A Class of Single- and Dual-Frequency Algorithms for Rain-Rate Profiling from a Spaceborne Radar. Pad I: Principle and Tests from Numerical Simulations

Abstract A class of single- and dual-frequency algorithms that can be used to infer rain-rate profile from a downward-looking spaceborne radar operating at attenuating frequencies is presented. These algorithms rely on use of power-law relations between the radar reflectivity factor Z and the specific attenuation coefficient k. First, they provide estimates of attenuation-related parameters such as the range-profiled specific attenuation coefficient or partial range-averaged specific attenuation coefficients. Then, the corresponding rain rate R range profile can be derived by using a relevant R-k relationship. Profiling may be performed either from the radar or from the surface. The basic purpose of the various algorithms is to correct for several types of range-free scaling errors that may alleviate, for example, requirements on radar calibration and/or storm modeling (cloud, melting layer). Corrections are performed by using an additional measurement of the surface echo, an additional hypothesis (such a...