Open AccessWest African Monsoon Dynamics and Eastern Equatorial Atlantic and Pacific SST Anomalies (1970–88)
Author(s) -
Serge Janicot,
Ali Harzallah,
Bernard Fontaine,
Vincent Moron
Publication year - 1998
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/1520-0442-11.8.1874
Subject(s) - intertropical convergence zone , climatology , monsoon , geology , anomaly (physics) , walker circulation , tropical atlantic , el niño southern oscillation , atlantic equatorial mode , oceanography , sea surface temperature , atlantic multidecadal oscillation , geography , precipitation , physics , condensed matter physics , meteorology
The Laboratoire de Météorologie Dynamique atmospheric GCM is used to investigate relationships between West African monsoon dynamics and SST anomalies in the eastern equatorial Atlantic and Pacific for the period 1970–88. Positive SST anomalies in the eastern equatorial Pacific, mainly associated with a larger east–west divergent circulation over the tropical Atlantic, are found to coincide with negative rainfall anomalies over West Africa. This is the case for the composite ENSO warm episodes of 1972, 1976, 1982, and 1983. By contrast, positive SST anomalies in the eastern equatorial Atlantic are accompanied by a southward shift of the intertropical convergence zone along with negative rainfall anomalies in the Sahel and positive rainfall anomalies in the Guinean region. This was the case in 1987. The ENSO warm event during this year had apparently no significant impact on West African monsoon dynamics. A zonal atmospheric coupling associated with differences of SST anomalies between the eastern equatorial Pacific and the Atlantic is evident in the period 1970–88. Positive (negative) phases of this coupling could enhance the impact of ENSO warm (cold) events on West African monsoon dynamics.