Continuous observation in late April 2005 on the northwestern shelf of the South China Sea reveals vigorous strong currents, the maximum velocity of which exceeds 3.8 m/s. The strong currents occurred around spring ti...Continuous observation in late April 2005 on the northwestern shelf of the South China Sea reveals vigorous strong currents, the maximum velocity of which exceeds 3.8 m/s. The strong currents occurred around spring tide period, when the internal tide waves were also expected to be vigorous. Analysis shows that the major peaks of the current power spectrum are in low frequency band. Using a numerical method applied to the actual ocean stratification, we find that the amplitude profiles of the strong current are similar to that of the currents induced by some low-mode internal waves （at diurnal or semi-diurnal frequency）. It indicates that the temporal and spatial features of strong currents were possibly induced by low frequency internal waves.展开更多
We investigated the vertical distribution of current velocity data of the entire water column at a site on the continental shelf of the northern South China Sea(SCS) from August 4 to September 6,2007,and found that th...We investigated the vertical distribution of current velocity data of the entire water column at a site on the continental shelf of the northern South China Sea(SCS) from August 4 to September 6,2007,and found that the characteristics of barotropic and baroclinic tides are mainly diurnal.During the observation period,we also estimated the mixing before and after the passage of Typhoon Pabuk.We found that the internal-wave-scale dissipation rate,the turbulent dissipation rate,and the mixing rate in every water layer increased by about an order of magnitude after the typhoon passage.We analyzed a case of abrupt strong current and calculated the mixing rate before,during,and after the typhoon event.The results show that the internal-wave-scale dissipation rate and the mixing rate in every water layer increased by about two orders of magnitude during the event,while the turbulent dissipation rate increased by about an order of magnitude.Passage of the abrupt strong current could also have increased the mixing rate of affected seawater by more than an order of magnitude.However,the passage of the typhoon differed in that there was an increase in mixing only in the lower layer where the abrupt strong current was particularly strong.The variation of the mixing rate may help us to understand the effects of typhoons and abrupt strong currents on the mixing of seawater.展开更多
基金the National Natural Science Foundation of China under contract Nos 41006018 and 40730842The National Basic Research Program(973 Program)of China under contract No.2011CB403502+2 种基金the National High Technology Research and Development Program(863 Program)of China under contract No.2008AA09A402Open Fund of the Key Laboratory of Ocean Circulation and WavesChinese Academy of Sciences under contract No.KLOCAW0905
文摘Continuous observation in late April 2005 on the northwestern shelf of the South China Sea reveals vigorous strong currents, the maximum velocity of which exceeds 3.8 m/s. The strong currents occurred around spring tide period, when the internal tide waves were also expected to be vigorous. Analysis shows that the major peaks of the current power spectrum are in low frequency band. Using a numerical method applied to the actual ocean stratification, we find that the amplitude profiles of the strong current are similar to that of the currents induced by some low-mode internal waves （at diurnal or semi-diurnal frequency）. It indicates that the temporal and spatial features of strong currents were possibly induced by low frequency internal waves.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-03)China National Funds for Distinguished Young Scientists, National High Technology Research and Development Program of China (863 Program) (Nos.2008AA09Z112,2008AA09A402)+1 种基金National Natural Science Foundation of China (No.40676021)the Chinese Oceanic Association (No.DYXM-115-02-4-02)
文摘We investigated the vertical distribution of current velocity data of the entire water column at a site on the continental shelf of the northern South China Sea(SCS) from August 4 to September 6,2007,and found that the characteristics of barotropic and baroclinic tides are mainly diurnal.During the observation period,we also estimated the mixing before and after the passage of Typhoon Pabuk.We found that the internal-wave-scale dissipation rate,the turbulent dissipation rate,and the mixing rate in every water layer increased by about an order of magnitude after the typhoon passage.We analyzed a case of abrupt strong current and calculated the mixing rate before,during,and after the typhoon event.The results show that the internal-wave-scale dissipation rate and the mixing rate in every water layer increased by about two orders of magnitude during the event,while the turbulent dissipation rate increased by about an order of magnitude.Passage of the abrupt strong current could also have increased the mixing rate of affected seawater by more than an order of magnitude.However,the passage of the typhoon differed in that there was an increase in mixing only in the lower layer where the abrupt strong current was particularly strong.The variation of the mixing rate may help us to understand the effects of typhoons and abrupt strong currents on the mixing of seawater.
