Yuanlong Li, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China, Weiqing Han, University of Colorado Boulder, Boulder, CO, United States, Lei Zhang, University of Colorado Boulder, Department of Atmospheric and Oceanic Sciences, Boulder, United States and Fan Wang, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Chinese Academy of Sciences Key Laboratory of Ocean Circulation and Waves, Qingdao, China