West-central Uganda, a biodiversity hotspot on the eastern edge of
central equatorial Africa (CEA), is a region coping with balancing food
security needs of a rapidly growing human population dependent on
subsistence agriculture with the conservation of critically endangered
species. Documenting and understanding rainfall trends is thus of critical
importance in west-central Uganda, but sparse information exists on
rainfall trends in CEA during the past several decades. The recently
created African Rainfall Climatology version 2 (ARC2) dataset has been
shown to perform satisfactorily at identifying rainfall days and
estimating seasonal rainfall totals in west-central Uganda. Therefore, we
use ARC2 data to assess rainfall trends in west-central Uganda and other
parts of equatorial Africa from 1983–2012. The core variables examined
were three-month rainfall variables for west-central Uganda, and annual
rainfall variables and seasonal rainfall totals for a transect that
extended from northwestern Democratic Republic of the Congo to southern
Somalia. Significant decreases in rainfall in west-central Uganda occurred
for multiple three-month periods centered on boreal summer, and rainfall
associated with the two growing seasons decreased by 20 % from 1983–2012.
The drying trend in west-central Uganda extended westward into the Congo
rainforest. Rainfall in CEA was significantly correlated with the Atlantic
Multidecadal Oscillation (AMO) at the annual scale and during boreal
summer and autumn. Two other possible causes of the decreasing rainfall in
CEA besides North Atlantic Ocean sea-surface temperatures (e.g., AMO), are
the warming of the Indian Ocean and increasing concentrations of
carbonaceous aerosols over tropical Africa from biomass burning. Copyright Springer Science+Business Media Dordrecht 2014
