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Long‐term trends in equatorial African rainfall have proven difficult to determine because of a dearth in ground‐measured rainfall data. Multiple, satellite‐based products now provide daily rainfall estimates from 1983 to the present at relatively fine spatial resolutions, but in order to assess trends in rainfall, they must be validated alongside ground‐based measurements. The purpose of this paper is twofold: (a) to assess the accuracy of four rainfall products covering the past several decades in western Uganda; and (b) to ascertain recent, multi‐decadal trends in annual rainfall for the region. The four products are African Rainfall Climatology Version 2 (ARC2), Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record (PERSIANN‐CDR), and TAMSAT African Rainfall Climatology And Timeseries (TARCAT). The bias and accuracy of 10‐day, monthly, and seasonal rainfall totals of the four products were assessed using approximately 10 years of data from 10 rain gauges. The homogeneity of the products over multiple time periods was assessed using change‐point analysis. The accuracy of the four products increased with an increase in temporal scale, and CHIRPS was the only product that could be considered sufficiently accurate at estimating seasonal rainfall totals throughout most of the region. TARCAT tended to underestimate totals, and ARC2 and PERSIANN were in general the least accurate products. Only annual rainfall estimates from CHIRPS and TARCAT were significantly correlated with ground‐measured rainfall totals. TARCAT was the most homogeneous product, while ARC2, CHIRPS, and PERSIANN had significant negative change points that caused a drying bias over the 1983–2016 period. After adjusting the satellite‐based rainfall estimates based on the timing and magnitude of the change points, annual rainfall totals derived from all four products indicated that western Uganda experienced significantly increasing rainfall from 1983 to 2016. [ABSTRACT FROM AUTHOR]

Smallholder farmers and livestock keepers in sub-Saharan Africa are on the frontlines of climate variability and change. Yet, in many regions, a paucity of weather and climate data has prevented rigorous assessment of recent climate trends and their causes, thereby limiting the effectiveness of forecasts and other services for climate adaptation. In rainfed systems, farmer perceptions of changing rainfall and weather patterns are important precursors for annual cropping decisions. Here, we propose that combining such farmer perceptions of trends in seasonal rainfall with satellite-based rainfall estimates and climate station data can reduce uncertainties regarding regional climatic trends. In western Uganda, a rural and climatically complex transition zone between eastern and central equatorial Africa, data from 980 smallholder households suggest distinct changes in seasonal bimodal rainfall over recent decades, specifically wetter rainy seasons and drier dry seasons. Data from three satellite-based rainfall products beginning in 1983 largely corroborate respondent perceptions over the last 10–20 years, particularly in the southernmost sites near Queen Elizabeth National Park. In addition, combining all three information sources suggests an increasing trend in annual rainfall, most prominently in the north near Murchison Falls National Park over the past two decades; this runs counter to recent research asserting the presence of a drying trend in the region. Our study is unique in evaluating and cross-validating these multiple data sources to identify climatic change affecting people in a poorly understood region, while providing insights into regional-scale climate controls. [ABSTRACT FROM AUTHOR]

Abstract: The climate of tropical Africa transitioned from an interval of pronounced, orbitally-paced megadroughts to more humid and stable conditions approximately 70,000years ago (Scholz et al., 2007). The regional atmospheric circulation patterns that accompanied these climatic changes, however, are unclear due to a paucity of continental paleoclimate records from tropical Africa extending into the last interglacial. We present a new 140-kyr record of the deuterium/hydrogen isotopic ratio of terrestrial leaf waxes (δDwax) from drill cores from Lake Malawi, southeast Africa, that spans this important climatic transition. δDwax shifts from highly variable and relatively D-depleted to more stable and D-enriched around 56ka, contemporary with the onset of more humid conditions in the region. Moisture source and transport history dominate the δDwax signal at Lake Malawi, with local rainfall amount playing a secondary role for much of the paleorecord. Analysis of modern moisture sources for Lake Malawi suggests that D-depletion of waxes during the megadroughts may have been caused by an enhanced contribution of the drier, D-depleted air mass currently located in central southern Africa to the Lake Malawi catchment. This D-depleted air mass is associated with the descending limb of the Hadley cell, which implies significant changes in the Hadley circulation during the megadroughts and related changes in the position of the Intertropical Convergence Zone over Africa. These findings demonstrate the ability of δDwax to serve as an atmospheric tracer when used in conjunction with additional proxy records for moisture balance, and elucidate potential mechanisms for pronounced hydrological change in southeast Africa during the late Pleistocene. [Copyright &y& Elsevier]