Numerical Simulations Of Tide And Tidal Current In The Bohai Sea, Yellow Sea And East China Sea

Using the three dimensional barotropic POM(Princeton Ocean Model) model, tidal movement in the Bohai Sea, Yellow Sea and East China Sea(117°30′E~131°E,27°N~41°N) are numerically simulated. The computational grid is generated by space step 10′×10′, and the number is 82×103. There are 10 sigma layers in the vertical direction. The simulation results were correspond well with the observed tidal harmonic constants. The character of M2 and K1 constituent was analyzed further. Base on the barotropic model, the temperature and salinity fields of annual mean, summer and winter were added to build baroclinic ocean model respectively. It was aimed at studying the influence of baroclinic fields on the tidal movement. Some simulated results are as follows:(1)For the M2 constituent, there are four anticlockwise rotary tidal systems in the whole model area, while for the K1 constituent, the number is two. The simulated co-tidal charts for the two constituents are in good agreement with previous researches. The main tidal type is semidiurnal, and the diurnal area matchups well with the position of semidiurnal tidal amphidromic points.(2)In the Bohai Sea, Yellow Sea and East China sea, nine M2 tidal currentamphidromic points have been found with two in Bohai Sea, five in Yellow Sea, and two in East China sea; thirteen K1 tidal current-amphidromic points have been found, while two in Bohai Sea, four in Yellow Sea, seven in East China sea and the one on the west side of Okinawa Island is found for the first time. The distritution of M2 and K1 tidal current at the surface, the middle and the bottom is the same almostly. Tidal current type is semidiurnal primaryly. The strong current mostly occurs near the harbours and straits in the form of reciprocating flow, however, the weak current appear at open and wide seas mainly as rotational flow. In most area of Bohai Sea and East China sea, the M2 tidal current flows clockwise with anticlockwise tidal flow in Yellow Sea. The K1 tidal current flows anticlockwise in Bohai Sea and Yellow Sea, while it flows opposite in East China sea. As the depth increasing, both of M2 and K1 tidal current velocity decreases and the closer to the seabed, the more it reduces while the the current ellipticity goes larger.(3) Simulated co-tidal charts for M2 tide of annual mean, summer and winter baroclinic model are nearly the same. Amplitude around tidal amphidromic points changes little bit, while in most area it goes down when compared with barotropic model result. For the K1 tide amplitude there exists some difference among the three baroclinic models, however for phase the difference is small. The amplitude distribution of K1 tide in annual mean baroclinic model shows some decrescence in most area of Bohai Sea and Yellow Sea. For summer and winter model, K1 tidal amplitude difference with barotropic model enlarges outward from tidal amphidromic points-centered, and summer model increases greater relatively.(4)In baroclinic model, the distribution of mximum velocity for is basically the same with little decent in the vast majority of area, the same as M2 tidal current ellipses. For K1 tidal current, the velocity strength decreases in the order of summer, winter, annual mean and barotropic while its ellipses appear remarkable difference between barotropic and baroclinic: in some area major and minor axis of ellipses is longer in baroclinic model, and the range of clockwise tidal flow.