A new ocean surface wind field retrieval method from C-band airborne synthetic aperture radar

Abstract

Wind direction retrieval depending on other background sources, e.g., the visible wind-induced streaks, numerical weather prediction model data, scatterometer data and buoy data is the key problem existing in the ocean wind field retrieval using airborne synthetic aperture radar (SAR) data based on geophysical model function which influences the wind speed and direction retrieval accuracies. To solve this problem, a new ocean wind field retrieval method is proposed, with which the wind speed and direction are estimated simultaneously through using the normalized radar cross sections corresponding to different incidence angles and geophysical model function according to the sounding characteristics of airborne SAR. To evaluate the ocean wind field retrieval errors and effects, the simulated data and C band airborne SAR data are used to obtain the wind speed and direction by the proposed method. The verification results show that the wind field retrieval method is suited to retrieve highly accurate wind speed and direction from airborne SAR sounding data without other background sources. The major error can be explained by the insufficient accuracy in calibration of the NRCS for wind speed and wind direction retrieval. The wind speed error increases with the value of speed increasing and at high wind speeds exceeding 18 m/s the error increases distinctly. The value of wind speed has no obvious influence on wind direction retrieval accuracy.