Abstract:
The FY-3E satellite launched in July 2021, which is the world"s first civilian twilight orbit meteorological satellite. The WindRAD dual-frequency scatterometer it carries has the ability to detect global ocean surface wind fields. This paper first studies the nonlinear relationship between sea surface backscatter and wind field based on FY-3E/WindRAD L1 level observation data, and then establishes geophysical model functions (GMFs) for C- and Ku-band VV/HH polarization wind field retrieval respectively. Based on the maximum likelihood estimation (MLE) method, ocean surface wind field were retrieve from WindRAD scatterometer data. The wind field is validated using ocean buoy, CSCAT and NCEP wind field data. The results show that the wind speed bias between the WindRAD and buoy is about 0.2m/s, and the root-mean-square error (RMSE) is range from 1.20 to 1.44 m/s, which better than 2m/s for operational applications. The wind direction bias and RMSE are range from 1.4 ~ 3.0° and 25.3 ~ 30.0°, respectively. WindRAD and HSCAT wind fields have good consistency, with the RMSE of wind speed between 1.37~1.6m/s and the RMSE of wind direction between 22.9°~25.9°. The RMSE between WindRAD and NCEP wind speed is 1.87~2.12m/s, and the RMSE of wind direction is between 22.3°~27.1°. These results indicate that sea surface wind fields retrieved from WindRAD dual-frequency scatterometer have high accuracy, fully demonstrating the application potential and value of WindRAD payload in global sea surface wind field detection.