1. Royal Netherlands Meteorological Institute KNMI De Bilt The Netherlands
2. Department of Geoscience and Remote Sensing Delft University of Technology Delft The Netherlands
3. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Boulder CO USA
4. Department of Chemistry University of Colorado Boulder Boulder CO USA
5. Institute of Environmental Physics (IUP) University of Bremen FB1 Bremen Germany
6. University Cooperation for Atmospheric Research Boulder CO USA
7. National Center for Atmospheric Research Boulder CO USA