Main features of rain drop size distributions observed in Benin, West Africa, with optical disdrometers

Sounmaila Moumouni (1, 2) , Marielle Gosset (1, 2) , Etienne Houngninou (3)

1 LTHE - Laboratoire d'étude des transferts en hydrologie et environnement
2 CNRM - Centre national de recherches météorologiques
3 Departement de Physique

As part of the African Monsoon Multidisciplinary Analysis (AMMA) field campaign, rain Drop Size Distribution (DSD) measurements were carried out in Benin, in the Sudanese climatic zone, with optical disdrometers, over 3 rainy seasons. The observed DSDs are well modelled by a gamma distribution, with the value of the shape parameter (μ) close to 5. The average normalized intercept parameter (N0*) is close to 103 mm−1m−3. After classification of the convective and stratiform spectra, it is shown that for a given rain rate the proportion of the bigger drops is higher in the stratiform spectra, consistent with the observed occurrences of ‘N0 jumps' within the squall lines. Specific reflectivity-rain rate (Z-R) relationships were derived for the whole data set, for the squall lines and for the convective and stratiform regions.

Domaines: Hydrologie; Géophysique [physics.geo-ph]

Sounmaila Moumouni, Marielle Gosset, Etienne Houngninou. Main features of rain drop size distributions observed in Benin, West Africa, with optical disdrometers. Geophysical Research Letters, 2008, 35, pp.L23807. ⟨10.1029/2008GL035755⟩. ⟨insu-00389057⟩