1. a Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin, China
2. b Key Laboratory of Western China’s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, China
3. c Institute of Meteorology and Climate Research (IMK-IFU), Karlsruhe Institute of Technology, Campus Alpin, Garmisch-Partenkirchen, Germany
4. d School of Biological Sciences, The University of Hong Kong, Hong Kong, China
5. e Department of Mathematics, The University of Hong Kong, Hong Kong, China
6. f Institute of Geography, University of Augsburg, Augsburg, Germany