1. Atmospheric Science Program, Department of Physics, Dalhousie University, Halifax, NS, B3H 3J5 Canada;
2. Meteorological Service of Canada, Downsview, ON, Canada;
3. Pacific Northwest National Laboratory, Richland, WA, USA;
4. Atmospheric Science Division, Lawrence Livermore National Laboratory, CA, USA;
5. Department of Chemistry, University of Cambridge, UK;
6. NASA Goddard Space Flight Center, Greenbelt, MD, USA;
7. National Environmental Research Institute, Roskilde, Denmark;
8. Max Planck Institute for Meteorology, Hamburg, Germany;
9. Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands;
10. Stockholm University, Stockholm, Sweden;
11. NASA/GISS, New York, NY, USA;
12. National Center for Atmospheric Research (NCAR), Boulder, CO, USA;
13. Institute for Marine and Atmospheric Research, Utrecht (IMAU), Utrecht University, Utrecht, The Netherlands