Rainfall Microstructural Analysis for Microwave Link Networks: Comparison at Equatorial and Subtropical Africa

Abstract

Abstract-The quest to understand the variation of rainfall microstructures at subtropical and equatorial regions is vital to rain attenuation studies. In this study, point rainfall datasets obtained at Butare (2 • 36 S, 29 • 44 E) and Durban (29 • 52 S, 30 • 58 E), are compared at the reflectivity threshold of 38 dBZ. Joss-Walvogel (JW) distrometer measurements collected from these two locations represent physical rainfall data from equatorial and subtropical climates respectively. The reflectivity threshold enables the classification of rainfall datasets into stratiform and convective (S-C) precipitation regimes. These thresholds, R th , at Durban and Butare are analysed based on three known rainfall microphysical parameters: rain rate, rainfall Drop Size Distribution (DSD) and radar reflectivity. The results from rain rate distributions at the both regions are similar for both stratiform and convective classes. However, the sampled DSDs indicate the dominance of larger rain droplets at Butare compared to observations at Durban, irrespective of the rain classes. In addition, it is found that the reflectivity distributions at both regions, under stratiform and convective conditions, are distinct in their probability profiles. The overall S-C analysis implied that the reflectivity and DSD profiles at both regions -result in significant variation of predicted specific attenuation -at microwave and millimeter band. In comparison with other global locations, it is affirmed that the S-C transition occurs globally at rain rates between 6 mm/h and 13 mm/h.

An Overview of Rainfall Fading Prediction Models for Satellite Links in Southern Africa

“…The present submission is a follow-up to earlier publications pertaining to rain attenuation and raindrop size distribution modelling in the sub-Tropical Africa, including Southern Africa and Equatorial Africa regions. These included the works of Afullo [3], Akuon and Afullo [4], Alonge and Afullo [5], Adetan and Afullo [6], and more recent publications by Sumbiri et al [7], Afolayan et al [8], Ahuna et al [9]. Further, we have the recent submissions by Ahuna et al on the rainstorm characterization [11], and the latest modified raindrop size modelling approach by Alonge [12], and the optimized raindrop size distribution by Sumbiri and Afullo [18].…”

Quantification of Rain Induced Artifacts on Digital Satellite Television Reception

“…Rainfall events are generally made up of two constituent precipitation types; the convective and the stratiform [12]. Convective precipitation is typically characterized with high rainfall intensity(~>20 mm/h), lasting over 803 803 803 803 a short period of time over a little coverage area, and accompanied by showers and thunderstorms [13]. On the other hand, stratiform precipitation (~<20 mm/h) is characterized with widespread and low rain rates, lasting for relatively longer period of time.…”

“…On the other hand, stratiform precipitation (~<20 mm/h) is characterized with widespread and low rain rates, lasting for relatively longer period of time. The stratiform rain event mainly accounts for drizzle and widespread rain [13,14].…”