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GF-3 SAR Ocean Wind Retrieval: The First View and Preliminary Assessment ArchiMer
Wang, He; Yang, Jingsong; Mouche, Alexis; Shao, Weizeng; Zhu, Jianhua; Ren, Lin; Xie, Chunhua.
Gaofen-3 (GF-3) is the first Chinese civil C-band synthetic aperture radar (SAR) launched on 10 August 2016 by the China Academy of Space Technology (CAST), which operates in 12 imaging modes with a fine spatial resolution up to 1 m. As one of the primary users, the State Oceanic Administration (SOA) operationally processes GF-3 SAR Level-1 products into ocean surface wind vector and plans to officially release the near real-time SAR wind products in the near future. In this paper, the methodology of wind retrieval at C-band SAR is introduced and the first results of GF-3 SAR-derived winds are presented. In particular, the case of the coastal katabatic wind off the west coast of the U.S. captured by GF-3 is discussed. The preliminary accuracy assessment of...
Tipo: Text Palavras-chave: GF-3; Synthetic aperture radar (SAR); Ocean surface wind; Validation.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00396/50731/51435.pdf
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Preliminary Analysis of Chinese GF-3 SAR Quad-Polarization Measurements to Extract Winds in Each Polarization ArchiMer
Ren, Lin; Yang, Jingsong; Mouche, Alexis; Wang, He; Wang, Juan; Zheng, Gang; Zhang, Huaguo.
This study analyzed the noise equivalent sigma zero (NESZ) and ocean wind sensitivity for Chinese C-band Gaofen-3 (GF-3) quad-polarization synthetic aperture radar (SAR) measurements to facilitate further operational wind extraction from GF-3 data. Data from the GF-3 quad-polarization SAR and collocated winds from both NOAA/NCEP Global Forecast System (GFS) atmospheric model and National Data Buoy Center (NDBC) buoys were used in the analysis. For NESZ, the co-polarization was slightly higher compared to the cross-polarization. Regarding co-polarization and cross-polarization, NESZ was close to RadarSAT-2 and Sentinel-1 A. Wind sensitivity was analyzed by evaluating the dependence on winds in terms of normalized radar cross-sections (NRCS) and polarization...
Tipo: Text Palavras-chave: Gaofen-3; Synthetic aperture radar; Quad-polarization; Ocean surface wind; Noise equivalent sigma zero; Geophysical model function; Polarization ratio; Polarization difference.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00420/53104/54059.pdf
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Error Analysis on ESA's Envisat ASAR Wave Mode Significant Wave Height Retrievals Using Triple Collocation Model ArchiMer
Wang, He; Zhu, Jianhua; Yang, Jingsong.
Nowadays, spaceborne Synthetic Aperture Radar (SAR) has become a powerful tool for providing significant wave height (SWH). Traditionally, validation of SAR derived SWH has been carried out against buoy measurements or model outputs, which only yield an inter-comparison, but not an "absolute" validation. In this study, the triple collocation error model has been introduced in the validation of Envisat ASAR derived SWH products. SWH retrievals from ASAR wave mode using ESA's algorithm are validated against in situ buoy data, and wave model hindcast results from WaveWatch III wave model, covering a period of six years. From the triple collocation validation analysis, the impacts of the collocation distance and water depth on the error of ASAR SWH are...
Tipo: Text Palavras-chave: Envisat ASAR; Significant wave height; Validation; Triple collocation.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00249/36019/34545.pdf
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