Wetland Monitoring With GNSS-R/IR: Theoretical Simulations with First-Order Radiative Transfer Equation Model

GNSS-R (Global Navigation Satellite System-Reflectomery) has emerged as a new and promising remote sensing techniques. In the recent two years, several airborne experimental campaigns have been carried out to demonstrate the possibility of wetland monitoring by GNSS-R. However, to our knowledge, there are no theoretical models for this new application. As for GNSS-R, whose working mode is an essential bistatic radar, the received power is DDM (Delay Doppler Map). A wetland GNSS-reflections simulator is presented. This model is based on the integral bistatic radar equation by taking into consideration the wetland, system impulse responses and geometry observation system. The wetland parameters affect the DDM waveforms through the BRCS (bistatic radar cross sections), which is a function of soil (surface roughness, soil moisture, soil freeze/thaw state) and vegetation parameters (vegetation moisture, biomass and growth). The simulator contains the inundated wetlands including two kinds of Aspen, whose effects on the final GNSS reflected power (DDM) can be predicted by the simulator. The developed simulator can assist as mechanism tools for wetland monitoring with GNSS-R technique, and this model can provide theoretical backup for wetland mapping, data analysis and experiment design.