Research on GNSS-R Ocean Wind Speed Orthorectification Technique

Global Navigation Satellite System Reflectometry (GNSS-R) is a technique for obtaining surface information such as sea surface wind speed, effective wave height and so on by receiving and comparing the differences in amplitude, phase and frequency between the direct GNSS signals and the reflected signals from the surface. The traditional GNSS-R ocean wind speed normalisation method is mainly based on physical models such as Elfouhaily wave spectrum and Kirchhoff Approximation-Geometric Optics (KA-GO) geometric optics approximation, but these models are not only complicated and inefficient in the computation process, but the inaccuracy of the model itself also leads to a bias in the normalisation results. deviation of the orthotropic results. Aiming at this problem, this paper proposes a parametric model-based GNSS-R ocean wind speed orthorectification method, which replaces the traditional physical model by establishing a parametric model between the sea surface wind speed and the scattering coefficient. The simulation validation is carried out in the range of 0-30 m/s wind speed, and the results show that the root mean square error of the time-delayed Doppler power image is no more than 2.2% and the correlation coefficient reaches 0.97, while the computation speed is improved by 1.42 times, compared with the traditional physical model, which verifies the feasibility and validity of the parameterised model orthorectification method.