1. Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22904, United States
2. NASA Langley Research Center, Hampton, Virginia 23681, United States
3. National Suborbital Research Center, Grand Forks, North Dakota 58202, United States
4. Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck 6020, Austria
5. Department of Chemistry, University of Oslo, Oslo 0315, Norway
6. Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah 84054, United States