Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters
Comparison of Geophysical Model Functions for SAR Wind Speed Retrieval in Japanese Coastal Waters
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DOI：
10.3390/rs5041956
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发表时间：
2013-04
期刊：
影响因子：
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通讯作者：
Yuko Takeyama;T. Ohsawa;K. Kozai;C. Hasager;Merete Badger
中科院分区：
文献类型：
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作者：
Yuko Takeyama;T. Ohsawa;K. Kozai;C. Hasager;Merete Badger
本文讨论了日本沿海沃茨卫星合成孔径雷达（SAR）图像反演海面风速的地球物理模型函数（GMF）的精度，其特点是短距离和可变的大气稳定度条件。利用平冢和白滨两个验证站的现场观测资料，对CMOD（C波段模式）4、CMOD_IFR 2、CMOD_5和CMOD_5.N反演的海面风速进行了比较。在所有的地球物理模型函数（GMF）中，最新的C波段GMF，CMOD 5.N，在两个站点具有最小的偏差和均方根误差。所有的GMF表现出负偏差的反演风速。为了理解这种偏差的原因，所有SAR反演的风速分为两类：陆上风（从海上吹到陆地）和海上风（从陆地吹到海上）。只有离岸风被发现表现出大的负偏差，从海岸线的短取可能是一个可能的原因。此外，还阐明了在不稳定和稳定条件下，CMOD 5.N都具有大气稳定有效性，并且在中性条件下可以保持与CMOD 5相同的精度。简而言之，目前，CMOD 5.N被认为是最有前途的GMF的SAR风速反演与大气稳定度校正在日本沿海沃茨，虽然有足够的空间，为未来的改善，从短期的效果。
This work discusses the accuracies of geophysical model functions (GMFs) for retrieval of sea surface wind speed from satellite-borne Synthetic Aperture Radar (SAR) images in Japanese coastal waters characterized by short fetches and variable atmospheric stability conditions. In situ observations from two validation sites, Hiratsuka and Shirahama, are used for comparison of the retrieved sea surface wind speeds using CMOD (C-band model)4, CMOD_IFR2, CMOD5 and CMOD5.N. Of all the geophysical model functions (GMFs), the latest C-band GMF, CMOD5.N, has the smallest bias and root mean square error at both sites. All of the GMFs exhibit a negative bias in the retrieved wind speed. In order to understand the reason for this bias, all SAR-retrieved wind speeds are separated into two categories: onshore wind (blowing from sea to land) and offshore wind (blowing from land to sea). Only offshore winds were found to exhibit the large negative bias, and short fetches from the coastline may be a possible reason for this. Moreover, it is clarified that in both the unstable and stable conditions, CMOD5.N has atmospheric stability effectiveness, and can keep the same accuracy with CMOD5 in the neutral condition. In short, at the moment, CMOD5.N is thought to be the most promising GMF for the SAR wind speed retrieval with the atmospheric stability correction in Japanese coastal waters, although there is ample room for future improvement for the effect from short fetch.