Generalized radar scattering model including terrain topography

Terrain topography is of great importance for vegetated areas given that even small slopes impact and alter the radar wave interactions between the ground and the overlying vegetation. Current missions generally exclude pixels with large topographic slopes or disregard the terrain topography entirely, potentially accumulating substantial modeling errors and therefore impacting the retrieval performance over such sloped pixels. A flexible and modular radar scattering model has been developed: it describes multispecies vegetation over an N-layered soil with rough interfaces and considers a two-dimensional slope. Simulation results show the impact of a two-dimensional slope for a range of tilt angles: a 3 degree tilt in the plane of incidence translates to a change of up to 6 dB in HH, 2 dB in VV and 1 dB in HV for the total radar backscatter. The terrain topography is shown to be crucial for accurate forward modeling, especially over forested areas.