Scenarios for Modeling Multiphase Tropospheric Chemistry - Lisa

Journal of Atmospheric Chemistry 40: 77–86, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands.

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Scenarios for Modeling Multiphase Tropospheric Chemistry D. POPPE 1, B. AUMONT 2, B. ERVENS 3, H. GEIGER 4, H. HERRMANN 3, E.-P. RÖTH 5 , W. SEIDL 6, W. R. STOCKWELL 7, B. VOGEL 8, S. WAGNER 5 and D. WEISE 3 1 Institut für Atmosphärische Chemie, ICG-3, Forschungszentrum Jülich, 52425 Jülich, Germany,

e-mail: [email protected] 2 LISA, Universite de Paris 12, Creteil, France 3 Inst. für Troposphärenforschung, Leipzig, Germany 4 Inst. für Physikalische Chemie, Universität-GH Wuppertal, Germany 5 Inst. für Physikalische Chemie, Universität Essen, Germany 6 Fraunhoferinstitut (IFU), Garmisch-Partenkirchen, Germany 7 Division of Atmospheric Sciences, Desert Research Inst., Reno, NV, U.S.A. 8 Inst. für Meteorologie und Klimaforschung, FZ Karlsruhe, Germany (Received: 14 November 2000; accepted: 24 January 2001) Abstract. Besides observational data model calculations are a very important tool for improving our understanding of multiphase chemistry in the troposphere. Before a chemical model can be used for that purpose it is necessary to show that the model does what it is intended to do. A protocol has been developed that can be used as a basis for the verification of the numerics and the correct implementation of the chemical balance equations. The protocol defines meteorological parameters and initial conditions for a zerodimensional (box) model. Several scenarios cover the polluted as well as the remote marine and continental boundary layer and also the free troposphere. Calculations by different groups with different models and numerical solvers demonstrate that the protocol is clear and complete. The excellent agreement between the results of all groups are a major step of verification of the participating models. The scenarios may also serve as well documented base cases for sensitivity studies. Key words: troposphere, multiphase chemistry, modeling.

A quantitative understanding of the chemistry of reactive trace compounds in the troposphere is an indispensible tool and the scientific basis of the development of abatement and reduction strategies for environmentally relevant compounds such as photo-oxidants, nitrogen oxides, and acids. Numerical chemistry-transport models (CTM) are the scientific instruments together with observational data to determine the extent to which we have understood tropospheric chemistry. Similar to experimental methods numerical CTMs need intercomparison in order to verify that the models do what they are intended to do (see for example Kuhn et al.,

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1998). We have developed a protocol which, among other things, can be used for that purpose. The protocol describes initial conditions and meteorological parameters to be used to carry out model calculations for multiphase tropospheric chemistry by box models. Cases for 3d-CTMs are also provided, however, emphasis is given to the modeling of multiphase chemistry in box model simulations. The input parameters are designed to initialize numerical simulations in an unambigous manner (we did our best in this matter, however, comments are always welcome), to allow different individuals that use the same chemical scheme to come up with results that differ only by the numerical inaccuracies of the applied algorithms. The scenarios can be used: • for testing numerical solvers, • as base cases for sensitivity studies like – changes in chemistry, in particular impact of updated rate constants, – impact of meteorological parameters, etc. on the concentrations of compounds • for evaluation of chemical reaction schemes that are currently in use for prediction purposes and development of reduction strategies, • and many other things. Six scenarios are defined encompassing the remote planetary boundary layer over the continent (LAND) and the ocean (MARINE), the free troposphere (FREE), and three cases with varying burdens of anthropogenic and biogenic emissions (PLUME, URBAN, and URBAN/BIO). The scenarios LAND, MARINE, and FREE are similar but not identical to the corresponding cases of the 1994 IPCC intercomparison (Prather et al., 1995). Main differences are: • the photolysis frequencies are prescribed rather than calculated by the model to remove the often dominating source for differences between results of different models. • the emissions have been introduced for the PLUME case according to the European emission inventory (Derwent and Jenkin, 1991). • initial conditions are provided not only for gas-phase chemistry but also for multiphase processes, i.e., they also specify typical compositions of cloud droplets and aerosol particles. Two additional scenarios URBAN and URBAN/BIO have been invoked for polluted situations in the continental boundary layer. The URBAN/BIO case is designed to simulate the chemical fate of an air parcel that picks up anthropogenic emissions when passing an industrialized area and that is then transported into a rural environment with biogenic emissions only. The scenarios have been developed by members of the multiphase modeling group within the EUROTRAC-2 project CMD (Chemical Mechanism Development). The latest version of the protocol with a complete description of the

SCENARIOS FOR MODELING MULTIPHASE TROPOSPHERIC CHEMISTRY

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Table I. Models Model

Solver

M1 M2 M3 M4 M5

Facsimilea LSODEb QSSA + Eulerc QSSA + Eulere Vodef

Program package

Author

KAMM-DRAISd

Poppe Aumont Vogel Röth Geiger

SBOXg

a Product of AEA technology, U.K. b Hindmarsh (1983). c Hass (1991) and McRae et al. (1982). d Vogel et al. (1995). e Röth (1982). f Brown et al. (1989). g Seefeld and Stockwell (1999) and references therein.

scenarios, Fortran-source codes for the calculation of the dependence of the photolysis frequencies on the solar zenith angle and also for the temporal development of the cloud droplet size are available on the web under: http://www.fzjuelich.de/icg/icg3/ALLGEMEIN/cmdform.html Results of simulations for O3 , OH, and NOx with all scenarios are shown in Figures 1–6. The calculations use the reaction scheme RADM2 and address gas-phase chemistry only. There is excellent agreement between the results from different models (denoted Mi, see also Table I). The models employ highly sophisticated solvers like the FACSIMILE package (M1) or the free software VODE (M2 and M5). However, also solvers (M3 and M4) that are based on numerically simpler concepts like the QSSA (quasi stationary state approximation) for the short-lived compounds combined with a Euler algorithm for the temporal evolution of the longer-lived species work equally well. Actually the solver of M3 (Hass, 1991) is taken without modifications from the KAMM-DRAIS model package (Vogel et al., 1995), a 3d-mesoscale CTM. The nearly perfect agreement indicates • that the scenarios are completely and unambigously described, • all numerical solvers employed are suitable for the numerical solutions of the chemical balance equations, • the results are verified in the sense, that they are, apart from very small numerical errors, solutions of the balance equations. They can serve as a bench mark for others solvers. It is planned to make results for all scenarios with the gas-phase mechamism RADM2 (Stockwell et al., 1990), a modified aqueous phase reaction scheme (Walcek et al., 1997) and a simplified treatment of heterogeneous processes on aerosols available.

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Figure 1. Mixing ratios for several compounds as function of time for the LAND scenario from different models which incorporate different solvers as specified in Table I. M1 = solid, M2 = dashed, M3 = dotted, M4 = dashed-dotted, M5 = grew dots, gas-phase reaction scheme RADM2 (Stockwell et al., 1990).


Figure 2. Same as Figure 1 except for the MARINE scenario.

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Figure 3. Same as Figure 1 except for the FREE scenario.


Figure 4. Same as Figure 1 except for the PLUME scenario.

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Figure 5. Same as Figure 1 except for the URBAN scenario.


Figure 6. Same as Figure 1 except for the URBAN/BIO scenario.

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Acknowledgements The work is a contribution to the subproject CMD (Chemical Mechanism Development) of EUROTRAC-2. Financial support by the German Bundesminister für Bildung und Forschung within the Troposphärenforschungsschwerpunkt (TFS) is gratefully acknowledged. References Brown, P., Byrne, G. D., and Hindmarsh, A., 1989: VODE: A variable-coefficient ODE solver, J. Sci. Stat. Comput. 10, 1038. Derwent, R. and Jenkin, M. E., 1991: Hydrocarbons and the long-range transport of ozone and PAN across Europe, Atmos. Environ. 25, 1661–1678. Hass, H., 1991: Description of the EURAD chemistry and transport model version2 (ctm2), in A. Ebel and F. M. Neubauer (eds), Mitteilungen aus dem Institut für Geophysik und Meteorologie der Universität zu Köln, Nr. 83, Universität zu Köln. Hindmarsh, A., 1983: ODEPACK, a systemized collection of ODE solvers, in R. Stephen (ed.), IMACS Transactions on Scientific Computation, Scientific Computing Vol. 1, North-Holland, Amsterdam. Kuhn, M. et al., 1998: Intercomparison of the gas-phase chemistry in several chemistry and transport models, Atmos. Environ. 32, 693–709. McRae, G. J., Goodin, W. R., and Seinfeld, J. H., 1982: Numerical solution of atmospheric diffusion equation for chemically reacting flows, J. Comput. Phys. 45, 1–42. Prather, M., Derwent, R., Ehhalt, D., Fraser, P., Sanhueza, E., and Zhou, X., 1995: Other trace gases and atmospheric chemistry, in J. Holton, L. M. Filho, J. Bruce, Lee, Hoesung, B. Callander, E. Haites, N. Harris, and K. Maskell (eds), Climate Change 1994 – Radiative Forcing of Climate Change and an Evaluation of the IPCC IS92 Emission Scenarios, Cambridge University Press. Röth, E. P., 1982: Description of a one-dimensional model for atmospheric chemistry, in Berichte der Kernforschungsanlage Jülich, JÜL-2098, Kernforschungsanlage Jülich. Seefeld, S. and Stockwell, W., 1999: First-order sensitivity analysis of models with time-dependent parameters: an application to PAN and ozone, Atmos. Environ. 33, 2941–2953. Stockwell, R. W., Middleton, P., Chang, J. S., and Tang, X., 1990: The second generation regional acid deposition model chemical mechanism for regional air quality modeling, J. Geophys. Res. 95, 16343–16367. Vogel, B., Fiedler, F., and Vogel, H., 1995: Influence of topography and biogenic volatile organic compounds emissions in the state of Baden-Wuerttemberg on the ozone concentrations during episodes with high temperatures, J. Geophys. Res. 100, 22907–22928. Walcek, C. J., Yuan, H.-H., and Stockwell, W., 1997: The influence of aqueous-phase chemical reactions on ozone formation in polluted and nonpolluted clouds, Atmos. Environ. 31, 1221–1237.