ITCZ Cloud Clusters in Association with African Easterly Waves during Summer Seasons of El Nino and La Nina Years

El- Nino and La- Nina conditions have been reported during the years of 1997 and 1998 respectively. Composite anomalies of sea surface temperature SST and surface precipitation rate of NCEP/ NCAR reanalysis data set for July and August months of 1997 and 1998 have been investigated through this study. Day-to-day variations in conditions, location, width and activity of the Intertropical Convergence Zone, ITCZ, cloud band have been investigated over Africa using longitude time sections, constructed from successive daily METEOSAT images during the same period. The ITCZ cloud clusters had been observed more active and covered larger areas during July and August months of 1998 compared with those observed during 1997. Westward propagating cloud lines, constructed from successive images of individual cloud clusters, could be detected over West Africa and the Atlantic Ocean. During 1998, the cloud lines could be observed more active, well defined and more regular than those observed during 1997. The cloud lines showed significant characteristics similar to those of the African easterly waves. Over Eastern Tropical Africa, the ITCZ cloud clusters appeared almost stationary, only meridional oscillations and variations in shape and intensity could be observed. However, one may suggest that disturbances of the ITCZ cloud clusters can be considered as the visual evidence of easterly waves over Africa.