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Journal Article: ID no. (ISBN etc.):  0733-3021 BibTeX citation key:  Mathon2002a
Mathon, V., Laurent, H. & Lebel, T. (2002) Mesoscale convective system rainfall in the Sahel. IN Journal of Applied Meteorology and Climatology, 41. 1081–1092.
Added by: Thierry Lebel 2008-12-17 17:26:47    Last Edited by: Fanny Lefebvre 2010-12-22 11:24:20
Categories: General
Keywords: Precipitation, Satellites
Creators: Laurent, Lebel, Mathon
Collection: Journal of Applied Meteorology and Climatology
Bibliographies: Prior150410

Peer reviewed
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Based on a full resolution Meteosat data set, an extensive climatological study of the Mesoscale Convective Systems (MCSs) observed by satellite over the Sahel leads to define a sub-population of MCSs –called OCSs (Organized Convective Systems)- that represent only 12% of the total number of MCSs observed during 9 years over the Central Sahel, while accounting for almost 80% of the total convective cloud cover defined at the 233 K threshold. Using a high resolution rainfall data set, it is shown that these OCSs are also the main source of rain in this region, accounting for about 90% of the seasonal rainfall with a mean areal rainfall of 14.7 mm per system. All the OCSs are associated with a rain event and more than 90% of the major rain events are associated with an OCS These figures are compared to those obtained for MCCs (Mesoscale Convective Complexes). Each MCC produces more rainfall on average (19 mm per system) but there are only a few of them (1.2% of the total number of MCSs) and they consequently produce only 19% of the seasonal rainfall.
The interannual rainfall variability is first determined by the year-to-year fluctuation of the number of events defined from satellite rather than by the fluctuations of their mean rain efficiency. In fact the total rain yield of an OCS appears to be primarily linked to its duration (which itself is largely determined by its spatial extension), rather than to its average rain rate. The diurnal cycle over the region is also studied and it is shown that it is largely conditioned by the propagative nature of the OCSs associated with orography-driven generations located a few hundred kilometers to the east of the validation area.
Added by: Thierry Lebel    Last Edited by: Fanny Lefebvre