1. D. Kley and H. G. J. Smit, Institut für Chemie und Dynamik der Geosphäre, Forschungszentrum Jülich, 52425 Jülich, Germany.
2. P. J. Crutzen, Max-Planck-Institut für Chemie, Postfach 3036, 55020 Mainz, Germany, and the Center for Clouds, Chemistry, and Climate, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA.
3. H. Vömel and S. J. Oltmans, Climate Monitoring and Diagnostics Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80303, USA.
4. H. Grassl, World Climate Research Programme, World Meteorological Organization, Geneva, Switzerland.
5. V. Ramanathan, Center for Clouds, Chemistry, and Climate, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA.