Inter annual variability of medium level circulation and Its association with seasonal rainfall over equatorial East Africa.
Abstract
This study was an attempt to explore the role of atmospheric circulation and its predictive
association or linkage with seasonal rainfall over Equatorial Eat Africa. The data used in
the study included the NCEP/NCAR reanalysis wind data, the CRU global rainfall data
and station rainfall data for the three East African countries comprising Kenya, Uganda
and Tanzania. The study period extended from 1961-1998. In order to assess the
association between atmospheric circulation and the seasonal rainfall over the domain of
this study, statistical methods were adopted. These included quality control,
standardization of anomaly indices and correlation analysis.
Results from the quality control tests indicated that the data used in the study were of
good quality. The standardized rainfall data were used to compare the year to year
rainfall patterns. It was evident from the normalized rainfall indices that occurrences of
droughts and floods are common over East Africa and that some of the extreme rainfall
events coincide with certain phases of the zonal wind, the u component. The correlation
between the u wind component and the seasonal rainfall index during the short rainfall
season over the area 40oE-50oE; 5~-5°S was significant.
It was concluded from the study that there is a possible linkage between the OND rainfall
index and the u wind component over the location 40oE-50oE; 5~-5°S within the area of
study. Such information will help improve monitoring, prediction and early warning of
extreme rainfall events over the region of study. It was also concluded from the
predictive potentials of the study that the month of January could be used to predict the
long rainfall season. However the short rainfall season did not show any predictive
potential.
Citation
Master of Science in MeteorologySponsorhip
University of NairobiPublisher
Department of Meteorology University of Nairobi