Fontaine B., Garcia-Serrano J., Roucou P., Rodriguez-Fonseca B., Losada T., Chauvin F., Gervois S., Sijikumar S., Ruti P., Janicot Serge. (2010). Impacts of warm and cold situations in the Mediterranean basins on the West African monsoon : observed connection patterns (1979-2006) and climate simulations. Climate Dynamics, 35 (1), p. 95-114. ISSN 0930-7575.
Titre du document
Impacts of warm and cold situations in the Mediterranean basins on the West African monsoon : observed connection patterns (1979-2006) and climate simulations
Année de publication
2010
Auteurs
Fontaine B., Garcia-Serrano J., Roucou P., Rodriguez-Fonseca B., Losada T., Chauvin F., Gervois S., Sijikumar S., Ruti P., Janicot Serge
Source
Climate Dynamics, 2010,
35 (1), p. 95-114 ISSN 0930-7575
Using both empirical and numerical ensemble approaches this study focuses on the Mediterranean/West African relationship in northern summer. Statistical analyses utilize skin temperature, sea surface temperature, in situ and satellite rainfall, outgoing longwave radiation (OLR) observations and reanalyzed data winds and specific humidity on isobaric surfaces. Numerical investigations are based on a large set of sensitivity experiments performed on four atmospheric general circulation models (AGCM): ARPEGE-Climat3, ECHAM4, LMDZ4 and UCLA7.3. Model outputs are compared to observations, discussed model by model and with an ensemble (multi-model) approach. As in previous studies the anomalous Mediterranean warm events are associated with specific impacts over the African monsoon region, i.e., a more intense monsoon, enhanced flux convergence and ascendances around the ITCZ, a strengthening of low level moisture advection and a more northward location of ascending motion in West Africa. The results show also new features (1) thermal variability observed in the two Mediterranean basins has unalike impacts, i.e. the western Mediterranean covaries with convection in Gulf of Guinea, while the eastern Mediterranean can be interpreted as Sahelian thermal-forcing; (2) although observations show symmetry between warming and cooling, modelling evidences only support the eastern warming influence; (3) anomalous East warm situations are associated with a more northward migration of the monsoon system accompanied by enhanced southwertely flow and weakened northeasterly climatological wind; (4) the multi-model response shows that anomalous East warm surface temperatures generate an enhancement of the overturning circulation in low and high levels, an increase in TEJ (Tropical Eeasterly Jet) and a decrease in AEJ (African Eeasterly Jet).
Plan de classement
Sciences du milieu [021]
;
Limnologie physique / Océanographie physique [032]
Localisation
Fonds IRD [F B010049603]
Identifiant IRD
fdi:010049603
