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RESEARCH
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Overview
In the research area multiphase chemistry modeling,detailed aqueous phase mechanisms are developed and applied within numerical models studying the physico-chemical multiphase processing in cloud droplets and deliquescent aerosol particles. The main focus of the model applications is given to the analysis of aqueous phase oxidations und their effect on the tropospheric oxidation capacity. For modelling of the complex tropospheric multiphase system, a spectral 0-dimensional box model as well as the detailed air parcel model SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model; Wolke et al., 2005) which were developed within the modelling department can be used. The currently applied multiphase mechanism consists of a extended RACM-MIM2 gas phase mechanism (Karl et al., 2006; Tilgner et al., 2008) with about 281 Reactions and the aqueous phase mechanism CAPRAM (Chemical Aqueous Phase Radical Mechanism) with up to 777 reactions in the newest version CAPRAM 3.0 (Herrmann et al., 2005). The phase transfer of currently 52 soluble species is treated in the models after the approach by Schwartz (1986; In: Jaeschke, W. (Ed.), Chemistry of Multiphase Atmospheric Systems, NATO ASI Series, Springer, Berlin, pp. 415-471).
Within the aqueous phase chemistry mechanism, particular emphasis was given to chemical processes of organic compounds and radicals such as NO3, OH, SO4-, Cl2-, Br2-, CO3- as well as peroxy radicals. In contrast to other existing aqueous phase mechanisms, CAPRAM 3.0 also includes reactions of organic compounds with up to 4 carbon atoms (alcohols, carbonyls, carboxylic acids) besides the common C1-C2 chemistry. In addition to the original mechanism, a detailed reaction scheme concerning sulphur(IV) oxidation by radicals, transitional metal ions (iron, copper and manganese), peroxides and ozone was included.
Additionally to the basic mechanism of CAPRAM, a further module was developed which contains radical reactions in both phases of species containing halogens. It was shown in the literature that the reactivity of chlorine atoms in the gas phase is comparable to that of OH radicals, so the oxidizing capacity of marine troposphere is influenced significantly by halogen releasing species in aerosols or clouds.
Further information, corresponding references as well as all available mechanisms and reaction modules can be found at the CAPRAM - website for usage. In addition, the latest comments and corrections are available.
Further information on the multiphase modelling with CAPRAM.
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