Effect of Tropospheric Propagation on Ka band Spaceborne Radar Altimeters

The next generation of spaceborne radar altimeter such as AltiKa or SWOT will make use of the Ka band instead of the formerly used S, C and Ku bands in order to get a better spatial resolution. As a consequence the signal will be more significantly attenuated during its way through the troposphere particularly if it rains or if there are liquid clouds. In addition, the non uniformity of the tropospheric attenuation inside the radar beam footprint due to the non homogeneity of the rain and clouds fields can distort the shape of the returned echo. It can thus lead to a bias of the retrieved geophysical parameters if it is not properly identified. The present work has two different purposes, namely the estimation of the attenuation statistics undergone by Ka-band altimetric signal and the presentation of a methodology to evaluate echoes distortion by the simulation of tropospheric attenuation fields.