Anthropogenic Aerosol Effects on Shallow Clouds during the Dynamics-Aerosol-Chemistry-Cloud Interactions DACCIWA Field Campaign in West Africa

The Dynamics-Aerosol-Chemistry-Cloud Interactions field campaign DACCIWA investigates the effects of air pollution on clouds, weather and climate in West Africa. Over this region, aerosol and cloud microphysical properties are poorly constrained by observations, leading to large uncertainties in current weather forecasts and climate predictions. Natural biogenic emissions are mixed with anthropogenic emissions from large cities as well as from biomass burning, vehicle transport and domestic fires in rural areas. Here, we give an overview on cloud properties measured in West Africa and investigate to what extent anthropogenic and natural emissions influence cloud microphysical and radiative properties.

From 27 June to 16 July 2016, three European aircraft performed measurements above Togo, Ghana, Benin and Ivory Coast. A survey of microphysical cloud properties measured with the cloud and aerosol spectrometer CAS-DPOL and the optical array probe 2D-S onboard the DLR Falcon from the boundary layer to the upper troposphere will be given. Differences in marine and continental shallow convection will be presented. A particular focus is the investigation of aerosol effects on low-level stratus clouds. Rarely observed up to now, urbanized areas in the costal hinterland significantly contribute to air pollution in the accumulation mode of the aerosol distribution. This potentially affects the properties of shallow clouds, and thus the local weather and climate.