1. Department of Geography, University of Maryland, College Park, MD 20742, USA
2. Biospheric Sciences Branch, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
3. US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA 20771, USA
4. USGS Earth Resources Observation and Science (EROS) Center, Sioux Falls, SD 57198, USA