NONLINEAR CHEMICAL COUPLINGS IN THE TROPOSPHERIC NOX-HOX GAS-PHASE CHEMISTRY

A bifurcation phenomenon with relevance to atmospheric chemistry is di scussed. The gas-phase reactions in the troposphere exhibit two types of temporal evolution which are controlled by the strength of the sour ce, Q, of nitric oxide, NO, via the nonlinear chemical coupling betwee n the hydrogen oxides and nitrogen oxides chemistry. If Q remains belo w a threshold value, all short-lived species, including NO, approach s teady-state concentrations, while above the threshold bifurcation to a nother state with increasing (nonstationary) NO concentrations accompa nied by a depletion of the OH and HO2 abundances takes place.