Trend of rainfall in East Africa
Abstract
Trends of rainfall in East Africa during the period 1922-1975 are examined
using two independent approaches. namely the graphical and statistical
methods. Under the graphical method the original and smoothed rainfall
series were displayed visually on a graph. while the Spearman rank
correlation test and the analysis of variance approach were employed in
the statistical approach. The data used included the monthly. seasonal and
annual rainfall records of about 100 stations during the period 1922-1975.
The results of the study indicate significant trends of annual rainfall at
nine stations when the Spearman rank correlation test was used. The
smoothed graphs indicated similar tendencies at these stations during the
period of study. The use of analysis of variance technique. however.
indicated no significant difference between long-term averages and the
averages of some standard periods at six of the nine stations. The only
three stations where significant rainfall trends were indicated with both
methods were Lodwar, Wajir and Magadi. All methods indicated an
increasing annual rainfall tendency at these stations during the period of
study. The results from the monthly. seasonal and regional rainfall records
revealed no significant trends on the regionally averaged annual rainfall
records. or on the monthly and dry season records. The wet seasons had
characteristics close to those of the annual series.
Citation
Kenya Journal of Science and Technology (A) (1981) 2: 83-90Publisher
Department of Meteorology, University of Nairobi. Nairobi. Kenya