Open AccessInternal Tidal Modal Ray Refraction and Energy Ducting in Baroclinic Gulf Stream Currents
Author(s) -
Timothy F. Duda,
YingTsong Lin,
Maarten C. Buijsman,
Arthur E. Newhall
Publication year - 2018
Publication title -
journal of physical oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 143
eISSN - 1520-0485
pISSN - 0022-3670
DOI - 10.1175/jpo-d-18-0031.1
Subject(s) - baroclinity , barotropic fluid , energy flux , atmospheric duct , internal wave , wavenumber , geology , gulf stream , mesoscale meteorology , geophysics , refraction , tidal power , physics , flux (metallurgy) , meteorology , oceanography , optics , ecology , materials science , astronomy , atmosphere (unit) , metallurgy , biology
Upstream mean semidiurnal internal tidal energy flux has been found in the Gulf Stream in hydrodynamical model simulations of the Atlantic Ocean. A major source of the energy in the simulations is the south edge of Georges Bank, where strong and resonant Gulf of Maine tidal currents are found. An explanation of the flux pattern within the Gulf Stream is that internal wave modal rays can be strongly redirected by baroclinic currents and even trapped (ducted) by current jets that feature strong velocities above the thermocline that are directed counter to the modal wavenumber vector (i.e., when the waves travel upstream). This ducting behavior is analyzed and explained here with ray-based wave propagation studies for internal wave modes with anisotropic wavenumbers, as occur in mesoscale background flow fields. Two primary analysis tools are introduced and then used to analyze the strong refraction and ducting: the generalized Jones equation governing modal properties and ray equations that are suitable for studying waves with anisotropic wavenumbers.