1. Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, United States
2. Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, Colorado 80301, United States
3. Department of Chemistry and Biochemistry, University of Montana, Missoula, Montana 59812, United States
4. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, United States
5. Department of Chemistry, University of Wisconsin, Madison Wisconsin 53706, United States