1. State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 340 XuDong Road, Wuhan 430077, Hubei, China, wangxt@whigg.ac.cn, wangshuofan@whigg.ac.cn, zwli@whigg.ac.cn
2. Also at University of Chinese Academy of Sciences, No.19(A) Yuquan Road, Shijingshan District, Beijing 100049, China.
3. Hebei University of Economics and Business, No. 47, Xuefu Road, Xinhua District, Shijiazhuang 050061, Hebei, China, yuehun06@163.com
4. Department of Applied Physics and Applied Mathematics, Columbia University, 500 West 120th Street, Mudd 200, MC 4701, New York, New York 10027 U.S.A., daveyuen@gmail.com