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Journal Article: BibTeX citation key:  Joly2010
Joly, M. & Voldoire, A. (2010) Role of the Gulf of Guinea in the inter-annual variability of the West African monsoon: What do we learn from CMIP3 coupled simulations? IN International Journal of Climatology, .
Added by: Mathieu Joly 2010-01-15 09:51:39
Categories: Atmospheric processes, Monsoon system and its variability, Ocean-atmosphere interactions, Weather to Climatic modelling and forecasting
Keywords: Climate, Dynamics, Interannual variability, Precipitation, Seasonal cycle
Creators: Joly, Voldoire
Collection: International Journal of Climatology
Bibliographies: Prior150410

Peer reviewed
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Popularity index:  55.71%
Maturity index:  published

The surface ocean explains a significant part of the inter-annual variability of the West African monsoon (WAM). The present paper explores the role of Gulf of Guinea sea surface temperatures (SST): how is the ocean–atmosphere observed relationship reproduced by state-of-the-art coupled models? The ‘Atlantic Nino’ is the main mode of inter-annual variability in the Gulf of Guinea. SST anomalies are maximum in June–July, and are associated with a convective anomaly in the marine Intertropical Convergence Zone (ITCZ), which spreads over the Guinean coast. In most of the studied CMIP3 simulations, the inter-annual variability of SST is very weak in the Gulf of Guinea, especially along the Guinean Coast.
As a consequence, the influence on the monsoon rainfall over the African continent is hardly reproduced. Interestingly, many models exhibit a dipolar response of the marine ITCZ to the Atlantic Nino. In the observations and reanalyses, the absence of any evident shift in the position of the monsoon rainbelt is associated with a collapse of the correlations between Gulf of Guinea SST and Sahel rainfall at the end of the twentieth century. It is suggested that this may be due to the counteracting effects of the Pacific and Atlantic basins over the last decades. In CMIP3 simulations, the Atlantic Nino is often correlated with the El Nino Southern Oscillation (ENSO). However, only one simulation catches the observed evolution of the Pacific–Atlantic relationship at the end of the century.
Added by: Mathieu Joly    Last Edited by: Fanny Lefebvre