Mineral dust over west and central Sahel: Seasonal patterns of dry and wet deposition fluxes from a pluriannual sampling (2006-2012)

Abstract : Total and wet mineral dust deposition has been monitored since 2006 at three Sahelian stations in Senegal, Mali, and Niger, respectively at the weekly and the event time scale. Average annual deposited mass fluxes range from 75 to 183 g m À2 yr À1 , from west to east. Deposition fluxes exhibit a clear seasonal cycle in Mali and Niger. High wet deposition fluxes result from an optimum phasing between dust concentration and precipitation: the maximum occurring at the beginning of the wet season, after the maximum of dust concentration and before the precipitation maximum. The contribution of wet to total deposition varies from 67% in Mali to 8% in Senegal. It is the main factor of variability of the deposition fluxes from year to year and at the seasonal scale in Niger and Mali. Wet deposition fluxes in Mali and Niger are mainly due to the wash out of dust emitted by convective systems. In Senegal, the deposition fluxes are lower and dominated by dry deposition (92% of the annual deposition flux). This is due to the low occurrence of convective systems producing local dust emissions and intense wet deposition. The dry deposition fluxes are primarily driven by the variability of the dust concentration. The dry deposition velocities derived from our measurements are consistent with those estimated by theoretical models. Scavenging ratios computed from the measured wet deposition fluxes, dust concentrations, and precipitation are anticorrelated with precipitation amounts. This suggests that most of the atmospheric dust is scavenged at the very beginning of the precipitation events.
Complete list of metadatas

Cited literature [61 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-02324418
Contributor : Gilles Bergametti <>
Submitted on : Monday, October 21, 2019 - 10:04:17 PM
Last modification on : Wednesday, February 19, 2020 - 2:50:36 PM
Long-term archiving on: Wednesday, January 22, 2020 - 7:36:34 PM

File

marticorena et al., J.G.R., 20...
Publisher files allowed on an open archive

Identifiers

Citation

B. Marticoréna, B. Chatenet, Jean-Louis Rajot, G. Bergametti, A. Deroubaix, et al.. Mineral dust over west and central Sahel: Seasonal patterns of dry and wet deposition fluxes from a pluriannual sampling (2006-2012). Journal of Geophysical Research: Atmospheres, American Geophysical Union, 2017, 122 (2), pp.1338-1364. ⟨10.1002/2016JD025995⟩. ⟨hal-02324418⟩

Share

Metrics

Record views

92

Files downloads

122