Production of sea spray aerosol in the surf zone

A quantitative source function for sea spray aerosol produced by waves brea king in the surf zone was determined from data collected with optical parti cle counters at both sides of the surf zone at two locations on the Califor nian coast. Three optical particle counters were used to measure profiles a t the base of a pier; a fourth instrument was used at the end of the pier. Careful calibration and intercomparisons of the instruments were made to av oid systematic errors. Aerosol concentrations measured downwind from the su rf, in wind speeds of up to 9 m s(-1), were 1-2 orders of magnitude higher than those upwind. Surf aerosol concentration gradients and plume heights v ary with particle size and with wind speed. The derived surf aerosol source functions are compared with current estimates for the open ocean, taking i nto account the different proportions of the ocean surface covered by white caps. Application of a simple transport model indicates that surf-produced sea spray contributes significantly to the aerosol concentrations at fetche s up to at least 25 km. This has implications for, for example, heterogeneo us chemistry and electro-optical propagation.