Chemical composition and characterization of aerosols off Namibia: results from the AEROCLO-sA project

The western coast of southern Africa off Namibia is characterized by a semi-permanent and widespread stratocumulus (Sc) cloud deck, very frequent coastal fog, and the oceanic northern Benguela upwelling system (nBUS). It is also the crossroad of large quantities of natural and anthropogenic aerosols of distant and local origins (biogenic, anthropogenic, biomass burning, sea salt and mineral dust) from continental and marine sources, with significant differences in terms of physico-chemical and optical properties, water affinity, scale and height of transport, which are not well represented in climate models.

In this presentation we will illustrate the results of the first extensive chemical and microphysical characterisation of aerosol particles in the area that has been conducted since 2016 at  the coastal Henties Bay experimental site (22°6’ S, 14°17’ E) in the framework of the AErosol, RadiatiOn and CLOuds in southern Africa (AEROCLO-sA) and the Atmospheric Research in the Southern Africa and Indian Ocean (ARSAIO) projects.

Synergetic filter sampling and online measurements provide examples of the numerous new particle formation in link with marine biogenic emissions and the apportionment of maritime sulfate aerosols, including their biogenic component.