1. Department of Atmospheric and Oceanic SciencesUniversity of Colorado Boulder Boulder Colorado USA
2. Laboratory for Atmospheric and Space PhysicsUniversity of Colorado Boulder Boulder Colorado USA
3. NorthWest Research Associates Boulder Colorado USA
4. Atmospheric Chemistry Observations and ModelingNational Center for Atmospheric Research Boulder Colorado USA
5. Solar System DepartmentInstituto de Astrofisica de Andalucia Granada Spain
6. Department of Chemistry and BiochemistryOld Dominion University Norfolk Virginia USA