A Numerical Study Of Nonlinear Internal Waves In The South Of The Yellow Sea

In this paper, on the basis of special topography, the model of internal Kelvin wave for continuous stratified ocean is made, and by using the generalized K-dV model (GKdV model for short) for continuous stratified ocean, the evolution of nonlinear internal tidal wave in the South of the Yellow Sea is modeling.Many observations show that in the Yellow Sea internal tidal waves possess the marked characteristics of internal Kelvin wave, and in the south of the Yellow Sea the nonlinear evolution of internal tidal wave is one of mechanisms producing internal solitary waves. In this paper, the model of internal Kelvin wave for continuous stratified ocean is given, and an elementary numerical study of this model is made in the south of the Yellow Sea. This work provides a base of the posterior study of nonlinear evolution process of internal tidal wave.Following the previous work, in this paper the reflection and nonlinear evolution of semidiurnal internal tidal wave for the first mode from Station A (34°4'N,125°6'E) and Station B (36°34'N,123°51'E) in a westward, southwestward and northwestward direction respectively is modeling, by using the generalized K-dV model (GKdV model for short) for continuous stratified ocean, in which the different impact between background barotropic ebb and flood current is considered. The results of modeling show that, on the propagation of the internal tidal waves and the internal solitary waves, the impaction of the background current is very important. Especially, the different impact between background barotropic ebb and flood current is obligatory, which is the obvious advantage of the GKdV model. The main reason that internal solitary waves are collecting in the south of the South Yellow Sea and seldom existing in the north of the South Yellow Sea is the impact of powerful background baroclinic circulation and very strong background barotropic current in the south of the South Yellow Sea, and on the flood (relative to the west coast of Korea peninsula) the directions of the two currents are the same basically, otherwise the two currents are weak in the north of the South Yellow Sea. During the propagation of the internal tidal waves and the internal solitary waves, the nonlinearity coefficient a is not only related to the amplitude of the internal solitary waves, but also the depth and the stratification of the ocean, the background current and so on. In addition, owing to the impact of very strong background barotropic current of 0.75m/s, the semidiurnal internal tidal wave is not stable from Station A in a northwestward direction.