Effect of odd hydrogen on ozone depletion by chlorine reactions

The odd hydrogen species, especially OH and HO2 are important in the chemistry of the natural stratosphere because of their direct reactions with O and O3 and their role in nitrogen oxide (NOx) cycles. When chlorine is added to the stratosphere the interaction of NOx, HOx and ClX species yields several potential feedback effects for O3 perturbations, some stabilizing and some destabilizing. Here we focus on the effects of HOx on O3 changes due to ClX injections. As ClX selectively attacks the ozone layer above 28 km the layer below tends to be thickened by the increased incidence of solarUV. If HOx densities are high they dampen this radiative feedback and prevent the healing at low altitudes. We demonstrate how the ozone‐layer shape changes under the influence of injected ClX for several choices of key HOx reaction rates. These same reaction rates exert partial control over the apportioning of Cl atoms among HCl, ClO and Cl, over the total amount of HOx, the ratios of OH to HO2 and H2O2 and the ratio of [NO + NO2] to [HNO3]. The uncertainty in these rates leads to at least a factor of three uncertainty in predicted ozone reductions due to ClX injections. © 1976 by the Chinese Geophysical Society