台湾海峡M2分潮潮汐潮流特征分布及机制研究

Distribution and mechanism of M2 tide and tidal current in Taiwan Strait

台湾海峡同时拥有居我国第二位的大潮区和除无潮点外的小潮区,M2分潮作为主要分量,其潮汐结构的形成机制尚存争议。本研究基于MIKE 21水动力模型,建立了台湾海峡及其周边海域潮汐潮流的数值模型,数值模拟结果与20个验潮站以及4个ADCP(Acoustic Doppler Current Profiler)观测站数据吻合程度良好。根据数值模拟结果分别给出M2分潮在台湾海峡的同潮图、潮流椭圆和潮能通量分布,同时分别针对地形和南边界条件进行敏感性实验。研究结果表明M2分潮受东海传入的潮波控制,潮波受台湾岛以南陡峭地形影响发生反射,由于反射波的迟角与吕宋海峡传入潮波的相近,二者叠加后向北传入台湾海峡,在与南下潮波迟角相同处,出现最大振幅,即在台湾海峡西岸形成强潮区。研究还表明,吕宋海峡传入潮波在台湾岛南缘迟角与南下潮波的相反是出现波节带结构的主要原因,其对台湾海峡西岸振幅增益也起到促进作用。

Taiwan Strait has the second largest tide areas and the second smallest tide areas except for amphidromic points in China.As the main composition of the tide,M2 causes a controversy on the mechanism of tidal structure formation.In this paper,a numerical model of tide and tidal currents in Taiwan Strait is established based on MIKE 21 with a good agreement with long-term observation data of 20 tide observation stations and 4 ADCP observation stations.The distributions of co-tidal,tide ellipse and tidal energy flux for M2 tide are given.To explore the formation mechanism of M2 tide,two sensitivity tests for the topography and southern open boundary conditions were carried out.The results show that the southward incident wave from the East China Sea is reflected to north with a similar phase-lags from the Luzon Strait by the abruptly deepened topography in the south of Taiwan Strait.Two waves transport to the north,and the peak of amplitude occurs where the phase-lags are same,which is the reason of the strong tidal zone in the west of Taiwan Strait.The waves from the Luzon Strait,with contrary phase-lags to the reflected waves also strengthen the amplifications in the west of Taiwan Strait and it is the main reason for tidal band in the southern of Taiwan Strait.