Use of the Indian ocean dipole indices as a predictor of east African rainfall anomalies
Abstract
This study was devoted to the improvement of prediction skill of east African
seasonal rainfall through the use of improved knowledge of the teleconnections between
Indian Ocean Dipole (laD) evolution phases and the East African rainfall variability. The
specific objectives of the study included determination of teleconnections between east
African seasonal rainfall extremes and space-time evolutions of the various laD phases;
investigating the physical mechanisms of the teleconnections; and determination of the
predictability potentials of laD indices. The data sets used in this study include rainfall
data for the three East African countries (Kenya, Uganda and Tanzania), global sea
surface temperatures (SSTs) and NCARINCEP reanalysis data. The study period
extended from 1950 to 2003.
To achieve the objectives of the study, statistical and dynamical methods were
adopted in this study. The statistical methods used in the study include standardization of
anomaly indices; together with correlation, regression and composite analyses. Spacetime
characteristics of a series of dynamical parameters were investigated using products
from ECHAM4.5 general circulation model (GCM) and the NCEPINCAR reanalysis to
ascertain the physical reality of the laD-seasonal rainfall linkages derived from the
statistical approaches.
The results of the study demonstrated that some of the extreme rainfall conditions
over Eastern African hiring' the short rainfall season were associated with positive and
negative laD phases. Such information will help to improve monitoring, prediction and
early warning of extreme rainfall events over east Africa, reduce the vulnerability, and
improve the resilience of the society of the region to negative impacts of extreme rainfall
events that are common in the region.
Citation
Master of Science in MeteorologySponsorhip
University of NairobiPublisher
Department of Meteorology, University of Nairobi