1. Chemical Sciences Division, Earth System Research Laboratory; National Oceanic and Atmospheric Administration; Boulder Colorado USA
2. Cooperative Institute for Research in Environmental Sciences; University of Colorado Boulder; Boulder Colorado USA
3. Department of Chemistry and Biochemistry; University of Colorado Boulder; Boulder Colorado USA
4. Atmospheric Research and Analysis, Inc.; Cary North Carolina USA
5. School of Engineering and Applied Sciences; Harvard University; Cambridge Massachusetts USA
6. Department of Atmospheric and Oceanic Sciences; University of Colorado Boulder; Boulder Colorado USA