Quasi-harmonic analysis of tidal current data collected over two days from four anchored stations in Liusha Bay,Guangdong Province

Based on the tidal current quasi-harmonic method for short-term data,series tidal current data collected over two days from the surface,middle and bottom layers(with depth from 4.4to 17.0m) at four anchored stations in Liusha Bay were analyzed.The harmonic coefficients of O1,K1,M2,S2,M4 and MS4 were calculated,and the tidal current ellipse factors of all layers at the four anchored stations were given.The results showed that the tidal current in Liusha Bay was classified as a diurnal tidal current,while that in the outer bay was a regular diurnal tidal current and that of the inner bay was irregular.The northern component of the constituents was generally stronger than the eastern component in the outer bay,but this relationship was reversed in the inner bay.The main direction of the residual current during the observation time was northwest,the maximum velocity of the residual current occurred at the abruptly narrowed area of the inner bay,and the velocity of the residual current at the middle layer was larger than in other areas.The maximum possible velocity in the sea area was between 57 and 107 cm/s at the surface,53～106 cm/s in the middle layer and 34～98 cm/s at the bottom.The diurnal tidal current in the outer bay was a clockwise rotary current,while there was a rectilinear current with a rotary current in the inner bay.