Breaking of internal waves and turbulent dissipation in an anticyclonic mode Water Eddy
A 4-month glider mission was analyzed to assess turbulent dissipation in an anticyclonic eddy at the western boundary of the subtropical North Atlantic. The eddy (radius ≈ 60 km) had a core of low potential vorticity between 100 and 450 m, with maximum radial velocities of 0.5 m s -1 and Rossby numb...
Published in: | Journal of Physical Oceanography |
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Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2020
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Subjects: | |
Online Access: | https://eprints.soton.ac.uk/441026/ https://eprints.soton.ac.uk/441026/1/jpo_d_19_0168.1.pdf https://eprints.soton.ac.uk/441026/2/jpod190168.pdf |
Summary: | A 4-month glider mission was analyzed to assess turbulent dissipation in an anticyclonic eddy at the western boundary of the subtropical North Atlantic. The eddy (radius ≈ 60 km) had a core of low potential vorticity between 100 and 450 m, with maximum radial velocities of 0.5 m s -1 and Rossby number ≈-0.1. Turbulent dissipation was inferred from vertical water velocities derived from the glider flight model. Dissipation was suppressed in the eddy core (ε ≈ 5 ☓ 10 -10 Wkg -1 ) and enhanced below it (>10 -9 Wkg -1 ). Elevated dissipation was coincident with quasiperiodic structures in the vertical velocity and pressure perturbations, suggesting internal waves as the drivers of dissipation. A heuristic ray-tracing approximation was used to investigate the wave–eddy interactions leading to turbulent dissipation. Ray-tracing simulations were consistent with two types of wave–eddy interactions that may induce dissipation: the trapping of near-inertial wave energy by the eddy’s relative vorticity, or the entry of an internal tide (generated at the nearby continental slope) to a critical layer in the eddy shear. The latter scenario suggests that the intense mesoscale field characterizing the western boundaries of ocean basins might act as a ‘‘leaky wall’’ controlling the propagation of internal tides into the basin’s interior. |
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