Characterization of Historical Seasonal and Annual Rainfall and Temperature Trends in Selected Climatological Homogenous Rainfall Zones of Uganda
There is general lack of scientific consensus on the trend and distribution of annual and seasonal rainfall and temperature in Uganda. This study used both observational and AgMerra rainfall and temperature data for the period 1980-2010 to characterize the trend and variability in seasonal and annual rainfall, maximum and minimum temperatures across 12 different rainfall homogenous zones (K, H, ME, L, J, F, MW, D, E, A1, A2, and I) of Uganda. Trends analysis was done using regression method, while coefficient of variation and ANOVA techniques were used to analyze variability. The results show statistically significant increasing trends (P ≤ 0.05) in annual rainfall amount in zone A1 and a declining trend for zone K (P<0.05). Zones ME and H did not show any significant seasonal trend; while MAM rainfall increased for Zones A1 and F, and declined for J and K. In zone E, the SON rainfall linearly increased with time. The seasonal rainfall amount change was only significantly reflected in the annual rainfall amount of zone A1 and K. The annual rainfall amount increased significantly for A1 and declined for Zone K; respectively. The CV of all the studied rainfall zones showed significant trend over the years (P<0.05). It increased for A1, MW, H, L and I zones, declined for zone D and followed a quadratic trend with a maximum for F, K and ME. Seasonal Tmax and Tmin increased linearly for both seasons for I and D. For A1 and L only Tmax for SON did not show significant variation (P<0.05). For zone L, the MAM Tmin significantly increased gradually for both seasons; while for zone E, Tmax increased only for MAM. The annual Tmax and Tmin increased linearly with time for zone A1, A2, I and L. For zone K, E and F, only Tmax increased linearly with time; while for zone D only Tmin had significantly increased with time.
