1. Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, Colorado 80301, United States
2. Center for Aerosols and Cloud Chemistry, Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States
3. Department of Environmental Health and Engineering, The Johns Hopkins University, Baltimore, Maryland 21205, United States
4. Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, Colorado 80305, United States
5. Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
6. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
7. Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
8. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States