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List of Abstracts 145P-Transformation.42 ID:4329 10:30Molecular compositions and transformations of dicarboxylic acids, ketoacids, α-dicarbonyls in marineaerosols over the western North Pacific during long- range transportKimitaka Kawamura, Eri Tachibana, Tomomi Watanabe, Nobuhiko UmemotoHokkaido University, Institute of Low Temperature ScienceContact: kawamura@lowtem.hokudai.ac.jpA rapid industrial development in China and East Asian countries for last two decades may have seriouslychanged the air quality of the North Pacific. To better understand a long-term atmospheric changes oforganic aerosols in the western North Pacific, we collected marine aerosols on weekly basis at a remoteisland, Chichijima (27°04'E; 142°13'N) in 2001-2009. The island is located in the boundary of westerly andeasterly wind regimes. The aerosol samples were analyzed for dicarboxylic acids, ketoacids and α-dicarbonyls employing butyl ester derivatization followed by GC determination, together with total carbon(TC) and water-soluble organic carbon (WSOC). Homologous series of saturated diacids (C2-C11) weredetected with a predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids.Unsaturated diacids, including maleic (M), fumaric (F), phthalic acids, were also detected together withketoacids and α-dicarbonyls. Concentrations of total diacids fluctuated significantly in a range of 10-600ngm-3 with winter/spring maximum and summer minimum. The maximum was explained by a combinationof enhanced emissions of polluted aerosols and their precursors in Asia and enhanced atmospheric transportto the North Pacific due to the intensified westerly winds. Concentration ratios (range 0.2-28, av. 2.8) of C3to C4 acid showed a maximum during summer, indicating more oxidation of longer-chain diacids to shorterones. Azelaic acid (C9) that is a specific photo-oxidation product of unsaturated fatty acid such as oleic acidshowed a sharp increase relative to other diacids in summer, suggesting enhanced sea-to-air emission ofunsaturated fatty acids followed by photochemical oxidation during summer. On the other hand, M/F ratios(range 0-8.7, av. 1.1) significantly decreased from winter to summer due to photochemical cis-to-transisomerization. We also discuss long-term trends in the concentrations of diacids and related compounds aswell as TC and WSOC.P-Transformation.43 ID:4483 10:30A secondary organic aerosol scheme in 10 reactions: the no frills approach to global aerosol modelling.Kathryn Emmerson, Mat Evans, Martyn Chipperfield, Ken CarslawUniversity of Leeds, UKContact: k.emmerson@see.leeds.ac.ukBox modellers produce large chemical mechanisms to describe the atmosphere explicitly. Whilst largeschemes are useful for representing the detail of the chemistry their computational expense means theycannot be used to simulate the global scale.We have designed a secondary organic aerosol (SOA) scheme which describes the production of 1 genericlumped anthropogenic, and 1 generic lumped biogenic condensable product in just 10 reactions. It is derivedfrom simulations of the highly explicit Master Chemical Mechanism (~13500 reactions) and its smallerrelative, the CRIv2-R5 (~550 reactions) which fill chemical composition space. A parameterisation of thekey processes producing our chemical species is optimized within this chemical composition space. Underthe range of conditions simulated (from clean to very polluted), we find our parameterized SOA scheme sitswithin 20% of the two larger scheme’s results.We have incorporated our SOA scheme into TOMCAT/GLOMAP, our global aerosol microphysics andchemical transport model. We present global fields of anthropogenic and biogenic SOA from this study,iCACGP-IGAC 2010 14 July, 2010