The Contribution of Surface and Submesoscale Processes to Turbulence in the Open Ocean Surface Boundary Layer
The Contribution of Surface and Submesoscale Processes to Turbulence in the Open Ocean Surface Boundary Layer
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DOI：
10.1029/2019ms001801
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发表时间：
2019-12-08
影响因子：
6.8
通讯作者：
Garabato, Alberto C. Naveira
中科院分区：
文献类型：
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作者：
Buckingham, Christian E.;Lucas, Natasha S.;Garabato, Alberto C. Naveira
海洋表面边界层是海洋和大气之间进行动量、热量和微量气体交换的关键界面。已知表面过程（风、波浪和浮力强迫）对这一层内的通量有很大贡献。最近的研究表明，发生在小尺度（0.1-10公里，小时到天）的次中尺度过程，因此在大多数海洋模式中还没有体现出来，可能在这些湍流交换中发挥关键作用。虽然在强海流系统和沿岸的区域附近已经证明了对这种现象的观测支持，但在开阔海洋环境中进行的观测相对较少，无法保证在地球系统模型中得到体现。我们使用新的观测和模拟来量化的贡献，表面和亚中尺度过程湍流动能（TKE）耗散在开放的海洋表面边界层。我们的观测结果来自2012年12月至2013年4月在北大西洋的系泊，并得到大气再分析的补充。我们发展了一个概念框架，由于地面和次中尺度过程的耗散率。使用这个框架和观察到的耗散率比较，我们发现，表面过程占主导地位的TKE耗散。对称不稳定性的参数化与这个结果是一致的。接下来，我们采用模拟从海洋锋解析模式重建，由于表面过程的耗散超过了1-2个数量级的亚中尺度过程。总之，这些结果表明，亚中尺度过程不会显着改变垂直TKE预算，虽然这种动态可能是气候上的重要性，因为它们能够从海洋中去除能量。
The ocean surface boundary layer is a critical interface across which momentum, heat, and trace gases are exchanged between the oceans and atmosphere. Surface processes (winds, waves, and buoyancy forcing) are known to contribute significantly to fluxes within this layer. Recently, studies have suggested that submesoscale processes, which occur at small scales (0.1-10 km, hours to days) and therefore are not yet represented in most ocean models, may play critical roles in these turbulent exchanges. While observational support for such phenomena has been demonstrated in the vicinity of strong current systems and littoral regions, relatively few observations exist in the open-ocean environment to warrant representation in Earth system models. We use novel observations and simulations to quantify the contributions of surface and submesoscale processes to turbulent kinetic energy (TKE) dissipation in the open-ocean surface boundary layer. Our observations are derived from moorings in the North Atlantic, December 2012 to April 2013, and are complemented by atmospheric reanalysis. We develop a conceptual framework for dissipation rates due to surface and submesoscale processes. Using this framework and comparing with observed dissipation rates, we find that surface processes dominate TKE dissipation. A parameterization for symmetric instability is consistent with this result. We next employ simulations from an ocean front-resolving model to reestablish that dissipation due to surface processes exceeds that of submesoscale processes by 1-2 orders of magnitude. Together, these results suggest submesoscale processes do not dramatically modify vertical TKE budgets, though such dynamics may be climatically important owing to their ability to remove energy from the ocean.