Influence of the source formulation on modeling the atmospheric global distribution of sea salt aerosol

Abstract

Three different sea salt generation functions are investigated for use in global three‐dimensional atmospheric models. Complementary observational data are used to validate an annual simulation of the whole size range (film, jet, and spume droplet derived particles). Aerosol concentrations are corrected for humidity growth and sampler inlet characteristics. Data from the North American deposition network are corrected for mineral dust to derive sea salt wet fluxes. We find that sea salt transport to inner continental areas requires substantial mass in the jet droplet range, which is best reproduced with the source of Monahan et al. [1986]. The results from this source formulation also shows the best agreement with aerosol concentration seasonality and sea salt size distributions below 4 μm dry radius. Measured wind speed dependence of coarse particle occurrence suggests that above 4 μ the source from Smith and Harrison [1998] is most appropriate. Such sea salt simulations are relevant for assessing heterogeneous chemistry and radiative effects. Sea salt aerosol provides on an annual average, in marine regions, an aggregate surface area equal to 1–10% of the area of the underlying Earth's surface. Together with mineral dust, sulfate, and carbonaceous aerosol the total aerosol surface area globally amounts to 13% of that of the Earth's surface. On the basis of atmospheric column burdens, sea salt represents 21% of the total global aerosol surface area. Equal partitioning of the aerosol surface area among the four components suggests that one has to consider all of them if the global aerosol impact is to be fully determined.