1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder,
Colorado 80305, United States
2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United
States
3. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771,
United States
4. Science Systems and Applications, Inc., Lanham, Maryland
20706, United States