Radar imaging of intense nonlinear Ekman divergence
Radar imaging of intense nonlinear Ekman divergence
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DOI：
10.1002/2016gl070799
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发表时间：
2016-09
影响因子：
5.2
通讯作者：
Guoqiang Liu;W. Perrie;V. Kudryavtsev;Yijun He;Hui Shen;Biao Zhang;Haibo Hu
中科院分区：
文献类型：
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作者：
Guoqiang Liu;W. Perrie;V. Kudryavtsev;Yijun He;Hui Shen;Biao Zhang;Haibo Hu
一般来说，在海洋热锋存在的情况下，海表温度（SST）梯度与地面风之间存在很强的正相关性，并且海洋热锋暖侧的海洋大气边界层不稳定。墨西哥湾流是海洋热锋的一个显著例子，其温暖的一面在合成孔径雷达（SAR）图像中经常被检测为增强的后向散射。然而，在一些“异常”SAR图像中，有时在锋的暖侧观察到低后向散射，这似乎不一致。因此，我们提出了一种机制来解释低后向散射的产生，海洋表面风浪和强烈的非线性Ekman散度之间的相互作用的基础上。这种机制的验证表明，在所观察到的异常SAR图像的模式是在良好的协议与那些在模拟的雷达签名。此外，这种方法和分析表明，SAR是潜在的重要检测和诊断小尺度海气相互作用和上层海洋动力学与强烈的垂直输送引起的亚中尺度过程。
In general, given an oceanic thermal front, there is a strong positive correlation between sea surface temperature (SST) gradients and surface winds, and the marine atmospheric boundary layer is unstable over the warm side of the oceanic thermal front. The Gulf Stream is a notable example of an oceanic thermal front, and its warm side is often detected as enhanced backscatter in synthetic aperture radar (SAR) images. However, in some “anomalous” SAR images, low backscatter is sometimes observed on the warm side of the front, which seems inconsistent. Therefore, we propose a mechanism to interpret the generation of the low backscatter, based on interactions between ocean surface wind waves and intense nonlinear Ekman divergence. This mechanism is verified by showing that patterns in an observed anomalous SAR image are in good agreement with those in the simulated radar signature. In addition, this methodology and analysis demonstrate that SAR is potentially important for detecting and diagnosing small scale air‐sea interactions and upper ocean dynamics with strong vertical transports induced by submesoscale processes.