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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]

The tropical Andes of southern Peru and northern Bolivia have several major mountain summits suitable for ice core paleoclimatic investigations. However, incomplete understanding of the controls on the isotopic (δD, δ18O) composition of precipitation and a paucity of field observations in this region continue to limit ice-core-based paleoclimate reconstructions. This study examines four years of daily observations of δD and δ18O in precipitation from a citizen scientist network on the northeastern margin of the Altiplano, to identify controls on the subseasonal spatiotemporal variability in δ18O during the wet season (November–April). These data provide new insights into modern δ18O variability at high spatial and temporal scales. We identify a regionally coherent subseasonal signal in precipitation δ18O featuring alternating periods of high and low δ18O of 9–27-day duration. This signal reflects variability in precipitation delivery driven by synoptic conditions and closely relates to variations in the strength of the South American low-level jet and moisture availability over the study area. The annual layer of snowpack on the Quelccaya Ice Cap observed in the subsequent dry season retains this subseasonal signal, allowing the development of a snow-pit age model based on precipitation δ18O measurements, and demonstrating how synoptic variability is transmitted from the atmosphere to mountaintop snowpacks along the Altiplano's eastern margin. This result improves our understanding of the hydrometeorological processes governing δ18O and δD in tropical Andean precipitation and has implications for improving paleoclimate reconstructions from tropical Andean ice cores and other paleoclimate records. [ABSTRACT FROM AUTHOR]