洋次中尺度相互作用研究(渗透性)显示，尽管Rossby数的尺度小于0.5，但相对涡度在冬季是正偏转的。此外，这种偏斜度在春季和秋季降至零。也有证据表明，梯度Rossby数存在温和的季节变化。提出的相对涡度偏斜的机制是，由逆梯度Richardson数概括的侧向浮力梯度与垂直浮力梯度之比在冬季限制了相对涡度的范围，但在一年中的其他时间限制了它的范围。这些结果支持了最近的观测和模式模拟，表明上层海洋是亚中尺度湍流季节性周期的宿主。
A signature of submesoscale flows in the upper ocean is skewness in the distribution of relative vorticity. Expected to result for high Rossby number flows, such skewness has implications for mixing, dissipation, and stratification within the upper ocean. An array of moorings deployed in the Northeast Atlantic for 1year as part of the experiment of the Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS) reveals that relative vorticity is positively skewed during winter even though the scale of the Rossby number is less than 0.5. Furthermore, this skewness is reduced to zero during spring and autumn. There is also evidence of modest seasonal variations in the gradient Rossby number. The proposed mechanism by which relative vorticity is skewed is that the ratio of lateral to vertical buoyancy gradients, as summarized by the inverse gradient Richardson number, restricts its range during winter but less so at other times of the year. These results support recent observations and model simulations suggesting that the upper ocean is host to a seasonal cycle in submesoscale turbulence.