Progress in the determination of the sea spray source function using satellite data

Abstract

Sea spray aerosol influences climate considerably through both direct and indirect aerosol effects. Climate models contain a sea spray source function, i.e. the emission rate of sea spray aerosol droplets per unit area of the sea surface, currently parameterised in terms of wind speed and sea surface temperature (SST). The uncertainty between different formulations of the sea spray source function, and thus associated with the calculated emission fluxes for sea spray aerosol, is more than a factor of 2. In addition, the fraction of organic material in sub-micrometer sea spray droplets is highly uncertain. It is expected that improved estimates can be obtained by inclusion of factors, such as wave conditions, whitecap fraction, improved SST, salinity, and chlorophyll concentration. We aim to incorporate these factors in a new sea spray emission model constrained by the use of satellite observations. Here, we present a methodology for estimating the global primary marine sub-micron organic matter emission. As a first estimate we found an annual global emission of about 20 TgC.