1. National Aeronautic and Space Administration, Goddard Space Flight Center, Greenbelt, MD 20771, USA.
2. California Institute of Technology, Divisions of Engineering and Applied Science and Geological and Planetary Sciences, Mail Stop 100-23, Pasadena, CA 91125, USA.
3. Department of Geography, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
4. Institute of Marine and Coastal Sciences, Rutgers, State University of New Jersey, New Brunswick, NJ 08901, USA.
5. Carnegie Institution of Washington, Department of Plant Biology, 260 Panama Street, Stanford, CA 94305, USA.
6. Scripps Institution of Oceanography, 8605 La Jolla Shores Drive, La Jolla, CA 92037, USA.
7. Science Systems and Applications Incorporated, National Aeronautic and Space Administration, Goddard Space Flight Center, Greenbelt, MD 20771, USA.