1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China;
2. Institute of Global Environment Change, Xi'an Jiaotong University, Xi'an 710049, China
3. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing 100029, China
4. College of Global Change and Earth System Science (GCESS), Beijing Normal University and Joint Center for Global Change Studies, Beijing 100875, China;
5. Department of Earth Sciences, University of Minnesota, Minneapolis, Minnesota 55455