1. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Boulder Colorado USA
2. Global Monitoring Division NOAA Earth System Research Laboratory Boulder Colorado USA
3. Institute of Arctic and Alpine Research University of Colorado Boulder Boulder Colorado USA
4. Stratospheric Protection Division, Office of Atmospheric Programs, Office of Air and Radiation U.S. Environmental Protection Agency Washington District of Columbia USA
5. Atmospheric and Environmental Research Lexington Massachusetts USA
6. Environmental Technologies Area Lawrence Berkeley National Laboratory Berkeley California USA
7. Earth and Environmental Sciences Area Lawrence Berkeley National Laboratory Berkeley California USA
8. Centre for Isotope Research University of Groningen Groningen Netherlands