A reduced model for complex oscillatory responses in the mesosphere

A kinetic model for chemical reactions in the mesosphere, previously shown to support simple and complex oscillatory responses, is examined. The underlying chemical origins of the change between different oscillatory responses is rationalised in terms of the evolution of the concentrations of the HOx species. Mechanism and variable reduction methods are employed to produce a 12 reaction scheme with two dynamic variable concentrations ([H] and [O], with [OH], [HO2] and [O3] treated through the dynamic steady-state approximation). The reduced model is used to investigate the effect of species transport longitudinally. The latter shows that complex responses can still arise, but that high transport rates eventually lead to a synchronous state in which the concentrations of the species become effectively constant in space and time.