1. Department of Atmospheric & Oceanic Sciences, University of Colorado, Boulder, Colorado 80309, United States
2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
3. Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, United States
4. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
5. LISA, IPSL, CNRS UMR 7583, Université Paris Est and Paris Diderot, Créteil Cedex, France
6. Department of Meteorology, Pennsylvania State University, University Park, Pennsylvania, United States