Impacts of dust on West African climate during 2005 and 2006

Abstract. The aim of this study is to understand the impacts of Saharan dust outbreaks on West African climate using a 3-dimensional, hydrostatic, sigma vertical coordinate regional climate model (RegCM). We performed a simulation with the non aerosol version of the model (control case) followed by another simulation using the desert dust module (dust case) implemented in RegCM which includes emission, transport, gravitational settling, wet and dry removal and calculation of dust optical properties for 2005 and 2006. Dynamic and thermodynamic parameters obtained from both versions of the model are intercompared and validated with NCEP/NCAR reanalysis, African Monsoon Multidisciplinary Analysis (AMMA) program data and the Global Precipitation Climatology Project (GPCP) rainfall products. The spatial and temporal distribution of the Aerosol optical depth derived from the desert dust run is compared to available observed aerosol data such as the Aerosol Robotic Network (AERONET) program and satellites data. Using radiosounding data and RegCM outputs, a case study of a strong dust outbreak showed the presence of a stable environment at Dakar, Sal and Nouadhibou stations.

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