1. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Xinjiang 830011, China
2. Department of Geography, Ghent University, Ghent 9000, Belgium; Sino-Belgian Joint Laboratory for Geo-Information, Urumqi 830011, China; and Sino-Belgian Joint Laboratory for Geo-Information, Ghent 9000, Belgium
3. National Institute of Water and Atmospheric Research, Christchurch 8011, New Zealand