0°C isotherm height distribution for Earth-space communication satellite links in Nigeria

Abstract

For an optimum performance of Earth-space satellite communication links, a number of meteorological parameters are needed to be considered along the Earth-space path for specific locations and the height of the 0°C isotherm (freezing level height) is among such parameters. Information regarding this parameter is always based on the recommendation of ITU-RP-839 in the form of contour maps. Since the meteorological parameters are location dependent, there is a need for the establishment of these parameters for specific locations. In addition, ITU-R model uses an yearly averaged constant rain height for the attenuation estimation, which may not be appropriate for tropical regions. In the present paper, the 0°C isotherm (ZDI) height has been established using two years of data collected on-board the precipitation radar of the Tropical Rain Measuring Mission (TRMM) satellite. The result shows the seasonal dependence of the 0°C isotherm height. It is observed, among other things, that the height is higher during the wet season as compared to the dry season. Rain induced attenuation at frequencies above 10 GHz is also estimated using the 0°C isotherm height derived for each of the locations over the elevation angle of the NIGCOMSAT-1R in Nigeria.