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A near‐inertial mode observed within a Gulf Stream warm‐core ring
Author(s) -
Joyce Terrence M.,
Toole John M.,
Klein Patrice,
Thomas Leif N.
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/jgrc.20141
Subject(s) - baroclinity , pycnocline , geology , eddy , inertial wave , acoustic doppler current profiler , nautical mile , vortex , ring (chemistry) , geophysics , physics , oceanography , mechanics , current (fluid) , turbulence , wave propagation , optics , mechanical wave , longitudinal wave , chemistry , organic chemistry
Layering of ocean velocity “fine structure” has been coherently observed across the entire extent of a Gulf Stream warm‐core ring using a shipboard acoustic Doppler current profiler system in September 2009 and independently sampled as the ring transited a moored array. Lines of constant velocity phase generally followed isopycnals as they deepened within the ring center. We also observed a clear separation of the vertical structure of the flows associated with the ring (of order 0.5 m/s) with the shorter (200 m) and less energetic (~0.2 m/s) flows of the velocity fine structure, which was further observed to rotate clockwise with increasing depth, consistent with downward propagating near‐inertial waves (NIWs). Observations are consistent with a ring‐scale NIW packet, probably wind forced, that shows enhanced NIW energy within the sloping pycnocline at depths of 300–700 m. Evidence of wind‐forced NIWs within anticylonic eddies in a numerical simulation shows some similar features to our observations, which we try to understand physically with basic WKB‐type wave/current dynamics along the lines of previously published work and a new calculation of NIW trapping within an isolated, baroclinic vortex.