A Multiwavenumber Theory for Eddy Diffusivities and Its Application to the Southeast Pacific (DIMES) Region

Journal Article · Wed Jul 01 00:00:00 EDT 2015 · Journal of Physical Oceanography

DOI:https://doi.org/10.1175/jpo-d-14-0229.1· OSTI ID:1565388

Chen, Ru ^[1]; Gille, Sarah T. ^[1]; McClean, Julie L. ^[1]; Flierl, Glenn R. ^[2]; Griesel, Alexa ^[3]

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1. Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
3. Univ. of Hamburg, Hamburg (Germany)

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 ^K₀° 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). Finally, both the single-wavenumber and multiwavenumber theories represent the horizontal structures of cross-stream diffusivities, which resemble the eddy kinetic energy patterns.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Univ. of California, San Diego, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: OCE0960914; TG-OCE100001
• OSTI ID: 1565388
• Journal Information: Journal of Physical Oceanography, Vol. 45, Issue 7; ISSN 0022-3670
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Oceanography