Development of a Model for Estimation of Sunshine Hour Data for Different Regions of Uganda

The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (۱۹۸۴-۲۰۱۸) acquired from the National Aeronautics and Space Administration were used to compute the coefficients of the models which, yielded a coefficient of determination close to unity, signifying a good association between the sunshine hours (SH) and the associated indices. The models become distributed by introducing a longitudinal function of clearness index into the primary SHM developed. Moreover, the models were subjected to statistical validation using; mean absolute relative error (MARE), root mean square error (RMSE) and mean absolute percentage difference (APD). Consequently, the primary SHM showed strong agreement with the measured SH data in the three regions with the exception of the northern region with flawed on-station data. Also, validation of the models by; {MARE, RMSE, APD} for Eastern, Central and Western regions, yielding the following results; {۰.۰۷۸۸,۰.۵۴۴۱,۷.۸۷۷۸},{۰.۰۳۹۰,۰.۱۴۵۳,۳.۹۰۱۳} and {۰.۰۱۲۴,۰.۰۵۲۸,۱.۲۴۳۶}, respectively. The following maximum SH; ۱۱.۱۶, ۷.۸۷, ۹.۵۲, ۸.۸۶ and ۶.۰۶ h were recorded for Non-regional, Northern, Eastern, Central and Western regions, respectively. Further, comparative validation with redeveloped global SHM showed that the present model stands in all the regions, whereas the global models validated only in the Eastern region. This is attributed to the synergy of geographical and climatological indices against the global models only based on climatological index. The model results show the order of regional SH distribution; eastern>northern>central>western region. These results could be employed in solar power, exploitation and agrometeorology development. This study further recommends for adoption of the present model to non-equatorial regions upon redevelopment as a meaningful extension of this work.  

Keywords:

Model development , Model Estimation , Sunshine Hours , Uganda