3.4 Chemical Box calculation

 

  

Figure 7: The concentrations of the reference case were calculated using the Gong & Cho solver and the Livermore-ODE-Solver (lsode), using an integration step of 60 sec. The upper panel shows the absolute ozone concentrations. The curves resulting from the Gong & Cho solver and from the lsode solver can not be distinguished, because they are almost identical. The plot also shows the results of case 19 ^a published by Stockwell et al. The lower panel shows the relative deviation in percents ( 100 $\cdot$ ${\frac{c_{\rm gongcho} - c_{\rm lsode}}{c_{\rm lsode}}}$ ) for Ozone and NO ₂ between Gong & Cho and lsode. The maximum deviation found for NO ₂ was 0.12 %.

To check the accuracy of the chemical solver several test calculations were carried out. The case presented here refers to case 19 ^a in Stockwell et al. (1997), which closely resembles the ``PLUME/2'' case in Kuhn et al. (1998). The box model results of our implementation of the Gong & Cho-solver were compared to results obtained using the Livermore ODE-Solver (Hindmarsh; 1983) which is technically based on the Gear-solver (Gear; 1971) and widely accepted as a reference. Furthermore, we compared the results with those obtained by Stockwell et al. (1997). Figure 7 shows an excellent agreement between the results of the Gong & Cho-Solver, and the Livermore solver. Only slight differences to the data of Stockwell et al. (1997) were found. They are mainly due to the different procedures of calculating photodissociation constants.