1. a International Institute for Earth System Science, Nanjing University , Nanjing , 210093 , PR China
2. b Department of Geography and Planning , Grand Valley State University , Allendale , MI , 49401 , USA
3. c State Key Laboratory of Remote Sensing Science , Institute of Remote Sensing Applications, Chinese Academy of Sciences , Beijing , 100101 , PR China
4. d State Key Laboratory of Earth Surface Processes and Resource Ecology , Beijing Normal University , Beijing , 100875 , PR China
5. e Centre for Earth System Science , Institute for Global Change Studies, Tsinghua University , Beijing , 100084 , PR China