A Radar Attenuation-Reflectivity Technique for the Remote Measurement of Drop-Size Distributions of Rain

Abstract

The two parameters of the Marshall-Palmer drop-size distribution for rains are developed as functions of measurements of dual-wavelength relative attenuation and single-wavelength equivalent reflectivity. Accurate dual-wavelength attenuation measurements are shown to require similar drop-size distributions at the extremes of the measurement volume under consideration, require scattering at the extremes in the Rayleigh region only, or require the ratio of the Mie to Rayleigh scatters at the extremes to be the same. Typical rains, wherein these requirements are not fully met, were considered. Acceptable path attenuation errors are shown to exist for rainfall rates from 0.4 to 20 millimeters per hour for a K?X hand system and from 2 to 100 millimeters per hour for an X?S band system. If advanced instrumentation is employed, this technique could improve the rainfall rate estimates by weather radar, and support basic meteorological research as well.