Background current a ects the internal wave structure of the northern South China Sea  

Background current affects the internal wave structure of the northern South China Sea

作　　者：Xiaomin Long Danpeng Dong ShenganWang 

机构地区：[1]LED, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China

出　　处：《Progress in Natural Science:Materials International》2008年第5期585-589,共5页自然科学进展·国际材料（英文版）

基　　金：This work was supported by the National Hi-Tech Program(No．2008AA09Z112)；the National Natural Foundation of China(Grant No．40676021 and 40576014)；the Guangdong Province of China(No．2007B030200004).

摘　　要：The internal wave modal equations are solved with the consideration of background currents. Analytical and numerical solutions of some specific examples, including observations in the northern South China Sea （SCS）, are obtained to investigate the effect of back- ground current on internal wave vertical structure. The effects of current shear and curvature on internal wave vertical structure are eval- uated separately. It is found that the phase speed and wave structure are modified by background currents, the current shear has little effect on wave structure, whilst the current curvature could have a strong impact on the wave structure. The extent of the effect by the current curvature on the wave structure depends on the magnitudes of current curvature, relative wave speed, and buoyancy frequency, sometimes the effect by the current curvature may even cause the wave to attenuate severely with depth. A new method to obtain the real eigenfunction with depth in the case that the waves become evanescent is also put forward. It is shown that the residual tidal current in the northern SCS is strong enough to cause the wave to attenuate severely at the uooer laver.The internal wave modal equations are solved with the consideration of background currents. Analytical and numerical solutions of some speci c examples, including observations in the northern South China Sea (SCS), are obtained to investigate the e ect of back- ground current on internal wave vertical structure. The e ects of current shear and curvature on internal wave vertical structure are eval- uated separately. It is found that the phase speed and wave structure are modi ed by background currents, the current shear has little e ect on wave structure, whilst the current curvature could have a strong impact on the wave structure. The extent of the e ect by the current curvature on the wave structure depends on the magnitudes of current curvature, relative wave speed, and buoyancy frequency, sometimes the e ect by the current curvature may even cause the wave to attenuate severely with depth. A new method to obtain the real eigenfunction with depth in the case that the waves become evanescent is also put forward. It is shown that the residual tidal current in the northern SCS is strong enough to cause the wave to attenuate severely at the upper layer.

关 键 词：Internal waves Wave mode Current shear Current curvature Numerical method South China Sea 

分 类 号：TM619[电气工程—电力系统及自动化]