Qualitative rainfall prediction models for central and southern Sudan using El Niño–southern oscillation and Indian Ocean sea surface temperature Indices

Abstract In this study, the influences of El Niño–southern oscillation (ENSO) and the Indian Ocean sea surface temperature (SST) on rainfall variability in the central and the southern regions of Sudan are investigated. The investigation is conducted using 49 years of data from 12 rainfall stations. The results show that the driest years are associated with warm ENSO and Indian Ocean SST conditions. In the two regions, the correlation of the annual rainfall with the Indian Ocean SST is found to be relatively higher than that with the ENSO SST, with the Indian Ocean SST having stronger influences in the central region. The multiple correlation results indicate that both of the ENSO and Indian Ocean SSTs explain about 34% of the annual rainfall variability in the central region and 21% in the southern region. Two types of qualitative rainfall prediction model are developed for each region. One type uses the ENSO SST as input and the other uses the Indian Ocean SST. The verification results show that the Indian Ocean SST model is better than the ENSO SST model. Copyright © 2002 Royal Meteorological Society.