Modeling the spatial distribution of mineral dust and its radiative impact over West Africa during the Dust and Biomass-burning Experiment (DABEX)

The distribution of mineral dust has been widely studied using both regional and global models. Nevertheless, mineral dust is still poorly represented in climate models. To improve our understanding of how to model the spatial distribution, physical and chemical properties and radiative impact of mineral dust, a fully coupled meteorological-chemical-aerosol model (WRF-Chem) is applied over West Africa during the dry season from January to March of 2006. Two different dust emission schemes implemented in WRF-Chem are used to examine the uncertainties in modeling dust emission fluxes. The modeling results of dust spatial distribution and its radiative forcing are evaluated using surface observations from the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) deployment in Niamey, Niger and fully equipped ground-based stations as part of the Aerosol Robotic Network (AERONET) and aircraft measurements collected by the Dust and Biomass-burning Experiment (DABEX) during the winter Special Observation Period of the African Monsoon Multidisciplinary Analysis project (AMMA SOP0). The physical parameters employed in the two schemes are examined and refined via the comparison with measurements of mass and size distributions of dust. The WRF-Chem model generally captures the large amounts of dust emitted during the dust events. The model generally reproduces the double-layer feature of the aerosol measurements with dust in the boundary layer and biomass burning aerosols in the layer above, which could significantly affect the atmospheric stability and the monsoon circulation.