1. Cooperative Institute for Research in Environmental SciencesUniversity of Colorado Boulder Boulder CO USA
2. National Oceanic and Atmospheric Administration, Chemical Sciences Division Boulder CO USA
3. Department of MeteorologyUniversity of Reading Reading UK
4. Institute for Atmospheric and Climate ScienceETH Zurich Zurich Switzerland
5. Climate and Global Dynamics LaboratoryNational Center for Atmospheric Research Boulder CO USA
6. COSMIC/UCAR Boulder CO USA