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Communication incl. Poster: BibTeX citation key:  Gaetani
Gaetani, M., Roucou, P., Fontaine, B. & Baldi, M. 2009. Impacts of warm and cold situations in the Mediterranean Sea on the West African monsoon: intraseasonal variability in climate simulations. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-11-23 20:11:37
Categories: Monsoon system and its variability
Keywords: Intraseasonal variability, Modelling
Creators: Baldi, Fontaine, Gaetani, Roucou
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Many studies have shown that the West African Monsoon (WAM) is teleconnected with phenomena in neighboring regions, in particular the Mediterranean basin (Med) and the Tropical Atlantic for instance, and is also sensitive to perturbations occurring in more remote regions, such as the Indian sub-continent and the Tropical Pacific. These teleconnections are found to be active from intraseasonal to multidecadal timescales. Within this framework, recent studies focused on the teleconnection between WAM and Med (Rowell, 2003; Jung et al., 2006), and showed that a stronger (weaker) WAM is linked to warm (cold) SST anomalies in the Med.
The aim of this work is to diagnose the Med-WAM relationship and to explore the dynamical features of this existing link, focusing on intraseasonal variability. We use outputs from 4 GCMs sensitivity experiments produced in the framework of the AMMA-FP6 project by the CNRM (ARPEGE), IPSL (LMDZ4), UCM (UCLA) and ENEA (ECHAM4), simulating the atmospheric response to warm/cold Med sea during the extended monsoonal season from May to October. We analyze each model individually and the ensemble mean, filtering the daily data in order to remove the synoptic variability.
Results show significant wet rainfall anomalies over the Sudan-Sahel region which are related to warm SST anomalies in the Med, mainly in JAS and east of 0°. In the lower levels, a warm Med produces large positive moisture anomalies over the Med and North Africa, and a strong north-easterly moisture transport from the eastern Med towards the Sudan-Sahel region, feeding the convergence where rainfall anomalies occur. At low levels the MSE gradient between the Guinea coast and the Sudan belt is enhanced and the monsoonal circulation between the ocean and the continent is favored.
Added by: roussot