Current, Wave Models And Long-Term Mass Transport Separation Study

There are two parts in this paper. In the first part, a series of current and wave models from near-shore sea to inshore water are set up by improving numerical method and integrating models, and they are used in numerical simulations and forecasts. In the second part, the models from the first part are used in the separated study of long-term mass transport in the Changjiang Estuary, and the separability of long-term mass transport in Estuary and its study method are discussed. The main fruits are as following.1. Some new methods for universal difficulty in physical ocean numerical calculation are put forward. Firstly, the concept of local area is brought forward, and the method of subtracting local averaged density stratification is used in the numerical schemes of baroclinic pressure gradient terms in σ coordinate, which can improve the calculation precision of baroclinic pressure gradient. Secondly, a new Euler-Lagrange method for salinity and temperature calculation is put forward to enhance their calculation precision, in which first-order and second-order Lagrange interpolation are combined and the length of the curvilinear grid is also considered in the interpolation. Thirdly, a new σ-z coordinate are designed to keep the virtues of a and z coordinates and minish their shortcomings. It adopts σ coordinate for current, z coordinate for temperature and salinity in the vertical direction, and Euler-Lagrange method is used to join the calculation of current, temperature and salinity. Finally, putting forward the concept of wave fluctuating layer, the mathematical model and its parameterized model for wave induced excess flow of momentum is set up, with which the impact of wave induced flow of momentum on three-dimensional current can be calculated.2. By integrating numerical methods and ocean models, a series of current and wave models from near-shore sea to inshore water are set up, which are used in numerical simulations and forecasts. Firstly, ECOM-σ-z model is designed by joining some numerical methods into ECOM model, which are from the above-mentioned new methods of this paper or from others' studies. Secondly, ECOM-σ-z model , two-dimensional current model, WAVEWATCHIII model, SWAN model and wind model are integrating to set up the current and wave models near-shore sea. Finally, with these models, the quasi-operational predictions of tide, wave and storm surge in China near-shore sea and Zhangjiang harbor, and the impact of wave on current and temperature is also simulated.3. By joining satellite remote sensing data and ocean models, A method to calculate topography and flooding in littoral zone is presented, which is already used in Zhanjiang harbor..4. The phenomena from flux decomposing study that suspended sediment and water's transports may be separated is thought as universally possible phenomena. Accordingly, a new idea that the special substance (including seston and solute) and water's long-term transports may be separated is put forward, namely, in the case that the special substance's horizontal convection transport velocity is as same as water's at every tide phase, their tide-averaged horizontal convection transport through vertical section may be different in direction or speed. It is pointed out that tide pumping is the reason why the special substance and water's long-term transports may be separated. It is also pointed out that many substances and water's long-term transports may be universally separated in Estuary fronts, turbidity maximum and fork. Long-term transport velocity of special substance and its decomposed mechanism items are presented as the method for the separation of the special substance and water's long-term transport.5. Based on the simulations from ocean models, the primary separated characters between salinity and water's long-term transport in the salinity front of Changjiang Estuary in winter are given, which presents some new viewpoints different from tradition.