南海西北部半日内潮参量次谐频不稳定生成的近惯性波研究

为了研究非临界纬度上参量次谐频不稳定(parametric subharmonic instability,PSI)过程生成的近惯性波(near-inertial wave,NIW),本文基于国家重点研发项目的 准实时传输深海潜标资料,对内波速度谱、近惯性流速和动能、D2-f(半日频减惯性频)流速和动能、半日内潮流速和...

SEMIDIURAL TIDE PARAMETETRIC SUBHARMONIC INSTABILITY INDUCED NEAR-INERTIAL WAVES IN NORTHWESTERN SOUTH CHINA SEA

In order to study the near-inertial wave(NIW) generated by the parametric subharmonic instability(PSI)process at non-critical latitudes, this paper examines the internal wave velocity spectrum, near inertial velocity and kinetic energy, D₂-f(semidiurnal frequency minus inertial frequency) velocity and kinetic energy, semidiurnal tidal velocity and kinetic energy, and the time variation of turbulent mixing based on the data of quasi-real-time transmission subsurface mooring system. The slab model and bicoherence spectrum analysis show that the non-wind-generated near inertial waves appearing in the upper ocean are generated by the PSI of semidiurnal internal tides. The PSI not only generates diurnal internal waves, but also produces inertial frequency and D₂-f motions in the non-critical latitudes of the Northwestern Slope of the South China Sea. At some depth where the PSI process is discernible, the near-inertial energy generated by the PSI is equivalent to the diurnal tidal energy, and the D₂-f energy is equivalent to the semidiurnal tidal energy. In addition,significant PSI processes usually occur during strong semidiurnal movements. The results of the fine-scale parameterization method shows that the mixing is obviously enhanced during the PSI process, but the increase is moderate.