Test of two numerical solvers for chemical reaction mechanisms in a 3D-air quality model

• Published in: Environmental modelling & software : with environment data news Vol. 15; no. 6; pp. 639 - 646
• Main Authors: Müller, F., Schlünzen, K.H., Schatzmann, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2000
• Subjects: Air quality; Atmospheric chemistry; Boundary layers; Chemical reactions; Mathematical models; Modeling; Numerical methods; Numerical solver; Operator splitting; Ozone layer; Ozone prediction; Problem solving; Three dimensional; Troposphere; Operator splitting; Numerical solver; Air quality; Ozone prediction; Modeling
• ISSN: 1364-8152; 1873-6726
• DOI: 10.1016/S1364-8152(00)00037-2

The three-dimensional air quality model MECTM is used to study the effect of different numerical solvers (Hybrid scheme and QSSA scheme) for the chemical reaction mechanism on the overall development of the concentration of gas-phase species. Special attention is drawn to ozone, over a one day simulation period. Of major interest is the identification of how simultaneously acting processes, such as advection or turbulent mixing, contribute to the change of trace gas concentrations under conditions of operator splitting, and to gain more information about the reliability and robustness of an air quality model. Results indicate that differences in the solution of the chemical reaction system introduced by the use of different solvers are propagating in the model but they do not accumulate with time. For the simulated episode the highest differences between the model results are associated with the region of the boundary layer, while in the free troposphere the concentration differences are homogeneously distributed and in the order of 10%. Ozone production due to chemical processes is mainly related to the upper boundary layer while the layers close to the ground are characterized by inhibition of ozone production due to NO emissions. Turbulent mixing processes counteract spatial concentration gradients caused by chemical reactions which is the main reason for the limitation of further deviation of simulation results.