Spaceborne altimetry and scatterometry backscattering coefficients at C- and Ku-band over West Africa

This study presents a comprehensive comparison of radar signatures acquired over West-Africa at both Ku- and C- bands using nadir-looking altimeters and side-looking scatterometers that covers the major bioclimatic zones, soil and vegetation types encountered in this region. The backscattering coefficients time series measured by both radar instruments are generated over regional transects and local sites. Meridian transects from the wet tropics to the arid regions of the Sahara desert point out the spatial and temporal changes of the radar response over the West-African bioclimatic gradient in terms of surface roughness, land cover and soil wetness. Nadir looking altimetry appears more sensitive to variations of surface soil moisture than side-looking scatterometry at both C- and Ku-bands. In contrast, the impact of vegetation on the backscattered signals is found to be lower for nadir-looking instruments compared to side-looking ones.