The Role of Eddies in Buoyancy-Driven Eastern Boundary Currents
The Role of Eddies in Buoyancy-Driven Eastern Boundary Currents
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DOI：
10.1175/jpo-d-18-0040.1
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发表时间：
2018-11
影响因子：
3.5
通讯作者：
S. Bire;C. Wolfe
中科院分区：
文献类型：
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作者：
S. Bire;C. Wolfe
利用理想化的涡分辨模式模拟了由大尺度纬向浮力梯度驱动的东部边界流系统。EBC系统由一对堆叠的纬向流组成，在表面附近向极地流动，在中间深度向赤道流动。浮力平流的EBC主要是平衡脱落的涡旋，反气旋，暖心涡旋占主导地位的表面附近和气旋，冷心涡旋发现在中间深度。这些边界涡在东部边界环流中起着重要的作用-通过帮助捕获海岸附近的EBC-和大尺度环流通过其对翻转环流的下降支的影响。使用厚度加权平均框架分析的动量和厚度预算突出了涡形阻力在形成和维持EBC中的作用。在EBC的离岸侧翼处，形状阻力的效率显著增加。形状阻力的这种纬向变化对于保持一个迅速、狭窄的EBC是必不可少的。使用一个简单的，半解析模型的EBC的基本物理说明。
An eastern boundary current (EBC) system driven by a large-scale meridional buoyancy gradient is simulated using an idealized eddy-resolving model. The EBC system consists of a pair of stacked meridional currents that flow poleward near the surface and equatorward at intermediate depths. Buoyancy advection in the EBC is primarily balanced by the shedding of eddies, with anticyclonic, warm-core eddies dominating near the surface and cyclonic, cold-core eddies found at intermediate depths. These boundary eddies play a significant role in both the eastern boundary circulation—by helping to trap the EBC near the coast—and the large-scale circulation through their effect on the downwelling limb of the overturning circulation. Momentum and thickness budgets analyzed using the thickness-weighted average framework highlight the role of eddy form drag in shaping and maintaining the EBC. The efficiency of the form drag increases dramatically at the offshore flank of the EBC. This zonal variation of the form drag is essential for maintaining a swift, narrow EBC. The essential physics of the EBC are illustrated using a simple, semianalytical model.