Reduction of a model describing ozone oscillations in the troposphere: Example of an algorithmic approach to model reduction in atmosphere chemistry

We consider a simplified reaction mechanism from tropospheric chemistry consisting of six chemical species involved in ten dynamic processes. The concentrations of all six species undergo temporal oscillation for some parameter values. An asymptotic approach to reduction of the original six-variable model to a four-variable version is considered together with detailed explanation of the procedure as well as discussion of conditions under which the reduction is possible. The reduced system nearly quantitatively represents the oscillating behavior of the full model and allows elucidation of its basic dynamical features. This approach also can be used to compare various small models of atmospheric chemistry, and to determine their underlying dynamic structure. The method can be systematically applied to larger atmospheric models.