1. Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA.
3. Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO 80309, USA.
4. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA.
5. Laboratoire des Sciences du Climat et de l’Environnement, UMR CEA-CNRS-UVSQ/IPSL 8212, Gif-sur-Yvette, France.
6. Center for Ice and Climate, University of Copenhagen, Copenhagen, Denmark.
7. Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA.
8. National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA.
9. National Center for Atmospheric Research, Boulder, CO 80305, USA.
10. Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.
11. Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA.
12. Environmental Studies Program, University of Colorado, Boulder, CO 80309, USA.
13. Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.