Effective Path Length for Estimating Rain Attenuation Over an Earth‐Space Path Using Features of Stratiform and Convective Precipitation at a Tropical Location

The effective path length (LE) for the rain attenuation estimation over the Earth‐space path depends on rain cell size, rain rate, and rain height which in turn are determined by the types of rain. The present study examines the variation of LE based on the experimental measurements of Ku‐band attenuation and rain rate at a tropical location Kolkata (22°34′N, 88°22′E) in comparison with the ITU‐R. The study also utilizes measurements from a 24‐GHz micro rain Doppler radar to differentiate the precipitation types as stratiform and convective rain on the basis of the presence and absence of a melting layer. Power‐law models of LE in terms of rain rate are proposed for convective and stratiform types of rain. The investigation reveals the physical phenomena behind the variability of LE at low and high rain rates which are associated with stratiform and convective rain respectively. The proposed models provide a significantly better agreement with the experimental data compared to the ITU‐R model and also account for distinguishing features of two types of rain, thus giving a physical basis of the proposed model which is not reflected in the ITU‐R formulations.