Assessment of fine-scale parameterizations of turbulent dissipation rates near mixing hotspots in the deep ocean

作者：Hibiya Toshiyuki^*; Furuichi Naoki; Robertson Robin

来源：Geophysical Research Letters, 2012, 39(24): L24601.

DOI：10.1029/2012GL054068

Shear-based and/or strain-based fine-scale parameterizations of turbulent dissipation rates in the deep ocean become erroneous near topographic features where internal wave spectra deviate from Garrett-Munk (GM). Although the Gregg-Henyey-Polzin (GHP) parameterization incorporates this spectral deviation, the applicability remains uncertain. We evaluate %26quot;alpha%26quot; and %26quot;beta%26quot; representing the local internal wave energy in the high frequency (2f %26lt; omega %26lt; N) and low frequency (f %26lt; omega %26lt; 2f) bands, respectively, scaled by their corresponding values in GM using fine-scale vertical shear and strain simultaneously measured near mixing hotspots. The local internal wave spectra are biased toward higher frequencies (alpha/beta %26gt;%26gt; 1) over rough bathymetry where high frequency internal waves are generated, whereas they are biased toward lower frequencies (alpha/beta %26lt;%26lt; 1) at latitudes where high vertical wavenumber, near-inertial shears are created by parametric subharmonic instabilities. Compared with the shear-based and/or strain-based parameterizations, GHP more accurately estimates turbulent dissipation rates by compensating for deviations from GM. Citation: Hibiya, T., N. Furuichi, and R. Robertson (2012), Assessment of fine-scale parameterizations of turbulent dissipation rates near mixing hotspots in the deep ocean, Geophys. Res. Lett., 39, L24601, doi: 10.1029/2012GL054068.

• 出版日期2012-12-18