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Density stratification influences on generation of different modes internal solitary waves
Author(s) -
Chen ZhiWu,
Xie Jieshuo,
Wang Dongxiao,
Zhan JieMin,
Xu Jiexin,
Cai Shuqun
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010069
Subject(s) - pycnocline , mode (computer interface) , stratification (seeds) , internal tide , baroclinity , internal wave , nonlinear system , geology , oceanography , mechanics , physics , biology , seed dormancy , botany , germination , quantum mechanics , dormancy , computer science , operating system
An ideal tide‐topography interaction model is utilized for studying the influence of density stratification (pycnocline depth d , thickness δ , and the density difference Δ ρ aacross the pycnocline) on nonlinear disintegration of the first (mode‐1) and second (mode‐2) baroclinic mode internal tides into internal solitary waves (ISWs). The solution methods include weakly nonlinear analysis and fully nonlinear simulation. It is found that as d increases, even though the energy flux into mode‐1 internal tides is always larger than that into mode‐2 ones at generation, mode‐2 ISWs emerge and mode‐1 ISWs are suppressed. As δ increases, the total energy conversion and the fluxes into both mode‐1 and mode‐2 tides all increase first and then decrease. During propagation, a thick pycnocline is actually not favorable for the emergence of mode‐2 ISWs, and the simulated well‐developed mode‐2 ISWs for a pycnocline of intermediate thickness are due to the tide generation process. As Δ ρ aincreases, the total conversion and the fluxes into both mode‐1 and mode‐2 tides all increase almost linearly. Even though the flux into mode‐1 tides is always larger than that into mode‐2 ones at generation, mode‐1 tides cannot disintegrate but mode‐2 ISWs develop very well. During propagation, Δ ρ ahas no influence on the generation of ISWs. The present work systematically investigates the influence of density stratification on formation of ISWs by considering both internal tide generation and propagation processes.