Frontal Subduction of the Mid-Atlantic Bight Shelf Water at the Onshore Edge of a Warm-Core Ring
Frontal Subduction of the Mid-Atlantic Bight Shelf Water at the Onshore Edge of a Warm-Core Ring
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暖核环陆上边缘大西洋中部湾陆架水的锋面俯冲
DOI：
10.1029/2018jc013794
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Partida, Jacob
中科院分区：
文献类型：
--
作者：
Zhang, Weifeng G.;Partida, Jacob
这项工作研究了大陆架水沿着冲击中大西洋湾大陆架边缘的暖心环的陆上边缘的俯冲。动力学分析的依据是卫星观测和海洋观测台倡议先锋阵列观测台的观测以及理想化的数值模型模拟。它们共同表明，锋生引起的亚中尺度锋俯冲与一阶罗斯比和弗劳德数发生在环的岸上边缘。俯冲流是暖核环向岸迁移的结果，它增强了环和陆架沃茨界面上的密度锋。俯冲是交叉锋次级环流的一部分，试图放松不断增强的密度锋。环和大陆架沃茨的物理和地球化学性质的巨大差异为观察俯冲现象提供了一个很好的机会。在环边流的带动下，俯冲陆架水随后在环水表层之下和表面可见陆架水拖缆旁边被输送到海上。它解释了孤立的地下包的陆架水沿着在斜坡海的环形周边的历史观测。基于模型的估计表明，相对于其他主要形式的陆架水交换，这种类型的俯冲相关的陆架水的地下跨陆架迁移可能是实质性的。本研究还提出，由锋面俯冲作用引起的环边前缘向外扩展可能有助于环边海流夹带陆架水，并增强陆架边缘的陆架水流光输运。
This work studies the subduction of the shelf water along the onshore edge of a warm‐core ring that impinges on the edge of the Mid‐Atlantic Bight continental shelf. The dynamical analysis is based on observations by satellites and from the Ocean Observatories Initiative Pioneer Array observatory as well as idealized numerical model simulations. They together show that frontogenesis‐induced submesoscale frontal subduction with order‐one Rossby and Froude numbers occurs on the onshore edge of the ring. The subduction flow results from the onshore migration of the warm‐core ring that intensifies the density front on the interface of the ring and shelf waters. The subduction is a part of the cross‐front secondary circulation trying to relax the intensifying density front. The dramatically different physical and biogeochemical properties of the ring and shelf waters provide a great opportunity to visualize the subduction phenomenon. Entrained by the ring‐edge current, the subducted shelf water is subsequently transported offshore below a surface layer of ring water and alongside of the surface‐visible shelf‐water streamer. It explains the historical observations of isolated subsurface packets of shelf water along the ring periphery in the slope sea. Model‐based estimate suggests that this type of subduction‐associated subsurface cross‐shelfbreak transport of the shelf water could be substantial relative to other major forms of shelfbreak water exchange. This study also proposes that outward spreading of the ring‐edge front by the frontal subduction may facilitate entrainment of the shelf water by the ring‐edge current and enhances the shelf‐water streamer transport at the shelf edge.