Modeling sea‐salt aerosols in the atmosphere: 1. Model development

A simulation of the processes of sea‐salt aerosol generation, diffusive transport, transformation, and removal as a function of particle size is incorporated into a one‐dimensional version of the Canadian general climate model (GCMII). This model was then run in the North Atlantic between Iceland and Ireland during the period of January‐March. Model predictions are compared to observations of sea‐salt aerosols selected from a review of available studies that were subjected to strict screening criteria to ensure their representativeness. The number and mass size distribution and the wind dependency of total sea‐salt aerosol mass concentrations predicted by the model compare well with observations. The modeled dependence of sea‐salt aerosol concentration in the surface layer (χ, μg m −3 ) on 10‐m wind speed ( U 10 , m s −1 ) is given by . Simulations show that both a and b change with location. The value a and b range from 0.20 and 3.1 for Mace Head, Ireland to 0.26, and 1.4 for Heimaey, Iceland. The dependence of χ on surface wind speed is weaker for smaller particles and for particles at higher altitudes. The residence time of sea‐salt aerosols in the first atmospheric layer (0–166 m) ranges from 30 min for large particles (r=4–8 μm) to ∼60 hours for small particles ( r =0.13–0.25 μm). Although some refinements are required for the model, it forms the basis for comparing the simulations with long‐term atmospheric sea‐salt measurements made at marine baseline observatories around the world and for a more comprehensive three‐dimensional modeling of atmospheric sea‐salt aerosols.