1. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
2. Key Laboratory of Cryospheric Science and Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
4. School of Geography, Nanjing Normal University, Nanjing 210023, China