ATMOCHEM - Modelling the multiphase evolution of organic carbon in the troposphere: Development of an expert system based on a self generating approach

• Applicant: Dr. Olaf Böge
• Subject Area: Atmospheric Science
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 82756952

Volatile organic compounds emitted in the atmosphere are oxidized in complex reaction sequences. This progressive oxidation leads to the formation of intermediate species with increasing polarity and decreasing vapour pressure. Such organic compounds are subject to transfer into the condensed phases of aerosol particles and cloud droplets and do hence play an important role in tropospheric multiphase chemistry. The magnitude of the environmental effects of those secondary organics remains poorly quantified due to a lack of information concerning the detailed composition of the highly functionalised species. The development of fully explicit chemical schemes appears necessary to explore the evolution of organic carbon during its atmospheric oxidation. However, fully explicit models describing multiphase oxidation will involve a huge number of intermediate species. This fact precludes any attempt to describe the numerous physical and chemical transformations manually. Furthermore, the quantity of physical and chemical data needed to develop explicit models far exceeds available experimental data. LISA and NCAR (Boulder, Colorado) have initiated the development of a data processing tool that allows the development of fully explicit gas phase oxidation schemes based on a self generating approach. The goals of the present project are (i) to extend this expert system to the generation of explicit oxidation schemes in the aqueous phase based on available and recent IfT aqueous phase kinetic data including the currently most detailed aqueous phase chemistry mechanism CAPRAM and a variety of estimation methods, (ii) to explore the evolution of organics in cloudy systems using 0-D box models, (iii) to validate the model results by means of chamber studies for key species of the oxidation mechanism and, finally (iv) mechanism reduction. This combination of mechanism development, application, validation with chamber experiments and reduction will enhance the current multiphase chemistry knowledge and provide the scientific community a complex reference mechanism for the development of simplified mechanisms for applications such as higher scale modelling.

• DFG Programme: Research Grants
• International Connection: France
• Participating Person: Professor Dr. Bernard Aumont