The Internal Wave Propagation Equation And Parametric Inversion Research In The3-layer Stratification Ocean

The internal wave is a kind of nonlinear wave motion in stratified fluids of theglobal ocean. Generally, it is generated by tidal currents that encounter roughtopography on the bottom of the ocean. A lot of internal waves in South ChinaSea(SCS) have been detected from remote images, so the research on them becomespopular in recent years. The large-amplitude internal wave, frequently occurs in deepsea, can bring the transport of mass and momentum in a great level. So internal waveplays important roles in maintaining the ocean circulation and global climate. Inaddition, the internal wave is closely related to human activities such as drillingplatforms, submarine navigation, and underwater communication. The sea water willhave strong inertia and stress force induced by the tremendous energy of internalwave, which could cause adverse effects on the activities above.In this paper, we are going to use numerical simulation combined with remotesensing to study the internal wave. First, we should establish a theoretical model: thenonlinear Schrodinger(NLS) equation in a3-layer stratification configuration fluid.Based on the model, we could carry out numerical simulation and parametricinversion of internal wave. At last, we analyze the results and launch the modelverification work. More details are as follows:First, the establishment of NLS for internal wave propagation. Assuming that theocean water is stratified in a3-layer model, we begin with the Laplace formula andBernoulli formula from hydromechanics. By introducing the multiple scale and withthe method of perturbation expansions, the governing equation could be transformedinto the NLS equation. Meanwhile, we obtain the analytic solution and analyze thephysical significance of some parameters in the equation.Second, the numerical simulation based on NLS equation. We use the stepFourier method to solve the NLS equation numerically. The solution could be put inthe MATLAB program. We collect the ocean environment data of the deep basin area in SCS, so the simulation will run referred to these data. The result demonstratesthat in deep basin the width of waveform has been broadening and the amplitudedecreases. What’s more, the evolution trend in the deep sea of SCS under differentinitial conditions will come to the same results. So we could conclude it is not theinitial conditions but the ocean environment that influence the internal wave evolutionform.Finally, the internal wave parameter inversion. We present the SAR remotesensing detective model based on NLS equation, and obtain the necessary data inDongSha area of SCS as well as Malin shelf edge of UK. These preparatory work willhelp us to inverse the wave amplitude and group velocity in both area. The inversionresults are in accordance with situ data or remote sensing data. This agreement provesthat our NLS equation in3-layer system is suitable for describing internal wavepropagation. So our work is feasible in this paper.