OBTAINING RAINDROP SIZE MODEL USING METHOD OF MOMENT AND ITS APPLICATIONS FOR SOUTH AFRICA RADIO SYSTEMS

Abstract

In this paper, the Raindrop Size Distribution (DSD) modeling and analysis are presented. Drop sizes are classifled into difierent rain types, namely: drizzle, widespread, shower and thunderstorm. The gamma and Lognormal distribution models are employed using the method of moments estimator, considering the third, fourth and sixth order moments. The results are compared with the existing raindrop size distribution models such as the three parameter lognormal distribution proposed by Ajayi and his colleagues and Singapore's modifled gamma and Lognormal models. This is then followed by the implementation of the proposed raindrop size distribution models on the computation of the speciflc rain attenuation. Finally, the paper suggests a suitable raindrop size distribution model for the region with its expressions. The proposed models are very useful for the determination of rain attenuation for terrestrial and satellite systems.