Mechanisms of low-frequency sea level fluctuations in the Hangzhou Bay

low-frequency sea level fluctuations in the Hangzhou Bay in winter and summer,1973-1974 are analyzed in this paper.The established multi-spectrum response models effectively identify the different dynamical factors and their contributions to the low-frequency sea level fluctuations inside the bay.The results show that the Ekman transport due to longshore winds is the major mechanism to induce the sea level fluctuations,more important than the frictional effect of local winds.There also exists obviously the influental effect of the free fluctuations of the continental shelf.In addition,a simple estimation suggests that the remarkable sea level fluctuation of 0.4 d^-1 in the bay is related to the resonance of the Huanghai Sea and the Bohai Sea (taken as a single bay).