1. Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, and Collaborative Innovation Center for Western Ecological Safety, Lanzhou University, Lanzhou, China;
2. Collaborative Innovation Center for Western Ecological Safety, Lanzhou University, Lanzhou, China;
3. Key Laboratory of Geographic Information Science, Ministry of Education, and School of Geographic Sciences, East China Normal University, Shanghai, China;
4. Key Laboratory for Semi-Arid Climate Change, Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China