The Effect of Solar Radiation Variability on Climate in Rwanda

The research assesses the effect of solar radiation variability on Rwanda’s climate. It aims to evaluate factors evaluating insolation, analyze the spatial and temporal distribution of solar radiation and climate then compare their variability with climate extreme indices. A quantitative study was conducted across all 30 districts using high-resolution monthly data. The study incorporated surface shortwave radiation from METEOSAT- SARAH, temperature data from ERA5 reanalysis, and climate indices such as diurnal temperature range (DTR) and number of events per day with at least 20mm of daily precipitation simulated by CMIP models. Statistical calculations were performed using Climate Data Operators, analysis and visualization were done with Grid Analysis and Display System software. The period from 1983 to 2015 was analyzed. Maximum surface shortwave radiation (SSR) values were found in the eastern province while minimum values were found in the north. The maximum temperature was 31.2o C in Nyagatare, and the minimum value was 27.4o C in Nyabihu. (DTR) was the highest in most parts of Rwanda during June-August. The maximum number of events per day with at least 20mm of daily precipitation (R20mm) was 190 in the Rutsiro District in 2009. The study revealed significant correlations between solar radiations and climate extremes. SSR was positively correlated to temperature and negatively correlated to DTR and R20mm indicating its impact on Rwanda’s climate. Keywords: Solar radiation variability, climate, climate extreme indices, correlation, Rwanda