MELTING LAYER CHARACTERIZATION OVER AKURE, SOUTH WEST NIGERIA: IMPLICATIONS FOR RAIN ATTENUATION ESTIMATION

Abstract

Hydrometeors pose a serious threat to satellite systems operating at frequencies above 10 GHz. The design of line of sight links is usually based on the ITU-R models, which are often inadequate for tropical region. ITU-R model uses a yearly averaged constant rain height for the prediction of specific attenuation, which may not be valid for tropical locations. This study reports the investigation of rain height based on Micro Rain Radar measurements at a tropical location, Akure, Nigeria. The main objective of this research work is to give a clearer view of melting layer and the bright band and their contribution to signal attenuation in a tropical region like Akure. This determination includes the evaluation of the rain height and zero degree isotherm height. To achieve this objective fully, the raw data measured have been sorted out, filtered, plotted and analyzed. Radar observable parameters have been plotted against the corresponding heights, and their boundaries have been determined according to the enhancement and transition of radar parameters. Results obtained suggest a possible modification in the rain attenuation model taking into account the melting layer height variation with the season and rain rate. The results give an acceptable correlation with the International Telecommunication Union- Radio communication sector (ITU-R) recommendations and a good one with the results that are obtained from the Micro Rain Radar and the characteristics of the melting layer in Akure.