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Modification of turbulent dissipation rates by a deep Southern Ocean eddy
Author(s) -
Sheen K. L.,
Brearley J. A.,
Naveira Garabato A. C.,
Smeed D. A.,
Laurent L. St.,
Meredith M. P.,
Thurnherr A. M.,
Waterman S. N.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063216
Subject(s) - mesoscale meteorology , geology , dissipation , baroclinity , eddy diffusion , internal wave , stratification (seeds) , geophysics , turbulence , mechanics , hydrography , geostrophic wind , turbulence kinetic energy , meteorology , atmospheric sciences , climatology , physics , oceanography , seed dormancy , germination , botany , dormancy , biology , thermodynamics
The impact of a mesoscale eddy on the magnitude and spatial distribution of diapycnal ocean mixing is investigated using a set of hydrographic and microstructure measurements collected in the Southern Ocean. These data sampled a baroclinic, middepth eddy formed during the disintegration of a deep boundary current. Turbulent dissipation is suppressed within the eddy but is elevated by up to an order of magnitude along the upper and lower eddy boundaries. A ray tracing approximation is employed as a heuristic device to elucidate how the internal wave field evolves in the ambient velocity and stratification conditions accompanying the eddy. These calculations are consistent with the observations, suggesting reflection of internal wave energy from the eddy center and enhanced breaking through critical layer processes along the eddy boundaries. These results have important implications for understanding where and how internal wave energy is dissipated in the presence of energetic deep geostrophic flows.