%0 Journal Article
%T Contribution of Isoprene Oxidation Products to Marine Aerosol over the North-East Atlantic
%A Tatu Anttila
%A Baerbel Langmann
%A Saji Varghese
%A Colin O'Dowd
%J Advances in Meteorology
%D 2010
%I Hindawi Publishing Corporation
%R 10.1155/2010/482603
%X 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 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. 1. Introduction Marine aerosols influence the global climate system directly by scattering incoming solar radiation and indirectly by acting as nuclei on which cloud droplets are formed [1, 2]. The magnitude of these effects depend on both the physical and chemical properties of marine aerosols. These properties are tied to the aerosol formation mechanisms which can be classified as primary, such as mechanical production driven by wind interactions at the ocean surface, and secondary which refers to gas-to-particle conversion (including heterogeneous reactions) resulting from the gas phase oxidation of volatile compounds [3]. Recently, considerable research effort has been put into characterizing the contribution of organic compounds to the marine aerosol [4¨C6]. The research has been motivated by the work of O'Dowd et al. [7] who found significant amounts of both water soluble and water insoluble organic aerosol mass in clean marine air. However, the sources of organic carbon are not fully characterized at the present and hence also the relative contributions of primary and secondary processes remain to be evaluated. In this regard, it has been suggested that a potentially important aerosol source is the formation of secondary organic aerosol (SOA) via isoprene oxidation [8]. Several studies have investigated the importance of the SOA formation to the marine aerosol by employing modeling and remote sensing techniques along with laboratory measurements [9¨C11]. Meskhidze and Nenes [9] suggested that SOA formation resulting from
%U http://www.hindawi.com/journals/amete/2010/482603/