1. School of Earth and Atmospheric SciencesGeorgia Institute of Technology Atlanta Georgia USA
2. Now at Atmospheric Sciences and Global Change DivisionPacific Northwest National Laboratory Richland Washington USA
3. Institute for the Study of Earth, Oceans, and SpaceUniversity of New Hampshire Durham New Hampshire USA
4. NASA Langley Research Center Hampton Virginia USA
5. Chemical Sciences Division, Earth System Research LaboratoryNational Oceanic and Atmospheric Administration Boulder Colorado USA
6. Cooperative Institute for Research in Environmental SciencesUniversity of Colorado Boulder Boulder Colorado USA
7. Department of Chemistry and BiogeochemistryUniversity of Colorado Boulder Boulder Colorado USA
8. School of Chemical and Biomolecular EngineeringGeorgia Institute of Technology Atlanta Georgia USA