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Observation of Near-Inertial Internal Waves on the Continental Slope in the Northwestern South China Sea

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Journal of Ocean University of China 2017年第2期16卷 184-190页

作者： ZHENG Jie tian jiwei LIANG Hui Physical Oceanography Laboratory Ocean University of ChinaQingdao 266100P.R.China

Based on nearly 3 months of moored acoustic Doppler current profiler records on the continental slope in the northwestern South China Sea(SCS) in 2006,this study examines temporal and vertical characteristics of near-inertial internal waves(NIW).Rotary frequency spectrum indicates that motions in the near-inertial frequency are strongly polarized,with clockwise(CW) energy exceeding counterclockwise(CCW) by about a factor of *** analysis exhibits an energy peak exceeding the 95% confidence level at the frequency of local inertial during the passage of typhoon Xangsane(24 September to 4 October).This elevated near-inertial kinetic energy(NIKE) event possesses about a 4 days delay correlation with the time integral of energy flux induced by typhoon,indicating an energy source of *** analysis shows that the upward phase velocity of this event is 3.8 m h^(-1)approximately,corresponding to a vertical wavelength of about 125 m if not taking the redshift of local inertial frequency into *** vertical wavenumber spectrum exhibits the dominance of clockwise-with-depth energy,indicating downward energy propagation and implying a surface energy *** modes suggest that mode 1 plays a dominant role at the growth stage of NIW,whereas major contribution is from higher modes during the penetration of NIKE into the ocean interior.

关键词： South China Sea near-inertial internal waves mooring

Observation of internal tides and near-inertial motions in the upper 450 m layer of the northern South China Sea

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Chinese Science Bulletin 2005年第24期50卷 2890-2895页

作者： LIANG Xinfeng ZHANG Xiaoqian tian jiwei Physical Oceanography Laboratory of Ocean University of China Qingdao 266003 China

Mooring ADCP current observations from Au- gust to November are used to study the barotropic tides, baroclinic tides and near-inertial motions in the upper 450 m layer of the northern South China Sea. The barotropic and baroclinic tides at the mooring station are all dominated by M2, K1, O1, P1, with the barotropic amplitudes being 7.8 cm·s?1, 7.0 cm·s?1, 5.4 cm·s?1 and 3.5 cm·s?1 respectively. The amplitudes of M2, K1, O1, P1 internal tides vary greatly, which are 12―15 cm·s?1 in the thermocline, and then decrease with increasing depth. The amplitude of the barotropic near-iner- tial motions is less than 1 cm·s?1, contributing little to the barotropic currents. However, that of the baroclinic near- inertial motions can be as large as 5 cm·s?1. The inclination of tidal ellipse tends to increase with increasing depth, implying upward propagation of energy, while that of the near-inertial ellipse tends to decrease with increasing depth, implying downward propagation of energy.

关键词：中国南海内潮惯性运动上层海水

Effects of winds,tides and storm surges on ocean surface waves in the Sea of Japan

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Acta Oceanologica Sinica 2007年第3期26卷 9-21页

作者： ZHAO Wei tian jiwei LI Peiliang HOU Yijun College of Physical and Environmental Oceanography Ocean University of ChinaQingdao 266100 China Institute of Oceanology Chinese Academy of SciencesQingdao 266071 China

Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forcing, tides and storm surges on the waves are investigated using a wave model, a high-resolution atmospheric mesoscale model and a hydrodynamic ocean circulation model. Five month-long wave model simulations are inducted to examine the sensitivity of ocean waves to various wind forcing fields, tides and storm surges during January 1997. Compared with observed mean wave parameters, results indicate that the high frequency variability in the surface wind filed has very great effect on wave simulation. Tides and storm surges have a significant impact on the waves in nearshores of the Tsushima-kaihyS, but not for other regions in the Sea of Japan. High spatial and temporal resolution and good quality surface wind products will be crucial for the prediction of surface waves in the JES and other marginal seas, especially near the coastal regions.

关键词： ocean surface wave Sea of Japan winter storm tide storm surge

Observation of small-scale processes over shelf break in the East China Sea

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Chinese Science Bulletin 2005年第24期50卷 2885-2890页

作者： ZHOU Lei tian jiwei ZHANG Xiaoqian Physical Oceanography Laboratory Ocean University of China Qingdao 266003 China

The turbulent dissipation along with tempera- ture and salinity was measured on board R/V Dong Fang Hong 2 over the shelf break of the East China Sea from March 7 to 9, 2004. Applying the Turner angle, it is found that the ‘diffusive’ double diffusion, salt-fingering, and stable stratification coexist in the upper water column of about 50 m. Below that depth, there exists weak salt-fingering. The turbulent dissipation rates are enhanced along the ray paths of M2 internal tides emanating from the shelf break with values ranging from 1.0×10?9 W·kg?1 to 1.2×10?6 W·kg?1. The corresponding diapycnal mixing rates are from 1×10?6 m2·s?1 to 1×10?2 m2·s?1. The spatially averaged mixing rate over the whole observation section is 2.3×10?3 m2·s?1, which is much larger than 1×10?5 m2·s?1 of the background diapy- cnal mixing rate in the open ocean.

关键词：中国东海陆架间断小规模突起两倍扩散率湍流耗散海水盐度温度

Shoaling of the internal solitary waves over the continental shelf of the northern South China Sea

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Acta Oceanologica Sinica 2015年第9期34卷 35-42页

作者： QIAN Hongbao HUANG Xiaodong tian jiwei ZHAO Wei Physical Oceanography Laboratory Ocean University of China The Administrative Centre for China's Agenda 21

The activities of internal solitary waves （ISWs） over the continental shelf of the northern South China Sea （SCS） are of high complexity. In this study, we investigated the spatial-temporal characteristics of the shoaling ISWs over the northern SCS continental shelf using the satellite images and the results of numerical simulation. The examination of the ISW signals in the satellite optical images revealed the existence of three types of iSWs in the region north to the Dongsha Island, namely, mode-1 depression ISW, mode-1 elevation ISW, and mode-2 convex ISW. The geographical distributions of these ISWs were derived from the satellite images. Numerical results exhibited the process of polarity conversion of ISWs, by which mode-1 elevation waves were transformed from the shoaling mode-1 depression waves. The mode-2 convex ISWs generally followed the mode-1 depression ISWs. The numerical results suggested that the interaction of the mode-1 depression ISWs with the up-slope topography locally generated mode-2 ISWs, and such waves of high vertical mode dissipated rapidly during the inshore propagation.

关键词： internal solitary wave nonlinear internal wave South China Sea vertical mode

Mooring observations of internal solitary waves in the deep basin west of Luzon Strait

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Acta Oceanologica Sinica 2014年第3期33卷 82-89页

作者： HUANG Xiaodong ZHAO Wei tian jiwei YANG Qingxuan Physical Oceanography Laboratory Ocean University of China

A total of 137 internal solitary waves （ISWs） are captured during a field experiment conducted in the deep basin west of the Luzon Strait （LS） from March to August, 2010. Mooring observations reveal that a fully developed ISW owns a maximum westward velocity of more than 1.8 m/s and an amplitude of about 200 m. The ISWs in the South China Sea （SCS） are most active in July, which may be due to the strong stratification in summer. Most of the ISW episodes are detected around and after the 1st or 15th lunar day, indicating that the ISW in the SCS is triggered by astronomic tides. Half part of the observed ISWs were detected around 19：00 local time, which can be explained by the fact that type-a ISWs emerged in the evening at roughly the same time each day. The propagation direction of the ISWs and the astronomic tides in the LS show that the area south of the Batan Island is probably the main source region of the type-a ISWs, while the area south of Itbayat Island and south of the Batan Island is likely the main source region of the type-b ISWs observed at the mooring. Moreover, for the resonance of semidiurnal internal tides emitting from the double ridges in the LS, the underwater ridge south of the Itbayat Island and south of the Batan Island is believed to favor the generation of the energetic ISWs.

关键词： internal solitary wave South China Sea observation nonlinear internal wave

Evolution and breaking of a propagating internal wave in stratified ocean

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Acta Oceanologica Sinica 2008年第1期27卷 13-22页

作者： LI Bingrui FAN Haimei tian jiwei SUN Bo ZHANG Zhanhai Physical Oceanography Laboratory Polar Research Institute of China State Oceanic Administration Shanghai 200136 China Institute of Physical Oceanography Ocean University of China Qingdao 266003 China East China Sea Environment Monitoring State Oceanic Administration Shanghai 200137 China

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. 2 N^4ky^-3 （N is the Brunt - Vaisala frequency, k, is the vertical wavenumber）, which is called buoyancy sub-range. 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.

关键词： internal wave breaking pseudo-spectral method buoyancy sub-range Cox number

Estimation of eddy heat transport in the global ocean from Argo data

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Acta Oceanologica Sinica 2014年第1期33卷 42-47页

作者： ZHANG Zhiwei ZHONG Yisen tian jiwei YANG Qingxuan ZHAO Wei Key Laboratory of Physical Oceanography Ocean University of China School of Earth and Atmospheric Sciences Georgia Institute of Technology

The Argo data are used to calculate eddy（turbulence） heat transport（EHT） in the global ocean and analyze its horizontal distribution and vertical *** calculate the EHT by averaging all the v ′,T ′ profiles within each 2 ×2 *** velocity and temperature anomalies are obtained by removing their climatological values from the Argo ＂instantaneous＂ values *** the Student＇s t-test and an error evaluation,we obtained a total of 87% Argo bins with significant depth-integrated EHTs（D-EHTs）.The results reveal a positive-and-negative alternating D-EHT pattern along the western boundary currents（WBC） and Antarctic Circumpolar Current（ACC）.The zonally-integrated D-EHT（ZI-EHT） of the global ocean reaches 0.12 PW in the northern WBC band and –0.38 PW in the ACC band *** strong ZI-EHT across the ACC in the global ocean is mainly caused by the southern Indian *** ZI-EHT in the above two bands accounts for a large portion of the total oceanic heat transport,which may play an important role in regulating the *** analysis of vertical structures of the EHT along the 35 N and 45 S section reveals that the oscillating EHT pattern can reach deep in the northern WBC regions and the Agulhas Return Current（ARC） *** also shows that the strong EHT could reach 600 m in the WBC regions and 1 000 m in the ARC region,with the maximum mainly located between 100 and 400 m *** results would provide useful information for improving the parameterization scheme in models.

关键词： eddy heat transport Argo mesoscale eddy global ocean

Estimation of eddy viscosity on the South China Sea shelf with adjoint assimilation method

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Acta Oceanologica Sinica 2009年第5期28卷 9-16页

作者： ZHANG Yanwei tian jiwei XIE Lingling Physical Oceanography Laboratory Ocean University of China Qingdao 266003 China

The eddy viscosity of the ocean is an important parameter indicating the small-scale mixing process in the oceanic interior water column. Ekman wind-driven current model and adjoint assimilation technique are used to calculate the vertical profiles of eddy viscosity by fitting model results to the observation data. The data used in the paper include observed wind data and ADCP data obtained at Wenchang Oil Rig on the SCS （the South China Sea） shelf in August 2002. Different simulations under different wind conditions are analyzed to explore how the eddy viscosity develops with varying wind field. The results show that the eddy viscosity endured gradual variations in the range of 10^-3 -10^-2 m^2 /s during the periods of wind changes. The mean eddy viscosity undergoing strong wind could rise by about 25% as compared to the value under weak wind.

关键词： the SCS eddy viscosity near-inertial Ekman Model adjoint assimilation