Biomass-burning smoke drives large uncertainty in climate projections of Earth’s radiative balance. This is due to chemical and physical evolution of smoke and its impact on clouds and radiation. Here we focus on the southeastern Atlantic region and its inflow of African biomass-burning smoke during August 2017. We evaluate smoke properties and processes in two coupled earth-system models, the Energy Exascale Earth System Model (E3SM) and Community Earth System Model (CESM). These are compared against in situ aircraft observations from two field campaigns, ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) and CLoud–Aerosol–Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017). Observations reveal both an increase and subsequent decrease in smoke mean diameter, and a consistent decrease in the mass ratio of organic aerosol (OA) to black carbon aerosol (BC) (OA:BC) over 4-12 days of aging. Both trends are generally not captured by the base configurations of the models. Implementation of a photolytic loss scheme for secondary organic aerosol (SOA) and a ~1-day conversion for primary OA to SOA significantly improves the representation of this loss. In the boundary layer, both models show dimethyl sulfide driving a large increase of sulfate aerosol mass fraction from the free troposphere which is consistent with observations. Finally, models tend to underpredict cloud droplet number concentration partially due to displaying weak turbulent updraft strength, as results improve when increasing this quantity to better match observations. These results are expected to provide insights into future model developed to reduce climate model uncertainties.