The Latitudinal Dependence of Shear and Mixing in the Pacific Transiting the Critical Latitude for PSI

TitleThe Latitudinal Dependence of Shear and Mixing in the Pacific Transiting the Critical Latitude for PSI
Publication TypeJournal Article
Year of Publication2013
AuthorsMacKinnon JA, Alford MH, Pinkel R, Klymak J, Zhao Z
JournalJournal of Physical Oceanography
Volume43
Pagination3-16
Date Published2013/01
ISBN Number0022-3670
Abstract

Turbulent mixing rates are inferred from measurements spanning 25°–37°N in the Pacific Ocean. The observations were made as part of the Internal Waves Across the Pacific experiment, designed to investigate the long-range fate of the low-mode internal tide propagating north from Hawaii. Previous and companion results argue that, near a critical latitude of 29°N, the internal tide loses energy to high-mode near-inertial motions through parametric subharmonic instability. Here, the authors estimate mixing from several variations of the finescale shear–strain parameterization, as well as Thorpe-scale analysis of overturns. Though all estimated diffusivities are modest in magnitude, average diffusivity in the top kilometer shows a factor of 2–4 elevation near and equatorward of 29°N. However, given intrinsic uncertainty and the strong temporal variability of diffusivity observed in long mooring records, the meridional mixing pattern is found to be near the edge of statistical significance.

DOI10.1175/JPO-D-11-0107.1
Integrated Research Themes: 
Student Publication: 
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