1. Center for Arid Environment and Paleoclimate Research, Key Laboratory of Western China's Environmental Systems, Ministry of Education; Lanzhou University; Lanzhou China
2. Tree-ring Laboratory of Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA
3. Key Laboratory of Cyrosphere and Environment, Cold and Arid Regions Environmental and Engineering Research Institute; Chinese Academy of Sciences; Lanzhou China