1. a International Institute of Earth System Science , Nanjing University , Nanjing, Jiangsu, China , 210093
2. b Meteorological Observatory of Jiangsu Province , Nanjing, Jiangsu, China , 210008
3. c School of Geographic and Oceanographic Sciences , Nanjing University , Nanjing, Jiangsu, China , 210093
4. d Department of Geography , University of Toronto , Toronto, Ontario, Canada , M5S 3G3