| Based on the finite-volume coastal ocean numerical model?FVCOM?,a parameterized internal tide dissipation and the forcing term of the self-attraction and loading?SAL?tide are incorporated into the two-dimensional tidal wave equations to simulate the principal tidal constituents M2,S2,K1 and O1 in the South China Sea?SCS?and its adjacent area.The principal tidal constituents M2,S2,K1 and O1 are simulated simultaneously and compared with the tide station data.Average absolute values of differences between computed and observed harmonic constants of the principal tidal constituents are 4.9 cm,6.2°and 2.3 cm,11.3°and 3.9 cm,6.0°and3.7 cm,6.8°.The comparison of model results with observations indicates that the inclusion of these two terms is capable of improving significantly the simulated results.In order to optimize the coefficient of bottom friction and the dissipation coefficient of internal tide,we choose different combinations of?r,??parameters to carry out numerical experiments,and compare the root mean square error values obtained under various combinations of?r,??.We think that when the minimum corresponding?r,??is the best.In this process,it can be called a cost function.From the previous experience,we can estimate that the bottom friction coefficient r is between 0.001 and 0.004,and the internal tide dissipation factor?is between 6?10-6and 1.2?10-5.We first carry out 49 sets of experiments in this range of?r,??at 0.5×10-3,1×10-6and preliminarily determine the relationship between r and?.By comparing the findings of different experiments,when r and?were 0.0025 and9?10-6,the minimum value is found.After that,we use the encrypted intervals based on this point and carry out many experiments.It is found that when the bottom friction coefficient r is 0.0024,the dissipation coefficient of the internal tide is9.2?10-6,and the minimum value is used in the final simulation.Based on the results of the model,the tidal energy input and dissipation in the study area are calculated and analyzed.The results show that the calculated tidal energy balance,maintaining the South China Sea tidal tidal energy is mainly from the Northwest Pacific through the Luzon Strait.The energy flux of M2,S2,K1 and O1 in the South China Sea is 29.6,3.9,20.4 and 15.5 GW,respectively.The energy input of semidiurnal SAL tides are mostly negative,but the energy input of the diurnal SAL tides are mostly positive.So the SAL tide weakens the semidiurnal tide in the South China Sea and strengthens the diurnal tide in the South China Sea.The tide-generating force also weakens the semidiurnal tide and strengthens the diurnal tide,but its effect is less than the SAL tide.The tidal energy of M2,S2,K1 and O1 in the South China Sea is 7.35,0.95,12.51 and 10.01 GW,respectively,and the energy dissipated by the conversion to internal tide is 12.74,1.72,14.47 and 9.72 GW respectively.Therefore,in the South China Sea,the dissipation of the internal tide is greater than the friction dissipation of the seabed except for the O1 tide.The analysis of tidal energy dissipation shows that the dissipation of bottom friction plays a leading role in the coastal shallow water region,and the internal tide dissipation occurs mainly in the deep water region.The maximum internal tide dissipation occurs in the Luzon Strait,The dissipation in the eastern part of the Luzon Strait beyond the South China Sea is larger than that in the western part of the Luzon Strait.For M2,S2,K1 and O1constituents in the Luzon Strait of the internal tide dissipation value reached 15.85,2.49,22.49,15.25GW. |
PDF Full Text Request