A Joint Inversion Method of Wave and Wind Field Parameters Based on SAR SLC Data

Abstract

Synthetic aperture radar (SAR) is an important method for observing the ocean wind field and waves on the sea surface. For most SAR wind field and wave parameter inversion methods, third-party data are required to provide initial information, such as reference wind direction and first guess spectrum. This makes it impossible for SAR to observe ocean wind fields and waves independently. To solve this problem, this letter proposes a joint inversion method based on Sentinel-1 SAR SLC data. In this method, the wind direction is inverted by the LG method, and the wave propagation direction extracted by the SAR image cross-spectrum is used to remove the 180° ambiguity of the wind direction inversion result. The inverted wind direction is used as the reference wind direction in the CMOD5.N method to invert wind speed. Then, the first guess spectrum constructed using the inverted wind speed and inverted wind direction is input into the MPI method to invert the wave spectrum and wave parameters. The wind field and wave parameter inversion results are compared with the European Center for Medium-Range Weather Forecast (ECMWF) ERA5 reanalysis data. The wind field and wave parameter inversion results are in good agreement with the ERA5 data under medium or high sea conditions.