Observational evidence of climate change on extreme events over East Africa

Abstract

Examination of trend patterns of rainfall and temperature extremes over East Africa (EA) was based on graphical, regression and Mann-Kendall test approaches, while perturbations of rainfall, sunspot activity (SA) and southern oscillation index (SOI) extremes were computed using moving average methods. Annual total rainfall generally decreased with heavy and extreme precipitation rates confined within short spells during wet days. Observed maximum temperature extremes increased while minimum temperature extremes decreased with a statistically significant rise in the number of hot days and warm nights and a decrease in number of cool days and cold nights. However, space-time pattern of observed changes were not well organized. Perturbations of rainfall, SA and SOI indicated that extreme values were changing with increasing frequency and magnitude. Similarities in observed rainfall over EA illustrated the existence of homogeneous zones of climate change clustered as either coastal (with SA dominant), lake Victoria (unique to both SA and SOI), dry continental (SOI) or wet continental areas (both SA and SOI dominant).