Results: Monitoring of the Montreal Protocol ? Basis for Predicting Ozone Recovery

Reactive inorganic chlorine plays a crucial role in the stratospheric ozone depletion. To stabilize and enable a recovering of the stratospheric ozone layer, the Montreal protocol and its amendments have been implemented in 1987 to stop the emission of chlorinated source gases (e.g., CFCs). These gases are photochemically converted in the stratosphere mainly into HCl, ClONO₂ (Cl_y, see Figure), and the inert F_y species, i.e., HF and COF₂. Therefore, long-term measurements of these species can be used to monitor the effectiveness of the Montreal protocol. This is performed with the Zugspitze FTIR system, currently funded via the EC-Project GEOMON  for this task.

A previous study on a possible response of Cl_y in response to the Montreal protocol has shown a stabilization at high levels after 1998 [Rinsland et al., 2003 ]. We show here our results from an updated study, including ozone and F_y. The goal is to characterize the further trend evolution, i.e., whether a turnover has occurred meanwhile, or not. The results from the Zugspitze FTIR long-term measurement series are presented below.

A detailed trend study including a discussion of the comparison with the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) results is under way [Ruhnke, Sussmann, Borsdorff et al., to be published].

Reference

Rinsland, C. P., Mahieu, E., Zander, R., Jones, N. B., Chipperfield, M. P., Goldman, A., Anderson, J., Russell, J. M., Demoulin, P., Notholt, J., Toon, G. C., Blavier, J.-F., Sen, B., Sussmann, R., Wood, S. W., Meier, A., Griffith, D. W. T., Chiou, L. S., Murcray, F. J., Stephen, T. M., Hase, F., Mikuteit, S., Schulz, A., and Blumenstock, T.: Long-term trends of inorganic chlorine from ground-based infrared solar spectra: Past increases and evidence for stabilization, J. Geophys. Res., 108(D8), 4252, doi:10.1029/2002JD003001, 2003.