%0 Journal Article
%T Rain Height Statistics Based on 0¡ãC Isotherm Height Using TRMM Precipitation Data for Earth-Space Satellite Links in Nigeria
%A Joseph Sunday Ojo
%J ISRN Atmospheric Sciences
%D 2014
%R 10.1155/2014/798289
%X In the prediction of attenuation due to precipitation related phenomena, the 0¡ãC isotherm height plays a vital role. In this paper, 2 years of precipitation data obtained from the Tropical Rain Measuring Mission (TRMM) satellite had been analyzed to establish the distribution of rain height based on 0¡ãC isotherm heights over six locations in Nigeria. Probability of exceedance of rain heights in each of the locations was compared between the two seasons in Nigeria. Rain heights distribution was also compared with the ITU-R P.839 recommendation. The overall results show seasonal, rainfall type¡¯s dependence and overestimation of the rain height predicted by the ITU for Nigeria. 1. Introduction As the satellite communication link continues to expand its bandwidths for higher data rates, among others, system performances can be marred by the increased propagation challenges at these higher frequency ranges. Rain induced attenuation of microwaves poses a serious challenge to system/signal availability at frequencies above 10£¿GHz. For good system design, the designer must provide adequate fade margins to ensure system availability. There are a number of propagation mechanisms affecting Earth-space satellite communications that are a major concern in the system design. These include gaseous attenuation, cloud and fog attenuation, and rain and ice attenuation [1, 2]. However, rain-induced attenuation has been identified to cause the most serious degradation to system performances of both terrestrial and satellite links operating at frequencies above 10£¿GHz [3¨C5]. In order to estimate the level of the degradation, most researchers normally used prediction methods when actual measurements are not available. Among the meteorological parameters needed for prediction method is the annual average of the 0¡ãC isotherm height. This 0¡ãC isotherm height is the height in the stratiform type of rain where the frozen hydrometeors begin to change state into liquid rain due to temperature difference [3, 6]. The ITU-R [7] gave a global map of 0¡ãC isotherm height above mean sea level (km) on a resolution of 1.5¡ã by 1.5¡ã in both latitude and longitude to be used in regions of the world where no location specific information is available. However, study revealed that this height strongly depends on local weather [8, 9]. In this paper, the annual average, year-to-year variability, probability distribution levels, and seasonal variation of 0¡ãC isotherm height derived from TRMM-PR data for some locations in Nigeria are presented. 2. Climatology of Nigeria and Source of Data Nigeria
%U http://www.hindawi.com/journals/isrn.atmospheric.sciences/2014/798289/