Effect of changes in stratospheric water vapor on ozone reduction estimates

Abstract

Previous studies of the effect of water vapor on the destruction of ozone in the stratosphere perturbed by NOx or ClX pollutants did not include temperature feedback effects (i.e., they assumed a fixed temperature profile). These studies indicated that if an increase in stratospheric water vapor concentration were induced (perhaps as a result of an increase in the temperature of the tropical tropopause caused by a change in stratospheric ozone), there would be a significant further reduction in total ozone. Our results from using a one‐dimensional transport kinetics model with a fixed temperature profile confirm these earlier findings. However, when the temperature profile is allowed to change as the species concentrations change, the sensitivity of total ozone to changes in water vapor abundance is greatly reduced. In the case of an NOx injection at 20 km there is even a reversal of sign such that an increase in stratospheric water vapor leads to an ozone increase relative to the case with no change in water vapor.