1. Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, United States
2. Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, Colorado 80301, United States
3. Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
4. NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
5. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
6. Department of Chemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
7. Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming 82071, United States
8. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, United States
9. Department of Applied Physics, University of Eastern Finland, Kuopio 70211, Finland