The Effect of Wind-Wave Growth on SAR-Based Waterline Maps
The Effect of Wind-Wave Growth on SAR-Based Waterline Maps
复制标题
风浪增长对基于 SAR 的水线图的影响
DOI：
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复制
发表时间：
2011
影响因子：
8.2
通讯作者：
P. Hwang
中科院分区：
文献类型：
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作者：
M. Sletten;P. Hwang
在本文中，我们研究了使用合成孔径雷达图像检测海洋和湖泊水线的相关问题。在以前的一份出版物中，对韩国潮滩的陆地P波段AIRSAR图像所指示的水线进行了比较，发现它们之间的偏移约为80至170米。作者推测，这种差异是由于面波的随深度变化的耗散或频散，以及随后布拉格模型所描述的雷达后向散射的调制。在这篇文章中，我们提出了一种基于风浪增长作为距离(即Fetch)的函数的另一种解释。这一新的解释与环境条件、雷达外观几何和面波理论更加一致，同时也解释了在图像中观察到的几个更精细的特征，这些特征在最初的出版物中没有提到。我们的结果表明，探测到的水线位置应该只在一组受限的条件下才是雷达频率的敏感函数，即当所讨论的水体与来袭涌浪隔绝并且唯一存在的表面波是由陆风局部产生的时候。虽然这种情况在沿海海洋中可能相对较少发生，但在对内陆湖泊迎风海岸进行成像时，这种情况似乎很常见，如其他AIRSAR图像所示。这一分析也是对现有的风浪增长理论的遥感验证，该理论以前没有在该领域进行过研究。
In this paper, we investigate an issue related to the use of synthetic aperture radar imagery to detect ocean and lake waterlines. In a previous publication, the waterlines indicated by Land P-band AIRSAR imagery of a tidal flat in South Korea were compared and found to be offset from one another by approximately 80 to 170 m. The authors postulated that the difference was due to depth-dependent dissipation or dispersion of surface waves and the subsequent modulation of the radar backscatter as described by the Bragg model. In this paper, we present an alternative explanation based on the growth of wind waves as a function of distance (i.e., fetch). This new explanation is more consistent with the environmental conditions, radar look geometry, and surface wave theory, while also explaining several finer-scale features observed in the imagery that are not addressed in the original publication. Our results indicate that the detected waterline position should be a sensitive function of radar frequency only under a restricted set of conditions, namely, when the body of water in question is cutoff from incoming swell and the only surface waves present are locally generated by a land breeze. While such conditions may occur relatively infrequently in the coastal ocean, they appear to be common when imaging the windward shores of inland lakes, as illustrated by additional AIRSAR imagery. The analysis also serves as a remote-sensing-based validation of the existing theory for wind-wave growth in a wavenumber regime not previously studied in the field.