1. Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA.
2. Center for International Earth Science Information Network, Columbia University, New York, NY, USA.
3. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
4. Department of Geosciences and School of Public and International Affairs, Princeton Univeristy, Princeton, NJ, USA.