Changes in Stratospheric ClO and HCl Concentrations Under Different Greenhouse Gas Emission Scenarios

In this study, comparison of model results and satellite observations reveals that the Whole-Atmosphere Community Climate Model (WACCM-3) reasonably well reproduced the distributions and seasonal vari-ations of ClO and HCl concentrations. In three greenhouse gas emission scenarios (A1B, A2, and B1), the ClO, Cl, ClONO2, and HCl concentrations would gradually decrease with time as emissions of ozone depleting substances (ODS) steadily decrease. The rates of the changes in the ClO, Cl, ClONO2, and HCl concentrations are different in the same emission scenario and the rates of change in the same composition concentration are different for different emission scenarios. The ClO, Cl, and ClONO2 concentrations de-crease fastest in scenario A2, next fastest in scenario A1B, and slowest in scenario B1. In contrast, the HCl concentration decreases fastest in scenario B1. The ozone concentration recovers quickly, and is highest in scenario A2. The results show that a rapid decrease in the ClO concentration is an important reason for the accelerated recovery of the ozone layer in scenario A2.