Abstract
In this study, we use the queuing theory approach is applied to investigate the attributes and behavior of intense rain storms along an earth-space link over Durban, South Africa (2952’S, 3058’E), a sub-tropical climate. Thereafter, a comparison is made with results obtained in a related study in Jimma, Ethiopia (7.6667N, 36.8333E), which is a tropical climatic region. Verification of the best fit distribution is done through the application of the root mean square error (RMSE) and CHI squared statistics. Results of these analysis tools confirm the suitability of the proposed distributions with RMSE error margin in the range 0.0024 to 0.0128, and a 𝜒2 statistics value of 0.4070. The spike service time for such rain storms is found to follow Erlang-k distribution in both regions of South Africa and Ethiopia as opposed to earlier determined exponential distribution. In addition, the analysis shows that there exists a power law relationship between the rain spike maximum rain rate and its diameter. Furthermore, the Markov chain technique is employed to determine the occurrence behavior of shower and storm rainfall regimes, and their contributions to rain attenuation over a slant path radio link. Detailed analysis shows that the R0.01 parameter arising over the years with these intense storms is considerably larger than that proposed by ITU-R Recommendation for the region of study.