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Development of Wind Speed Retrieval from Cross-Polarization Chinese Gaofen-3 Synthetic Aperture Radar in Typhoons
Development of Wind Speed Retrieval from Cross-Polarization Chinese Gaofen-3 Synthetic Aperture Radar in Typhoons
Weizeng Shao 1 , Xinzhe Yuan 2,*, Yexin Sheng 1 , Jian Sun 3,Wei Zhou 4 and Qingjun Zhang 5
1 Marine Science and Technology College, Zhejiang Ocean University, Zhoushan 316022, China;
shaoweizeng@zjou.edu.cn (W.S.); shengyexin@hotmail.com (Y.S.)
2 National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China
3 Physical Oceanography Laboratory/CIMST, Ocean University of China and Qingdao National Laboratory
for Marine Science and Technology, Qingdao 266100, China; sunjian77@ouc.edu.cn
4 South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;
zhouwei@scsio.ac.cn
5 Beijing Institute of Spacecraft System Engineering, Beijing 100076, China; ztzhangqj@163.com
* Correspondence: harley_yuan@mail.nsoas.org.cn; Tel.: +86-010-6210-5661
Received: 25 December 2017; Accepted: 29 January 2018; Published: 31 January 2018

Abstract: The purpose of our work is to determine the feasibility and effectiveness of retrieving sea surface wind speeds from C-band cross-polarization (herein vertical-horizontal, VH) Chinese Gaofen-3 (GF-3) SAR images in typhoons. In this study, we have collected three GF-3 SAR images acquired in Global Observation (GLO) and Wide ScanSAR (WSC) mode during the summer of 2017 from the China Sea, which includes the typhoons Noru, Doksuri and Talim. These images were collocated with wind simulations at 0.12 grids from a numeric model, called the Regional Assimilation and Prediction System-Typhoon model (GRAPES-TYM). Recent research shows that GRAPES-TYM has a good performance for typhoon simulation in the China Sea. Based on the dataset, the dependence of wind speed and of radar incidence angle on normalized radar cross (NRCS) of VH-polarization GF-3 SAR have been investigated, after which an empirical algorithm for wind speed retrieval from VH-polarization GF-3 SAR was tuned. An additional four VH-polarization GF-3 SAR images in three typhoons, Noru, Hato and Talim, were investigated in order to validate the proposed algorithm. SAR-derived winds were compared with measurements fromWindsat winds at 0.25 grids with wind speeds up to 40 m/s, showing a 5.5 m/s root mean square error (RMSE) of wind speed and an improved RMSE of 5.1 m/s wind speed was achieved compared with the retrieval results validated against GRAPES-TYM winds. It is concluded that the proposed algorithm is a promising potential technique for strong wind retrieval from cross-polarization GF-3 SAR images without encountering a signal saturation problem.

Keywords: wind speed; typhoon; cross-polarization; Gaofen-3 SAR




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发布时间:2018-09-23