Modeling and Simulation of GNSS-R Observables with Effects of Swell

Global navigation satellite system-reflectometry (GNSS-R) has attracted much attention in remote sensing, such as sea wind speed detection, soil moisture, and sea ice. In order to verify the algorithm of GNSS-R, the simulation of GNSS-R plays an important role in this research field. Delay waveform (DW) and delay-Doppler map (DDM) are the main observables in GNSS-R simulation, and are usually effects by the complex ocean environment, such as wind and swell. Besides the effects of wind, this article focuses on analyzing the influence of swell on the simulation of GNSS-R. In this article, a complex model of DW and DDM is presented with effects of swell. Swell modeled here by narrow-band Gaussian spectrum, and the influence of swell on the sea surface scattering coefficient, which can be calculated using Kirchhoff approximation-geometric optics. Observables obtained from the simulation in the space-borne scene are analyzed. The simulation results show that swell has a stable and significant impact on the simulation of GNSS-R observables. Compared with models under no consideration of swell, the model with effects of swell has higher accuracy.