1. U.S. Geological Survey, Box 25046, MS 966, Denver, Colorado 80225 U.S.A., wstephens@usgs.gov, odum@usgs.gov
2. School of Earth Atmosphere and Environment, Monash University, Melbourne, Victoria 3800 Australia, michael.asten@monash.edu
3. U.S. Geological Survey, University of Washington, Box 351310, Seattle, Washington 98195 U.S.A., afrankel@usgs.gov