On the generation and evolution of nonlinear internal waves in the South China Sea

被引:148
作者
Buijsman, M. C. [1 ]
Kanarska, Y. [2 ]
McWilliams, J. C. [1 ]
机构
[1] Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA 90095 USA
[2] Lawrence Livermore Natl Lab, Livermore, CA 94550 USA
关键词
OCEANIC MODELING SYSTEM; TIDAL FLOW; SOLITARY WAVES; LEE WAVES; LUZON STRAIT; TIDES; TOPOGRAPHY; RIDGE; DISSIPATION; PROPAGATION;
D O I
10.1029/2009JC005275
中图分类号
P7 [海洋学];
学科分类号
0707 ;
摘要
The nonhydrostatic Regional Ocean Modeling System is applied to the nonlinear internal waves, or solitons, that are generated at the Luzon ridge in the South China Sea. The Luzon ridge near the Batan islands is represented by an idealized ridge with a height of 2.6 km on a flat bottom. Model runs are performed for various ridge shapes and (a) symmetric tidal forcings. The model is in the mixed tidal lee wave regime. The barotropic tide over the ridge generates first-mode waves through the internal tide release mechanism. Westward-traveling solitons emerge from these first-mode waves through nonlinear steepening. In the internal tide release mechanism, asymmetric tides with strong eastward currents can generate strong westward solitons. The eastward current creates an elevation wave with a higher energy density west of the ridge, and as soon as the current slackens, the wave is released westward. On its backslope strong solitons develop. The energy density is further enhanced by nonlinearities, such as differences in phase speeds and energy fluxes related to lee waves. A modal and harmonic decomposition shows the generation of vertical modes and higher temporal harmonics and indicates significant wave-wave interaction (e.g., triads). In the mixed tidal lee wave regime, more energy is contained in the first mode compared to the higher modes. Hence, linear internal tide beams are less well defined and strong solitons develop.
引用
收藏
页数:17
相关论文
共 56 条
[1]  
Antonov J.I., 2006, SALINITY NOAA ATLAS, V62
[2]  
Antonov J.I., 2006, WORLD OCEAN ATLAS 20, V2
[3]  
Apel JR, 2003, J PHYS OCEANOGR, V33, P2247, DOI 10.1175/1520-0485(2003)033<2247:ANAMFI>2.0.CO
[4]  
2
[5]   UPSTREAM BLOCKING AND AIR-FLOW OVER MOUNTAINS [J].
BAINES, PG .
ANNUAL REVIEW OF FLUID MECHANICS, 1987, 19 :75-97
[6]  
Balmforth NJ, 2002, J PHYS OCEANOGR, V32, P2900, DOI 10.1175/1520-0485(2002)032<2900:TCBST>2.0.CO
[7]  
2
[8]   LEE WAVES IN STRATIFIED FLOWS WITH SIMPLE HARMONIC TIME-DEPENDENCE [J].
BELL, TH .
JOURNAL OF FLUID MECHANICS, 1975, 67 (FEB25) :705-722
[9]   ON MEAN MOTION INDUCED BY INTERNAL GRAVITY WAVES [J].
BRETHERTON, FP .
JOURNAL OF FLUID MECHANICS, 1969, 36 :785-+
[10]   A numerical study of the generation and propagation of internal solitary waves in the Luzon Strait [J].
Cai, SQ ;
Long, XM ;
Gan, ZJ .
OCEANOLOGICA ACTA, 2002, 25 (02) :51-60