1. a Hydrology and Remote Sensing Laboratory , Agricultural Research Service, US Department of Agriculture , Beltsville , MD , 20705 , USA
2. b Biospheric Sciences Laboratory , NASA Goddard Space Flight Center , Greenbelt , MD , 20771 , USA
3. c Nanjing Institute of Geography & Limnology , Chinese Academy of Sciences , Nanjing , 210008 , China
4. d Department of Earth & Environmental Systems , Indiana State University , Terre Haute , IN , 47809 , USA
5. e State Key Laboratory of Earth Surface Processes and Resource Ecology , Beijing Normal University , Beijing , 100875 , China
6. f Department of Geography , University of North Carolina at Chapel Hill , Chapel Hill , NC , 27599 , USA