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In semi‐arid environments, rainfall‐driven soil moisture fluctuations exert a strong influence on surface turbulent fluxes. Intraseasonal rainfall variability can therefore impact low‐level atmospheric temperatures and influence regional circulations. Using satellite observations and an atmospheric reanalysis, we investigate whether rainfall variability induced by the Madden–Julian oscillation (MJO) triggers land–atmosphere feedbacks across East Africa. We identify that surface fluxes during the East African wet seasons (March–May and October–December) are sensitive to MJO‐induced precipitation variations across low‐lying regions of South Sudan and highland regions of Uganda and southwest Kenya. For example, during MJO phases 6 to 8, when rainfall is suppressed, surface temperatures and sensible heat fluxes increase, whilst evapotranspiration decreases. Spatial variations in the surface flux response to rainfall variability feed back onto the atmosphere through amplifying MJO‐associated pressure anomalies. During dry MJO events for instance, surface warming across the exit region of the Turkana channel increases the low‐tropospheric along‐channel pressure gradient and intensifies the Turkana jet. We conclude that average surface‐driven temperature fluctuations during a single day are responsible for approximately 12% of MJO‐associated variability of the Turkana jet speed. However, we expect that the accumulation of heat over multiple days to the west of the East African Highlands further amplifies anomalies in the pressure gradient and jet intensity. Modelling experiments are required to quantify the accumulated impact of the surface forcing. Surface‐driven Turkana jet variations influence the East African moisture budget and affect the intensity and inland propagation of coastal convection. Not only is this the first study to investigate the importance of intraseasonal land–atmosphere feedbacks across East Africa, but it is also the first to show that Turkana jet characteristics are partly driven by surface conditions. This work motivates an investigation into whether subseasonal forecast models fully harness the predictability from surface‐induced jet variations. [ABSTRACT FROM AUTHOR]

This study analyzes warm spells in the dry season over the East African plateau. Lake levels were observed to decline in the period July 2004 to January 2007. The warmest spell was identified using maximum temperature and satellite outgoing longwave radiation (OLR) observations averaged over Uganda: 20-22 Feb 2005. Meteorological conditions in that case were dominated by a surge of the NE monsoon from the Arabian Sea toward East Africa. Subsiding air induced daytime land surface temperatures >55 °C. Dry easterly winds swept across Uganda, and the vegetation fraction dropped >10% in 1 month. At the seasonal scale, the NE monsoon intensity over the Arabian Sea correlated with indices of desiccation over the White Nile basin. In the annual cycle, sensible heat flux follows potential evaporation, reaching −4.5 mm/day in February. Coupled Model Intercomparison Project Phase 5 (CMIP5) model projections favor a long-term weakening of the NE monsoon and a northward migration of the equatorial trough over the west Indian Ocean in Dec-Mar season. Although maximum temperatures are projected to rise +2 °C by the end of the 21st century, the length of the dry season could shrink, thus maintaining the water balance near current levels. [ABSTRACT FROM AUTHOR]

This study investigates the variability of extreme rainfall (temperature) events in the twenty-first century based on 18 (24)-member multimodel simulations of models participating in phase 5 of the Couple Model Intercomparison Project (CMIP5). The study employed extreme indices defined by the WMO's Experts Team on Climate Change Detection Indices, under two radiative forcing scenarios: RCP4.5 and RCP8.5. Two 30-year time periods, mid- (2021-2050) and end (2071-2100) of the twenty-first century, are considered for investigation of extremes, relative to the baseline period (1961-1990). Mann-Kendall test statistic and Sen's slope estimator are used to investigate trend. Temperature shows a remarkable increase with an increase in radiative forcing. A sharp augmentation in temperature is projected towards the end of the twenty-first century. There will be almost zero cool days and cold nights by the end of the century. Very wet and extremely very wet days increase, especially over Uganda and western Kenya. Variation in maximum 1-day precipitation (R × 1 day) and maximum 5-day precipitation amount shows a remarkable increase in variance towards the end of the twenty-first century. Although the results are based on relatively coarse resolution data, they give likely conditions that can be utilized in long-term planning and be relied on in advanced studies. [ABSTRACT FROM AUTHOR]