Development of a 2D marine aerosol transport model: Application to the influence of thermal stability in the marine atmospheric boundary layer

The present paper deals with the implementation of the Marine Aerosol Concentration Model (MACMod) in a Mediterranean coastal area. MACMod is a 2D unsteady model dedicated to the atmospheric transport of marine aerosols in the Marine Atmospheric Boundary Layer (MABL). The model predictions were compared to aerosol size distributions measured during experimental campaigns conducted in the French coastal Mediterranean area, for various experimental conditions. The results show a good agreement between the model calculations and the experimental data. In addition, the influence of the main parameters governing the transport of sea-salts in the MABL in case of offshore winds is investigated using model calculations. In particular, our work allows quantification of decrease or increase in concentrations dependent on the thermal stability conditions (compared to neutral case). It is also found that the thermal stability has an increased effect for low wind speeds. The concentration at 10 m height of submicron and supermicron aerosols show an opposite behavior with regard to the stability conditions, i.e., concentration of the former is increased for stable conditions, whereas it is decreased for the latter. When the wind speed exceeds 15 ms− 1, the thermal stability effect is lowered.

Research highlights
► Validation by comparison with data acquired during experimental campaigns.
► Effect of ASTD on turbulent vertical mixing.
► Effect of thermal stability: aerosol concentration ratios at 10 m height.