Mode-one internal tides propagating across a geostrophic current

As a mode-1 internal tide (IT) propagates across a geostrophic current V(x, z), we have investigated the amount of IT energy reflected from the current and the impact of the current on the transmitted wave field. These are quantified by considering the reflection coefficient R and the linear modal e...

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Bibliographic Details
Published inPhysics of fluids (1994) Vol. 33; no. 9
Main Authors He, Yangxin, Lamb, Kevin G.
Format Journal Article
LanguageEnglish
Published Melville American Institute of Physics 01.09.2021
Subjects
Energy conversion
Fluid dynamics
Mathematical analysis
Physics
Propagation modes
Reflectance
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Summary:As a mode-1 internal tide (IT) propagates across a geostrophic current V(x, z), we have investigated the amount of IT energy reflected from the current and the impact of the current on the transmitted wave field. These are quantified by considering the reflection coefficient R and the linear modal energy conversion Pn, where n is the modal number. Here, a linear theory built upon idealized barotropic currents is presented. Fully nonlinear numerical simulations are used for the baroclinic currents. We conclude that the reflection is determined by the horizontal shear of the current Vx through varying the effective frequency feff. The modal energy conversion Pn is determined by the vertical shear of the current Vz, i.e., the horizontal variation of the density ρx as a result of the thermal wind relation. The current can increase R up to around 50%. However, Pn is less than 6% among all our simulations. This indicates that IT can propagate through the current without losing much of its structure and the interaction is mostly linear.
ISSN:1070-6631
1089-7666
DOI:10.1063/5.0064964