Heterogeneous Trends of Precipitation Extremes in Recent Two Decades over East Africa

East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged droughts. However, systematic regional assessment of precipitation extremes across seasons has received little attention, and most previous studies of precipitation extremes have employed many indices and sparse gauge observations giving marginalized details. In this study, we use three precipitation extreme indices to examine the intensity of the highest single-day rainfall record (rx1day), prevalence of very heavy rainfalls (r30mm), and persistence of successive wet days (cwd) at both annual and seasonal scales over recent two decades (1998-2018) based on the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis data. The results show that the most intensive and frequent precipitation extremes are noticeable from January to May across the areas extending from Madagascar to the Tanzanian coastal zone. These areas also exhibit patches of significant increasing trends in frequency, duration, and intensity of precipitation extremes annually and seasonally. However, significant declines in frequency and intensity of precipitation extremes are observed from western Ethiopia to Congo-Uganda, especially in June-September. The October-December season witnesses higher interannual variability amounting to overall weak and less significant trends. Further subregional assessment shows overall declining intensity and frequency of precipitation extremes in northern part of the study areas. Mean wetness duration increased, with persistence of moderate wet days and slight reduction of severe events. This study unveils higher susceptibility of the East African region to the widely observed hotspots of precipitation extremes posing threats to food security, water resource, and human well-being. The region should consider upscaling irrigation schemes in addition to planning resilient and supportive infrastructures to withstand the upsurging precipitation extremes, especially along the coastal zone.