| LI Bingrui,FAN Haimei,TIAN Jiwei,SUN Bo,ZHANG Zhanhai. 2008. Evolution and breaking of a propagating internal wave in stratified ocean. Acta Oceanologica Sinica, (1):13－22 |
| Evolution and breaking of a propagating internal wave in stratified ocean |
| Evolution and breaking of a propagating internal wave in stratified ocean |
| Received:April 06, 2007 Revised:September 15, 2007 |
| DOI： |
| Key words:internal wave breaking pseudo-spectral method buoyancy sub-range Cox number |
| 中文关键词: internal wave breaking pseudo-spectral method buoyancy sub-range Cox number |
| 基金项目:The National Nature Science Foundation of China under contract No.40706002;the National High Technology Development Project of China under contract No.2007AA09Z122. |
| Author Name | Affiliation | E-mail | | LI Bingrui | Physical Oceanography Laboratory, Polar Research Institute of China, State Oceanic Administration, Shanghai 200136, China | Libingru@ipric.gov.cn | | FAN Haimei | East China Sea Environment Monitoring, State Oceanic Administration, Shanghai 200137, China | | | TIAN Jiwei | Institute of Physical Oceanography, Ocean University of China, Qingdao 266003, China | | | SUN Bo | Physical Oceanography Laboratory, Polar Research Institute of China, State Oceanic Administration, Shanghai 200136, China | | | ZHANG Zhanhai | Physical Oceanography Laboratory, Polar Research Institute of China, State Oceanic Administration, Shanghai 200136, China | |
|
| Hits: 839 |
| Download times: 570 |
| Abstract: |
| The evolution and breaking of a propagating internal wave are directly numerically simulated using a pseudo-spectral method. The mechanism of PSI (parametric subharmonic instability) involved in the evolution is testified clearly. It dominates gradually in nonlinear resonant interactions. As a consequence, the energy cascades to a second plant wave packet which has lower frequencies and higher wavenumbers than that of the primary wave. With the growth of this wave packet, wave breaking occurs and causes strongly nonlinear regime, i.e. stratified turbulence. The strong mixing and intermittent of the turbulence can be learned from the evolution of the total energy and kurtosis of vorticity vs. time. Some statistic properties of the stratified turbulence are also analyzed, including the spectra of KE (kinetic energy) and PE (potential energy). The results show that the PE spectra display a wavenumber range scaling as 0.2N4ky-3 (N is the Brunt-Väisälä frequency, ky is the vertical wavenumber), which is called buoyancy subrange. However, the KE spectra cannot satisfy the negative cubic law of vertical wavenumber, which have a much larger downtrend than that of the PE spectra, for the potential energy is transferred more efficiently toward small scales than the kinetic energy. The Cox number of diapycnal diffusivity is also calculated, and it shows a good consistency with the observations and deductions in the ocean interior, during the stage of the stratified turbulence maintaining a fairly active level. |
| 中文摘要: |
| The evolution and breaking of a propagating internal wave are directly numerically simulated using a pseudo-spectral method. The mechanism of PSI (parametric subharmonic instability) involved in the evolution is testified clearly. It dominates gradually in nonlinear resonant interactions. As a consequence, the energy cascades to a second plant wave packet which has lower frequencies and higher wavenumbers than that of the primary wave. With the growth of this wave packet, wave breaking occurs and causes strongly nonlinear regime, i.e. stratified turbulence. The strong mixing and intermittent of the turbulence can be learned from the evolution of the total energy and kurtosis of vorticity vs. time. Some statistic properties of the stratified turbulence are also analyzed, including the spectra of KE (kinetic energy) and PE (potential energy). The results show that the PE spectra display a wavenumber range scaling as 0.2N4ky-3 (N is the Brunt-Väisälä frequency, ky is the vertical wavenumber), which is called buoyancy subrange. However, the KE spectra cannot satisfy the negative cubic law of vertical wavenumber, which have a much larger downtrend than that of the PE spectra, for the potential energy is transferred more efficiently toward small scales than the kinetic energy. The Cox number of diapycnal diffusivity is also calculated, and it shows a good consistency with the observations and deductions in the ocean interior, during the stage of the stratified turbulence maintaining a fairly active level. |
|
HTML
View Full Text
View/Add Comment Download reader |
| Close |
|
|
|
