Dust and biomass burning aerosol transport in South Atlantic during AEROCLO-sA

We investigate the transport of dust and biomass burning aerosols in South Atlantic during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign in September 2017. A regional Meso-NH simulation has been run using a 12-km horizontal grid-spacing without deep convection parameterization, an on-line dust emission scheme, a passive tracer of biomass burning aerosol (BBA) emitted using the daily Global Fire Emissions Database and online-computed backward trajectories. The simulation captures both the aerosol optical depth and the vertical distribution of aerosols as observed from airborne and spaceborne lidars. It also reproduces the occurrence of deep convection over Congo and stratocumulus over South Atlantic well. A Lagrangian analysis reveals the origin of aerosols in the South Atlantic. Dust aerosols found just above the stratocumulus were emitted from the coasts and the Ethosha Pan a few days earlier. The BBAs located between 1 and 5 km come mainly from Angola in about 3.5 days. The 8-12 km layer is fed by up to 12 % of the air masses that experienced convection over the Congo Basin in the last 5 days. This amount is much reduced in the sensitivity simulation with a deep convection parameterization.