1. Chemical Sciences DivisionNOAA Earth System Research Laboratory Boulder CO USA
2. Cooperative Institute for Research in Environmental SciencesUniversity of Colorado Boulder CO USA
3. Department of Atmospheric Sciences, RSMASUniversity of Miami Miami FL USA
4. National Center for Atmospheric Research Boulder CO USA
5. Global Monitoring DivisionNOAA Earth System Research Laboratory Boulder CO USA
6. Department of Environmental ScienceAmerican University Washington DC USA