1. Lawrence Berkeley National Laboratory, Berkeley, California and Cooperative Institute for Research in Environmental Sciences, and NOAA/ESRL/PSD, Boulder, Colorado
2. University of Illinois at Urbana–Champaign, Urbana, Illinois
3. National Center for Atmospheric Research, Boulder, Colorado
4. Cooperative Institute for Research in Environmental Sciences, and NOAA/ESRL/PSD, Boulder, Colorado
5. University of Wisconsin—Madison, Madison, Wisconsin
6. University of Alaska Fairbanks, Fairbanks, Alaska