Estimating surface soil moisture and soil roughness over semiarid areas from the use of the copolarization ratio

This paper presents a new method to retrieve soil moisture and roughness from ERS-1. Wind scatterometer (WSC) data measured over the HAPEX-Sahel area (semiarid environment). The retrieval algorithm makes full use of the multiangular acquisitions and the high temporal repetition of the measured backscattering coefficients. The vegetation contribution to the signal is taken into account through a first-order radiative transfer model. The soil moisture and roughness are subsequently retrieved, throughout the rainy season, using the copolarization ratio as expressed by Oh et al. [IEEE Transactions on Geoscience and Remote Sensing GE-30 (1992) 370–381]. The paper describes the data and the approach used, together with the results gained. A good sensitivity of the backscattering coefficient to soil moisture is obtained. The results are compared with data collected during the HAPEX-Sahel campaign.