Attenuation correction algorithms for precipitating area with poly-disperse small spheroid raindrops

摘要

The relationship between attenuation coefficient, k, and radar reflectivity factor, Z, as well as that between Z and rainfall rate, I, is influenced by the shape of precipitating raindrops and the orientation of their rotatory axes respect to the polarization direction of the incident radar wave. Provided that the orientation of rotatory axes of poly-disperse small spheroid particles is known, correctable thickness of radar echo for attenuation depends mainly on rainfall rate. The heavier the rainfall rate, the thinner the correctable thickness. For an 80 mm/hour precipitation uniformly distributed along a radial direction, correctable thickness of radar echo is more than 120 km for 5.6 cm wavelength and about 50 km for 3.2 cm if correction algorithm R2 or R3 is used. Orientation information is critically important during attenuation correction. Right k-Z relationship must be coupled with right orientation status.