Imaging mesoscale upper ocean dynamics using synthetic aperture radar and optical data
Imaging mesoscale upper ocean dynamics using synthetic aperture radar and optical data
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DOI：
10.1029/2011jc007492
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发表时间：
2012-04-19
影响因子：
3.6
通讯作者：
Collard, Fabrice
中科院分区：
文献类型：
--
作者：
Kudryavtsev, Vladimir;Myasoedov, Alexander;Collard, Fabrice
提出了一种高分辨率海洋合成孔径雷达（SAR）和成像光谱仪数据（包括红外通道）的协同定量分析方法。该方法首先清楚地表明，由太阳闪光图像得出的海面粗糙度异常与SAR粗糙度异常相比非常好。利用这些精细分辨率（类似于1公里）的观测结果进一步揭示，导出的粗糙度异常场在空间上与海温场的急剧梯度相关。为了定量解释SAR和光学（可见光和红外范围）图像，推导了将“表面粗糙度”特征与上层海洋流动特征联系起来的方程。随着发展，预计在海面观测和海面流场散度之间有直接联系。从这些卫星观测中，发现强烈的横锋动力学和垂直运动发生在海温场的急剧水平梯度附近。作为一种合理的机制，认为风驱动的上层与准地转流场的相互作用（通过Ekman平流和混合机制）导致次级地转环流的产生，使地面流辐合发散。提出的协同方法结合海温、太阳闪烁亮度和雷达后向散射异常，可能辅以其他卫星数据（如测高、散射测量、海洋颜色），因此可以提供一致的、定量的地表流辐合/散度（上升流/下升流）的位置和强度。这反过来又为从二维卫星表面表达式定量解释上层海洋动力学的进展迈出了重要的一步。
A synergetic approach for quantitative analysis of high-resolution ocean synthetic aperture radar (SAR) and imaging spectrometer data, including the infrared (IR) channels, is suggested. This approach first clearly demonstrates that sea surface roughness anomalies derived from Sun glitter imagery compare very well to SAR roughness anomalies. As further revealed using these fine-resolution (similar to 1 km) observations, the derived roughness anomaly fields are spatially correlated with sharp gradients of the sea surface temperature (SST) field. To quantitatively interpret SAR and optical (in visible and IR ranges) images, equations are derived to relate the "surface roughness" signatures to the upper ocean flow characteristics. As developed, a direct link between surface observations and divergence of the sea surface current field is anticipated. From these satellite observations, intense cross-frontal dynamics and vertical motions are then found to occur near sharp horizontal gradients of the SST field. As a plausible mechanism, it is suggested that interactions of the wind-driven upper layer with the quasi-geostrophic current field (via Ekman advective and mixing mechanisms) result in the generation of secondary ageostrophic circulation, producing convergence and divergence of the surface currents. The proposed synergetic approach combining SST, Sun glitter brightness, and radar backscatter anomalies, possibly augmented by other satellite data (e.g., altimetry, scatterometry, ocean color), can thus provide consistent and quantitative determination of the location and intensity of the surface current convergence/divergence (upwelling/downwelling). This, in turn, establishes an important step toward advances in the quantitative interpretation of the upper ocean dynamics from their two-dimensional satellite surface expressions.