An analysis of recent rainfall conditions in eastern Africa

摘要

This article examines recent rainfall conditions in two sectors of eastern Africa, the summer rainfall region and the equatorial rainfall region with rainy seasons in the boreal spring and boreal autumn. The analysis covers the years 1998-2014 and is carried out using TRMM 3B43 Version 7 rainfall estimates. In both regions, extensive periods of anomalously low rainfall and prolonged drought have prevailed since roughly 2008. Prior to that time, only three periods of drought are noteworthy 1998/1999, 2000, and 2005. The post-2008 drought conditions were interrupted by floods in both regions in February 2010 and in several years in the equatorial region. This rapid alternation between extremes creates additional hardships on the population. Two notable results emerge from this analysis. One is the tendency for similar trends in interannual variability in both regions, despite vastly different rainfall regimes. The other is the persistence of recent droughts through several rainy seasons. The implication of these results is that one or more factors in interannual variability is operative in all seasons. This could account for the common trends in the equatorial and summer rainfall regions.