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Rainfall types over southern West Africa: Objective identification, climatology and synoptic environment

Maranan, M.; Fink, A. H.; Knippertz, P.

Abstract:
Southern West Africa (SWA) is characterised by a wide range of rainfall types, the relative importance of which have never been quantified on a regional level. Here, we use 16 years of three‐dimensional reflectivity data from the Tropical Rainfall Measuring Mission–Precipitation Radar (TRMM‐PR) to objectively distinguish between seven different rainfall types in three subregions of SWA.

Highly organized Mesoscale Convective System (MCS) events are the dominating rain‐bearing systems in SWA. They tend to occur in highly sheared environments as a result of mid‐level northeasterlies ahead of a cyclonic vortex. Their contribution to annual rainfall decreases from 71% in the Soudanian to 56% in the coastal zone. MCSs in SWA also propagate slower than their Sahelian counterparts and occur predominantly at the start of the first coastal rainy season. However, in terms of numbers, about 90% of rainfall systems are weakly organized classes, particularly small‐sized, highly reflective and moderately deep (40 dBZ at altitude <10 km) systems. Contrary to MCSs, less organized convection typically occurs during and after the passage of a cyclonic vortex within a regime of deep westerly anomalies, low wind shear and low to moderate CAPE (convective available potential energy), bearing some resemblance to what has been termed “monsoon” or “vortex rainfall”. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000084820
Veröffentlicht am 09.10.2018
Originalveröffentlichung
DOI: 10.1002/qj.3345
Scopus
Zitationen: 9
Web of Science
Zitationen: 10
Coverbild
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Forschungsbereich Troposphäre (IMK-TRO)
Publikationstyp Zeitschriftenaufsatz
Jahr 2018
Sprache Englisch
Identifikator ISSN: 0035-9009
urn:nbn:de:swb:90-848205
KITopen-ID: 1000084820
HGF-Programm 12.01.02 (POF III, LK 01)
Erschienen in Quarterly journal of the Royal Meteorological Society
Band 144
Heft 714
Seiten 1628-1648
Vorab online veröffentlicht am 15.07.2018
Nachgewiesen in Scopus
Web of Science
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