1. Key Laboratory of Western China’s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, China
2. Department of Geography, Texas A&M University, College Station, Texas
3. Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, Colorado
4. State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China