A Multiwavenumber Theory for Eddy Diffusivities and Its Application to the Southeast Pacific (DIMES) Region
Name
Chen-2015-A multiwavenumber th.pdf
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4.91 MB
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Author(s)
Gille, Sarah T.
McClean, Julie L.
Griesel, Alexa
Flierl, Glenn Richard
Chen, Ru, Ph. D. Massachusetts Institute of Technology
Date Issued
July 2015
Journal
Journal of Physical Oceanography
Publisher
American Meteorological Society
Citation
Chen, Ru, Sarah T. Gille, Julie L. McClean, Glenn R. Flierl, and Alexa Griesel. “A Multiwavenumber Theory for Eddy Diffusivities and Its Application to the Southeast Pacific (DIMES) Region.” Journal of Physical Oceanography 45, no. 7 (July 2015): 1877–1896. © 2015 American Meteorological Society
Version
Final published version
Abstract
A multiwavenumber theory is formulated to represent eddy diffusivities. It expands on earlier single-wavenumber theories and includes the wide range of wavenumbers encompassed in eddy motions. In the limiting case in which ocean eddies are only composed of a single wavenumber, the multiwavenumber theory is equivalent to the single-wavenumber theory and both show mixing suppression by the eddy propagation relative to the mean flow. The multiwavenumber theory was tested in a region of the Southern Ocean (70°–45°S, 110°–20°W) that covers the Drake Passage and includes the tracer/float release locations during the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). Cross-stream eddy diffusivities and mixing lengths were estimated in this region from the single-wavenumber theory, from the multiwavenumber theory, and from floats deployed in a global k[subscript 0]° Parallel Ocean Program (POP) simulation. Compared to the single-wavenumber theory, the horizontal structures of cross-stream mixing lengths from the multiwavenumber theory agree better with the simulated float-based estimates at almost all depth levels. The multiwavenumber theory better represents the vertical structure of cross-stream mixing lengths both inside and outside the Antarctica Circumpolar Current (ACC). Both the single-wavenumber and multiwavenumber theories represent the horizontal structures of cross-stream diffusivities, which resemble the eddy kinetic energy patterns.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1175/JPO-D-14-0229.1
