ATMOCHEM - Modelling the multiphase evolution of organic carbon in the troposphere: Development of an expert system based on a self generating approach
Final Report Abstract
The study aimed to design a mechanism generator for a fully automated self-generation of large explicit chemical schemes to describe the degradation of organic compounds in the tropospheric multiphase system. The work was prepared by the creation of a large database for aqueous phase kinetic data. Furthermore, prediction methods for the computer assisted automated mechanism construction of aqueous phase chemical oxidation schemes have been evaluated. A gas phase mechanism generator initiated at the LISA, Paris was extended for the description of phase transfer processes between the gas and the aqueous phase and aqueous phase degradation processes of organics. The work was performed in close cooperation with the group of Prof. Dr. Bernard Aumont at the LISA in Paris, France. Upon the design of the expert system to predict the aqueous phase oxidation schemes of organics, the generator was used to advance the multiphase chemical mechanism MCMv3.1-CAPRAM 3.0 at TROPOS, Leipzig. Several new CAPRAM versions have been created with different subsets of more advanced organic aqueous phase chemical schemes. Simulations have been performed for a 'real atmosphere' scenario with non-permanent clouds and for comparisons with chamber runs. Besides the investigations of the concentration-time profiles, detailed analysis of the chemical sink and source fluxes have been performed. Furthermore, chamber experiments have been performed at the LEAK chamber at TROPOS for a comparison of the model results and an evaluation of the expert system. The chosen system with aqueous phase concentrations close to the detection limits of the instruments used for the chemical analysis was not able to detect a significant increase in concentration of particulate organics due to the low relative humidity in the chamber. Therefore, further experiments are planned. However, the gas phase chemistry of the chamber runs could be reproduced by the model and the 'real atmosphere' simulations contributed to a better understanding of the tropospheric multiphase chemistry of organics with model results reproducing the concentration-time profiles of important inorganic and organic substances.
Publications
- Tropospheric Aqueous-Phase Free-Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools, ChemPhysChem, 11, 3796-3822, 2010
Herrmann, H., Hoffmann, D., Schaefer, T., Bräuer, P., and Tilgner, A.
(See online at https://doi.org/10.1002/cphc.201000533) - CAPRAM Mechanism Development - Evaluation of Prediction Methods for Aqueous Phase Rate Constants and Model Results, Goldschmidt Conference, 2011, Prague, Czech Republic
Bräuer, P., Mouchel-Vallon, C., Tilgner, A., Aumont, B., and Herrmann, H.
- CAPRAM Mechanism Development - Evaluation of Prediction Methods for Aqueous Phase Rate Constants of Organics and CAPRAM Mechanim Development, European Geosciences Union General Esembly, Vienna, Austria, 2011
Bräuer, P., Mouchel-Vallon, C., Tilgner, A., Aumont, B., and Herrmann, H.
- CAPRAM Mechanism Development - Development of a Mechanism Generator and its Application in the CAPRAM Mechanism Extension, IGAC International Science Conference, Beijing, China, 2012
Bräuer, P., Mouchel-Vallon, C., Tilgner, A., Aumont, B., and Herrmann, H.
- CAPRAM Mechanism Development: Model Results from an Extendend C3 and C4 Organic Aqueous Phase Chemistry, International Conference on Clouds and Precipitation, Leipzig, Germany, 2012
Bräuer, P., Mouchel-Vallon, C., Tilgner, A., Aumont, B., and Herrmann, H.
- Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase, Atmos. Chem. Phys. Discuss., 12, 24095-24130, 2012
Mouchel-Vallon, C., Bräuer, P., Camredon, M., Valorso, R., Madronich, S., Herrmann, H., and Aumont, B.
(See online at https://doi.org/10.5194/acp-13-1023-2013)
