Overview of studies on Qiongdong upwelling

Qiongdong upwelling is seasonal coastal upwelling east of Hainan Island.It usually occurs during April-September with the strongest upwelling in June and July in the area of 18o30’ 20oN and west of 111o30’E,where the summer surface water has low temperature,high salinity,low dissolved oxygen and rich nutrients.In this study,the temporal-spatial characteristics and mechanisms of Qiongdong upwelling are reviewed based on the studies since the 1960s.These studies mainly described basic hydrography,interannual variability,and influences of wind and topography on Qiongdong upwelling.Comparing to the latest studies in coastal upwelling,much work needs to be done on Qiongdong upwelling via comprehensive dynamic and ecologic investigations,on issues such as the interannual variability and its mechanisms,and the interaction between Qiongdong upwelling and large-scale circulation.