1. Maxwell Technologies, Reston, VA 22091, USA.
2. Center for Monitoring Research, Science Application International Corporation, Arlington, VA 22209, USA.
3. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037, USA.
4. Mission Research Corporation, Newington, VA 22122, USA.
5. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
6. RAND Corporation, 1333 H Street, N.W., Washington, DC 20005, USA.
7. Autometric, Alexandria, VA 22312, USA.
8. Department of Geosciences, University of Arizona, Tucson, AZ 85745, USA.