Zheng Lian, School of Ocean Sciences,China University of Geosciences (Beijing), China; Jin-Zhong Li, Tianjin Hydrology Research Institute, China; Yu Liu, Aerospace Information research Institute, Chinese Academy of Sciences, China; Zheng-long Jiang, School of Ocean Sciences, China University of Geosciences (Beijing), China; Xue-ju Li, Tianjin Hydrology Research Institute, China; Jian-hua Wang, Aerospace Information research Institute, Chinese Academy of Sciences, China