The Chinese Gaofen-3 (GF-3) synthetic aperture radar (SAR) launched by the China\nAcademy of Space Technology (CAST) has operated at C-band since September 2016. To date,\nwe have collected 16/42 images in vertical-vertical (VV)/horizontal-horizontal (HH) polarization,\ncovering the National Data Buoy Center (NDBC) buoy measurements of the National Oceanic and\nAtmospheric Administration (NOAA) around U.S. western coastal waters. Wind speeds from NDBC\nin situ buoys are up to 15 m/s and buoy-measured significant wave height (SWH) has ranged\nfrom 0.5 m to 3 m. In this study, winds were retrieved using the geophysical model function\n(GMF) together with the polarization ratio (PR) model and waves were retrieved using a new\nempirical algorithm based on SAR cutoff wavelength in satellite flight direction, herein called\nCSAR_WAVE. Validation against buoy measurements shows a 1.4/1.9 m/s root mean square error\n(RMSE) of wind speed and a 24/23% scatter index (SI) of SWH for VV/HH polarization. In addition,\nwind and wave retrieval results from 166 GF-3 images were compared with the European Centre\nfor Medium-Range Weather Forecasts (ECMWF) re-analysis winds, as well as the SWH from the\nWaveWatch-III model, respectively. Comparisons show a 2.0 m/s RMSE for wind speed with a\n36% SI of SWH for VV-polarization and a 2.2 m/s RMSE for wind speed with a 37% SI of SWH\nfor HH-polarization. Our work gives a preliminary assessment of the wind and wave retrieval\nresults from GF-3 SAR images for the first time and will provide guidance for marine applications of\nGF-3 SAR.
Loading....