GF-3 SAR Ocean Wind Retrieval: The First View and Preliminary Assessment

Type Article
Date 2017-07
Language English
Author(s) Wang He1, Yang Jingsong2, Mouche AlexisORCID3, Shao Weizeng4, Zhu Jianhua1, Ren Lin2, Xie Chunhua5
Affiliation(s) 1 : State Ocean Adm, Natl Ocean Technol Ctr, Tianjin 300112, Peoples R China.
2 : State Ocean Adm, Inst Oceanog 1, State Key Lab Satellite Ocean Environm Dynam, Hangzhou 310012, Zhejiang, Peoples R China.
3 : Inst Francais Rech Exploitat Mer, Lab Oceanog Phys & Spatiale, F-29280 Brest, France.
4 : Zhejiang Ocean Univ, Marine Acoust & Remote Sensing Lab, Zhoushan 316000, Peoples R China.
5 : State Ocean Adm, Natl Satellite Ocean Applicat Serv, Beijing 100081, Peoples R China.
Source Remote Sensing (2072-4292) (Mdpi Ag), 2017-07 , Vol. 9 , N. 7 , P. 694 (1-12)
DOI 10.3390/rs9070694
WOS© Times Cited 23
Note This article belongs to the Special Issue Ocean Remote Sensing with Synthetic Aperture Radar
Keyword(s) GF-3, synthetic aperture radar (SAR), ocean surface wind, validation
Abstract

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 wind speed and direction retrievals from GF-3 SAR is carried out against in situ measurements from National Data Buoy Center (NDBC) buoy measurements of National Oceanic and Atmospheric Administration (NOAA). Only the buoys located inside the GF-3 SAR wind cell (1 km) were considered as co-located in space, while the time interval between observations of SAR and buoy was limited to less the 30 min. These criteria yielded 56 co-locations during the period from January to April 2017, showing the Root Mean Square Error (RMSE) of 2.46 m/s and 22.22 degrees for wind speed and direction, respectively. Different performances due to geophysical model function (GMF) and Polarization Ratio (PR) are discussed. The preliminary results indicate that GF-3 wind retrievals are encouraging for operational implementation.

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