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Dieng A. L., Eymard Laurence, Sall S. M., Lazar A., Leduc-Leballeur M. (2014). Analysis of strengthening and dissipating mesoscale convective systems propagating off the West African Coast. Monthly Weather Review, 142 (12), 4600-4623. ISSN 0027-0644

Lien direct chez l'éditeur doi:10.1175/mwr-d-13-00388.1

Titre
Analysis of strengthening and dissipating mesoscale convective systems propagating off the West African Coast
Année de publication2014
Type de documentArticle référencé dans le Web of Science WOS:000345860400014
AuteursDieng A. L., Eymard Laurence, Sall S. M., Lazar A., Leduc-Leballeur M.
SourceMonthly Weather Review, 2014, 142 (12), p. 4600-4623. ISSN 0027-0644
RésuméA large number of Atlantic tropical depressions are generated in the eastern basin in relation to the African easterly wave (AEW) and embedded mesoscale convective systems (MCSs) coming from the African continent. In this paper, the structures of strengthening and dissipating MCSs evolving near the West African coast are analyzed, including the role of the ocean surface conditions in their evolution. Satellite infrared brightness temperature and meteorological radar data over seven summer seasons between 1993 and 2006 are used to subjectively select 20 cases of strengthening and dissipating MCSs in the vicinity of the Senegal coast. With these observed MCSs, a lagged composite analysis is then performed using Interim ECMWF Re-Analysis (ERA-Interim) and Climate Forecast System Reanalysis (CFSR). It is shown that the strengthening MCS is generally preceded by prior passage of an AEW near the West African coast. This previous wave trough is associated with a convective cyclonic circulation in the low and middle troposphere, which enhances the southwesterly flow and then provides humidity to the strengthening MCS, located in the vicinity of the subsequent AEW trough. This is favored by the contraction of the wavelength associated with the two troughs. The sea surface contributes to the MCS enhancement through surface evaporation flux. But this contribution is found to be less important than advection of humidity from the previous wave trough. These conditions are almost not found in the dissipating MCS cases, which dissipate in a dry environment dominated by a subsident and anticyclonic circulation, with generally no interaction with a previous wave trough.
Plan de classementLimnologie physique / Océanographie physique [032]
Descr. géo.AFRIQUE DE L'OUEST ; SENEGAL ; ATLANTIQUE
LocalisationFonds IRD
Identifiant IRDPAR00012578
Lien permanenthttp://www.documentation.ird.fr/hor/PAR00012578

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