The Study Of Whitecapping Dissipation Improvement In Wave Model And The Ocean Mixing Process

In the ocean, wave breaking may happen owing to surface wind, wave-wave and wave-current interaction. In deep water, breaking waves mainly happens in the form of wihitecapping, which is essential for sea-air exchanging, surface water mixing in the ocean and wave growth. In the process of typhoon weather, deep-water wave breaking will happen more often, wich have a significant impact on the growth and development of typhoon waves. The research on whitecapping dissipation is one of the important methods to improve the accuracy of the wave model. So the study and analysis of wave breaking characteristics and further improving the calucation of whitecapping dissipation in wave model have significance to calculating typhoon waves and analyze the changing of ocean mixing in the process of typhoon using wave-current coupling model.In summary, this paper mainly carried out the following aspects of the work:1. Based on theory of energy focusing, deep-water breaking waves are generated in the laboratory flume. The characteristic of waves change and the mechanism of energy transfer among frequencies are analyze in detail in the process of waves breaking. The impact of breaking intensity, center frequency, frequency bandwidth and spectral types on wave surface evolution, wave spectrum evolution and characteristic parameters are analyzed in detail. Meanwhile, the dissipation and transfer of energy also are made a detailed analysis in the process of focusing wave propagation. Moreover, the change characteristics of average flow and fluctuating flow caused by wave breaking are analyzed briefly in this paper.2. Based on the characteristics of energy spectrum dissipation and energy transfer owing to wave breaking, the calculation formula of whitecapping dissipation in wave model is improved here and further the accuracy of the wave model on simulating typhoon is improved. When wave breaking happens, the gain and loss of energy among frequencies have especial rules. Based on that characteristics, a new formula of whitecapping dissipation is proposed and the wave model is further improved. Then the advantages and reliability of the improved model are verified by application for the calculation of the typhoon waves.3. Based on the measured and numerical simulation methods, the effects of tidal current, temperature stratification, wind speed change and rotating wind field on the internal mixing of the ocean are analyzed in detail. The mixing coefficients exhibit a significant change with the change of the flow velocity and the vertical distribution is obviously affected by the temperature stratification. The change of wind speed has a significant effect on the strength, depth and response rate of the mixing in the ocean. Under the action of rotating wind field, the distribution of mixing cofficients in the ocean have a certen rules.4. The effects of typhoon process on local flow state, thermohaline structure, and internal mixing are analyzed using wave-current coupling model comprehensively considerating of the South China Sea tide, salinity and temperature fields, and the factors of winds, rainfall, evaporation and heat flux be brought by typhoon. The impact of the typhoon has obvious right dextrality, that is, the intensity, depth and range on the right side of the typhoon path are significantly higher than the left. From the time scale, horizontal scale and vertical scale, the impact of typhoon on local flow state, thermohaline structure, and internal mixing are analyzed.