Radar imaging of intense nonlinear Ekman divergence

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• 作者：Guoqiang Liu ; William Perrie ; Vladimir Kudryavtsev ; Yijun He ; Hui Shen ; Biao Zhang ; Haibo Hu
• 刊名：Geophysical Research Letters
• 出版年：2016
• 出版时间：28 September 2016
• 年：2016
• 卷：43
• 期：18
• 页码：9810-9818
• 全文大小：520.9KB
• ISSN：1944-8007

文摘

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.