Rainfall Variability in Africa
Abstract
Time series' of annual rainfall for 69 stations in Africa we~e analyzed for trends an? p~riodicities.
Trend analysis showed that most of the annual series indicate some forr~s ~f ?sclllatlons .. rather
than any particular trend. Use of binomial coefficients to smooth the senes m~lc~ted po.sltl.ve or
negative trends in recent years in 20 series, but only four of these were. statlstl~al~y slgmfi.ca?t
judging by the Spearman rank correlation test. These four stations were geographically distributed within
those showing no significant trends. . .
Assuming the generating process to be purely random, the prominent cycles revealed by the spectral
analysis were 2.0-2.5 years and 2.7-3.3 years. In general, the larger observed cycles (3.5-4.4 years,
5.0 years, 6.0-6.5 years, 7.0-8.0 years and 10.0 years) were weak at the 0.05 significance level.
Citation
Monthly Weather Review, Vol.107, No. 9, September 1979Publisher
Department of Meteorology, University of Nairobi
Description
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