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首页> 外文期刊>Journal of Physical Oceanography >Modeling Bottom Mixed Layer Variability on the Mid-Oregon Shelf during Summer Upwelling
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Modeling Bottom Mixed Layer Variability on the Mid-Oregon Shelf during Summer Upwelling

机译：夏季上升期间俄勒冈中部大陆架底部混合层变化的模拟

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Results from a model of wind-driven circulation are analyzed to study spatial and temporal variability in the bottom mixed layer (BML) on the mid-Oregon shelf in summer 2001. The model assimilates acoustic Doppler profiler velocities from two cross-shore lines of moorings 90 km apart to provide improved accuracy of near-bottom velocities and turbulence variables in the area between the mooring lines. Model results suggest that the response of the BML thickness to upwelling- and downwelling-favorable winds differs qualitatively between an area of "simple" bathymetric slope at 45°N and a wider shelf area east of Stonewall Bank (44.5°N). At 45°N, the BML grows in response to downwelling-favorable conditions, in agreement with known theories. East of Stonewall Bank, the BML thickness is increased following upwelling events. In this area, the southward upwelling jet detaches from the coast and flows over a wider part of the Oregon shelf, creating conditions for Ekman pumping near the bottom. Based on computations of bottom stress curl, the vertical pumping velocity in this area may reach 15 m day~(-1) following periods of intensified upwelling-favorable winds. A column of denser, near-bottom water upwelled over the Ekman flow convergence area is tilted as a result of vertical shear in horizontal velocities, causing unstable stratification and convective overturning. As a result of this process, BML thickness values east of Stonewall Bank can be in excess of 20 m following upwelling, comparable to maximum values at 45°N following downwelling.
机译：分析了来自风循环的模型的结果，以研究2001年夏季俄勒冈中部陆架底部混合层（BML）的时空变化。该模型吸收了两条跨岸系泊缆线的多普勒剖面声速相距90公里，以提高系泊索之间区域内的近底速度和湍流变量的精度。模型结果表明，BML厚度对上升和下降有利风的响应在45°N的“简单”测深坡度区域和Stonewall Bank以东的较宽的陆架区域（44.5°N）之间在质量上有所不同。与已知理论一致，BML在45°N响应于井下有利条件而生长。在斯通沃尔银行以东，随着上升事件的发生，BML厚度增加了。在该区域，向南上升的射流从海岸脱离，流过俄勒冈州陆架的较宽部分，为埃克曼在底部附近抽水创造了条件。根据底部应力卷曲的计算，该区域的垂直抽水速度可能会随着上升上升有利风周期的增加而达到15 m day〜（-1）。由于水平速度的垂直剪切作用，在埃克曼流动汇聚区上流的一列稠密的，接近底部的水被倾斜，从而导致不稳定的分层和对流倾覆。作为此过程的结果，向上流动后，石墙岸以东的BML厚度值可能会超过20 m，与向下流动后在45°N处的最大值相当。

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