A theoretical model of minor constituent distributions in the stratosphere including diurnal variations

A technique of modeling vertical distributions of various neutral minor constituents in the stratosphere is briefly discussed. A steady state solution is first calculated for the solar zenith angle x fixed at the daytime average. Effects of NOx (NO and NO2) and HOx (OH and HO2) on the ozone density have been investigated by using different rate constants for the reactions of O3 with HOx. If larger rate constants, as were observed in recent laboratory measurements, are assumed, the loss rate of [O3] by these reactions could be comparable with the loss rate by the NOx chemistry in the lower stratosphere below ∼20 km. The NO3 chemistry becomes even more important in the very low stratosphere. Possibilities of explaining the low [NO] observed in the lower stratosphere by the chemiluminescence technique have been examined. It seems to be hard to reconcile this low [NO] and the larger [NO2] observed by infrared solar spectral techniques. The diurnal variations are calculated by starting from the steady state solution. The preliminary result indicates that the steady state solution calculated for the daytime-averaged x does not represent the diurnal average for most constituents; the difference is particularly large for N2O5, whose chemical time constant is of the order of a day.