1. Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah;
2. Department of Atmospheric and Oceanic Sciences, University of Wisconsin–Madison, Madison, Wisconsin;
3. Norwegian Meteorological Institute, Oslo, Norway;
4. Luleå University of Technology, Kiruna, Sweden;
5. Space Science and Engineering Center, University of Wisconsin–Madison, Madison, Wisconsin, and Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan;
6. Space Science and Engineering Center, University of Wisconsin–Madison, Madison, Wisconsin;
7. Swedish Meteorological and Hydrological Institute, Norrköping, Sweden;
8. University of Oslo, Oslo, Norway