Contribution of Isoprene Oxidation Products to Marine Aerosol over the North‐East Atlantic

Abstract

Secondary organic aerosol (SOA) formation through isoprene oxidation was investigated with the regional‐scale climate model REMOTE. The applied modeling scheme includes a treatment for marine primary organic aerosol emissions, aerosol microphysics, and SOA formation through the gas/particle partitioning of semivolatile, water‐soluble oxidation products. The focus was on SOA formation taking place over the North‐East Atlantic during a period of high biological activity. Isoprene SOA concentrations were up to ~5 ng m −3 over North Atlantic in the base case model runs, and isoprene oxidation made a negligible contribution to the marine organic aerosol (OA) mass. In particular, isoprene SOA did not account for the observed water‐soluble organic carbon (WSOC) concentrations over North Atlantic. The performed model calculations, together with results from recent field measurements, imply a missing source of SOA over remote marine areas unless the isoprene oxidation products are considerably less volatile than the current knowledge indicates.