A meteorological model for rain-induced cross polarization

Abstract

After a brief summary of the existing theory on microwave attenuation and cross polarization by rain and of the supporting experimental evidence, the paper gives a physical explanation of raindrop canting. It is shown that vertical windgradients are a cause of canting. A model for the dependence of windspeed on height is then employed to calculate actual values of canting angle and to investigate the dependence on windgradients, height above terrain, and the type of terrain. A generalization of the expressions for cross polarization as a function of raindrop canting angle is given, which allows actual cross polarization calculations to be made with the model. Results for sample cases on horizontal and slant paths are given to show the relative importance of various parameters.