Ka‐band rain attenuation estimation using weather radar

Abstract

Weather radars have been routinely used for investigating propagation phenomena which affect satellite communication links. Weather radar returns can be used to estimate both attenuation and depolarization produced by hydrometeors. Some of the early radar measurements resulted in the discovery of high altitude ice particles as a potential source for depolarization and the development of models for the melting layer or the radar bright band. The radar return from precipitation particles is proportional to the number density of particles in the radar pulse volume. The reflectivity can be converted to an equivalent rain rate or signal attenuation through appropriate assumptions on the particle size distribution. If the radar is capable of measuring reflectivity in two orthogonal polarizations, the difference between the two reflectivity measurements is a direct estimate of the anisotropy of the particulate medium. Differential reflectivity can be used to detect regions containing highly non‐spherical particles such as the melting layer and high altitude ice particles. Results of an experiment involving a dual polarized radar to estimate Ka‐band path attenuation at a tropical location are presented.