Experimental and modelled GNSS reflectometry response over land

The applications of spaceborne GNSS reflectometry data over land are investigated in this work using the data collected by the UK TechDemoSat experimental mission. In order to quantify the sensitivity of the GNSS reflections to biomass and soil moisture from real data it is necessary to extract a quantity, like the surface reflectivity, as much as possible independent from the system parameters. At the same time, to understand the scattering mechanisms and potentialities and limitations of GNSS-R over land, an electromagnetic simulator has to be used and compared to the experimental data. The available simulator was tuned and validated on ground based and airborne data. The satellite platform poses additional problems due to the low magnitude of the reflected signal and to topography effects. These are discussed in the paper.