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Journal Article: ID no. (ISBN etc.):  0894-8755 BibTeX citation key:  Chauvin2010
Chauvin, F., Roehrig, R. & Lafore, J.-P. (2010) Intraseaonal variability of the Saharan Heat Low and its link with the midlatitudes. IN Journal of Climate, 23. 2544–2561.
Added by: Romain ROEHRIG 2009-03-20 15:01:19    Last Edited by: Fanny Lefebvre 2010-09-23 10:18:21
Categories: Monsoon system and its variability
Keywords: Intraseasonal variability
Creators: Chauvin, Lafore, Roehrig
Collection: Journal of Climate
Bibliographies: cnrm, Prior150410

Peer reviewed
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The Saharan Heat Low (SHL) is thought to be a key feature of the West African Monsoon (WAM) and its variations during the summer season have not been yet systematically assessed. In order to characterize the intraseasonal variations of the SHL, we applied real and complex Empirical Orthogonal Function analyses on the 850 hPa potential temperature field over Northern Africa and the Mediterranean, using NCEP/DOE AMIP-II Reanalysis. A robust propagative mode is highlighted over North Africa, opposing the Morocco/Mauritania coast to Central Libya in a West/East phase competition. This SHL mode shows a significant periodicity in the 10-20 day range and has been related, thanks to a lag-composite analysis, to large-scale mid-latitude intraseasonal fluctuations of the atmosphere. The southward penetration of wave-like pattern over the North African continent generates modulations of the 3-dimensional atmospheric structure. The Sub-Tropical Westerly Jet, the northerly Morocco coast ventilation and the low level Harmattan-like circulation are particularly impacted during the crossing of the wave, with some effects on the advection of temperature and humidity over North Africa. Moreover, after the occurrence of the West/East phase difference maximum, an enhanced convective signal appears in the Darfur region which propagates westward, as far as middle of the Atlantic, at a speed similar to the well-known African Easterly Waves (AEW).
Added by: Romain ROEHRIG    Last Edited by: Fanny Lefebvre