Das Projekt "Entwicklung von Modellen fuer die Aerosol- und Wolkenchemie der Troposphaere" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Troposphärenforschung e.V. durchgeführt. The proposed project is devoted to the development of adequate physico-chemical models for the description of heterogeneous and aqueous phase chemical processes taking place in the troposphere. The systems to be described by the model will be limited to aqueous phase systems, ie the droplets of clouds, fog and rain and the aqueous (wet) aerosol. The model development to be performed in the project will be limited to the so-called 'tropospheric aqueous phase' which includes the aqueous particles dispersed in air. Reactions occuring on solids (ie direct gas-solid interactions) will not be treated in the project. The objectives of this proposal are: 1) To develop an extensive aqueous phase chemical mechanism, including all relevant processes, that will be based on an evaluation of current scientific knowledge ('the overall mechanism'). In particular, the model will include an extended description of organic chemistry and radical processes, 2) To apply tools of sensitivity analysis to the above mechanism in order to check which processes are of the highest importance and also which classes of reaction do not contribute significantly to chemical conversions in the tropospheric aqueous phase, 3) To couple the overall aqueous phase mechanism with an existing and well accepted gas phase chemical RADM2 mechanism, 4) To develop a kinetic description of transport in the aqueous phase, the gas phase and a cross the gas/liquid interface and to use this description in the model, 5) To include heterogeneous gas/aqueous processes in the model and to describe them adequately, 6) To develop a reduced chemical mechanism which may in the future be applied in larger (global) models, 7) To couple the model to a simple description of cloud dynamics for a stratocumulus cloud and to couple the model to a simple wet aerosol model, 8) To introduce into the model emission scenarios which are typical for Europe, ie a marine, a continental polluted and a continental rural scenario, 9) To perform a limited set of laboratory studies on reaction kinetics and uptake coefficients on systems which are of central importance for the overall model but for which data either do not exist or are inconclusive