Scenarios for Modeling Multiphase Tropospheric Chemistry

Besides observational data model calculations are a very importanttool for improving our understanding of multiphase chemistryin the troposphere. Before a chemical model can be used for that purposeit is necessary to show that the model does what it is intendedto do. A protocol has been developed thatcan be used as a basis for the verification of the numericsand the correct implementation of thechemical balance equations.The protocol defines meteorological parameters and initial conditionsfor a zerodimensional (box) model. Several scenarios cover the pollutedas well as the remote marine and continental boundary layer and also thefree troposphere. Calculations by different groupswith different modelsand 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 forsensitivity studies.