东山湾位于台湾海峡南口的西岸,属于潮控型半封闭海湾.本文章通过对M1站1周年的流速、流向及对应的风速、风向资料进行分析,结果表明:M1站正压流动特征显著,潮流日不等现象较明显,相邻潮次中涨急流速明显小于落急流速.观测期间,M1表、中、底3层实测最大涨潮流速分别为83,78,71 cm/s,实测最大落潮流速分别为152,104,100 cm/s.夏季表层余流流速明显大于中层和底层,冬季各层余流速相差则较小.径流是M1站的余流的主要因子.夏季,径流对表层作用最为明显,其余流流速明显大于中层和底层,中、底层由于受温盐跃层产生的斜压效应作用,出现较长时段的北向余流;冬季东山湾平面和垂向温、盐分布均匀,各层余流流向均为落潮方向,且表层往底层方向,流速变幅不大.由于其半封闭型的海湾形态,风应力对东山湾的余流贡献较小.%The Donshan Bay is a tide-controlled and semi-enclosed bay located along the western coast of the southern end of the Taiwan Strait.The speeds and directions of tidal current and corresponding wind speeds and directions observed at Station M1 in a whole year are analyzed.The results show that at Station M1 the barotropic flow is significant,the diurnal inequality of tidal current is evident and the velocities of maximum flood are obviously smaller than those of maximum ebb between two adjacent tidal periods.During the observation period at Station M1,the maximal flood velocities measured in the surface,the middle and the bottom layers are 83 cm/s,78 cm/s and 71 cm/s respectively and the maximal ebb velocities measured in the three years are 152 cm/s,104 cm/s and 100cm/s respectively.In summer the residual current speed in the surface layer is obviously greater than those in the middle and the bottom layers,whereas in winter the residual current speeds show a small difference among the three layers.The river runoff is the main factor influencing the residual current at Station M1 in summer,particularly to that in the surface layer.As a result,the residual current speed in the surface layer is obviously greater than those in the middle and the bottom layers,in which a northward residual current occurs in a long time period due to a baroclinic effect caused by the influence of high salinity from the open sea.In winter the horizontal and vertical distributions of temperature and salinity in the Dongshan Bay are so homogeneous that the direc tions of the residual current in the three layers are all in the ebb direction and its speed has no big change in amplitude from the surface to the bottom.The wind stress contributes little to the residual current in the Dongshan Bay because of the semi enclosed morphology of the bay.
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