Modeling coastal aerosol transport and effects of surf-produced aerosols on processes in the marine atmospheric boundary layer

The Coastal Aerosol Transport (CAT) model was developed to study the evolut ion of aerosol particle size distributions and composition in the coastal e nvironment. The model simulates such processes as particle production at th e sea surface, mixing of particles through the boundary layer by turbulent diffusion, gravitational settling, and dry deposition. The model is initial ized at the shoreline with continental and/or surf aerosol. An empirical so urce function was developed which better accounts for the production of sub micron particles than current formulations. Continental and sea spray parti cles are treated separately to account for effects of processes depending o n chemical composition. CAT has been tested by comparison with independent data sets as regards the prediction of particle size distributions, the win d speed dependence of sea-salt aerosol mass concentrations, and the evoluti on of sea spray aerosol plumes generated over the surf zone. The model was applied to study effects of sea spray aerosol produced in the surf zone on sea spray concentrations, the composition of continental/sea spray aerosol mixture, the uptake of nitric acid by sea spray aerosol, and the effect of the latter process on nitric acid profiles. The results lead to the conclus ion that surf-produced aerosol cannot be neglected in studies of processes involving sea spray aerosol in the coastal atmospheric boundary layer.