WORKING GROUP 11: ATMOSPHERIC CHEMISTRYRADM2 This atmospheric chemical mechanism was originally developed by Stockwell et al. (1990) for the Regional Acid Deposition Model, version 2 (RADM2) (Chang et al., 1989). The RADM2 mechanism is a compromise between chemical detail, accurate chemical predictions and available computer resources. It is widely used in atmospheric models to predict concentrations of oxidants and other air pollutants. The RADM2 mechanism includes for inorganic species, 14 stable species, 4 reactive intermediates and 3 abundant stable species (oxygen, nitrogen and water). Atmospheric organic chemistry is represented by 26 stable species and 16 peroxy radicals. The RADM2 mechanism represents organic chemistry through a reactivity aggregated molecular approach [Middleton et al., 1990]. Similar organic compounds are grouped together into a limited number of model groups through the use of reactivity weighting. The aggregation factors for the most emitted VOCs are given in Middleton et al., [1990]. A QSSA (Quasi Steady State Approximation) method with 22 diagnosed species,includes 3 derived from a lumped group 3 constant and 38 predicted species is used for the numerical solution. The rate equations for 38 predicted species are solved using a Backward Euler scheme.
Stockwell, W. R., P. Middleton, J. S. Chang, and X. Tang, 1990: The second generation regional acid deposition model chemical mechanism for regional air quality modeling. J. Geophys. Res., 95, 16343-16367. Middleton, P., W. R. Stockwell, and W. P. L. Carter, 1990: Aggregation and analysis of volatile organic compound emissions for regional modeling. Atmos. Environ., 24A, 1107-1133. Chang, J. S., F.S. Binkowski, N.L. Seaman, J.N. McHenry, P.J. Samson, W.R. Stockwell, C.J. Walcek, S. Madronich, P.B. Middleton, J.E. Pleim and H.H. Lansford, 1989: The regional acid deposition model and engineering model. State-of-Science/Technology, Report 4, National Acid Precipitation Assessment Program, Washington D.C. |
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