Analyzing topography effects for L-band radiometry using an improved model approach

Global measurements of soil moisture, the key variables in the water cycle, are provided by spaceborne radiometer based on the long wavelength detection. As one potentially critical factor, topography will induce soil moisture retrieval error over mountain areas from space. To explore the mechanism of relief effects on L-band, the imitated landscapes are generated underlying Gaussian surfaces, and an improved microwave radiative transfer model to simulate relief effects is proposed. Based on the model, the significance of soil moisture and land surface temperature to relief effects in these terrain scenes are analyzed respectively, and the impact of topography on brightness temperature and soil moisture retrieval is predicted. It is shown that the maximum fractional error of soil moisture retrieval arisen by topography compared to soil moisture in the flat terrain at L band is 77.6%.