1. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado80309, United States
2. NOAA Chemical Sciences Laboratory, Boulder, Colorado80305, United States
3. Department of Chemistry, Williams College, Williamstown, Massachusetts01267, United States
4. Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah84112, United States
5. Department of Atmospheric Science, University of Washington, Seattle, Washington98195, United States
6. Atmospheric Chemistry Observations and Modeling Laboratory, NCAR, Boulder, Colorado80307, United States
7. Department of Chemistry, University of Toronto, Toronto, ONM5S 1A1, Canada
8. Department of Chemistry, University of Colorado, Boulder, Colorado80309, United States