1 Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA 50011 USA.
2 Laboratory for Remote Sensing and Environmental Change (LRSEC), Department of Geography and Earth Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223 USA.
3 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 China.
4 University of Chinese Academy of Sciences, Beijing, 100049 China.