Determination of Rain Rate from a Spaceborne Radar Using Measurements of Total Attenuation

Several experimental and theoretical studies have shown that path-integrated rain rates can be determined by means of a direct measurement of attenuation. For ground-based radars, this is done by measuring the backscattering cross section of a fixed target in the presence and absence of rain along the radar beam. A ratio of the two measurements yields a factor proportional to the attenuation from which the average rain rate can be deduced. In this paper, we extend the technique to spaceborne radars by choosing the ground as a reference target. The technique is also generalized so that both the average and range-profiled rain rates can be determined. The accuracies of the resulting estimates are evaluated for a narrow-beam radar located on a low earth-orbiting satellite.