1. Institute of Arctic and Alpine Research University of Colorado Boulder CO USA
2. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder CO USA
3. Global Monitoring Division, Earth System Research Laboratory National Oceanic and Atmospheric Administration Boulder CO USA
4. Department of Atmospheric and Oceanic Sciences University of Colorado Boulder CO USA
5. Scripps Institution of Oceanography University of California La Jolla CA USA
6. Max Planck Institute Jena Germany