Comparisons between years of below average rainfall over West Africa,
sea-surface temperatures (SST) over the Atlantic Ocean and the world o
cean, and latitudinal positions of the Inter Tropical Convergence Zone
(ITCZ) over the Atlantic Ocean show that the relationships depend mai
nly on the rainfall anomaly patterns. The well-known SST dipole (cold
northern ocean and warm equatorial and southern ocean) is only apparen
t during those August months with below average Sudano-Sahelian rainfa
ll and above average Guinean rainfall (rainfall type'-/+') and an abno
rmal southward position of the ITCZ. In contrast, those August months
that experience rainfall deficits over the whole of West Africa (rainf
all type '-/-') are associated with warm SST anomalies over the easter
n Pacific Ocean, cold persistant SST anomalies over the equatorial Atl
antic Ocean and a more northward position of the ITCZ. Those patterns
first appear in northern spring before the Sahelian rainy season. The
composite SST differences for the '-/+' and '-/-' rainfall types compu
ted with August or July-September amounts have a good resemblance with
each other. Comparison of results related to the reverse July-Septemb
er rainfall patterns (the '+ / -' and '+ / +' patterns) during the 195
0s shows that the SST anomalies were globally colder when, on average,
the Sahelian rainy seasons experienced significant excesses while the
Guinean little dry seasons were more marked.