National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
National Oceanic and Atmospheric Administration, Atmospheric Chemical Kinetics Group, NOAA Aeronomy Laboratory, Mail code R/AL2, Boulder, CO 80305-3328 United States
University of Bern, Institute of Physics, Space Research and Planetary Sciences, Sidlerstr. 5, Bern, BE 3012 Switzerland