The influence of stratification and nonlocal turbulent production on estuarine turbulence : an assessment of turbulence closure with field observations

View/ Open
Date
2011-01Author
Scully, Malcolm E.
Concept link
Geyer, W. Rockwell
Concept link
Trowbridge, John H.
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/4411As published
https://doi.org/10.1175/2010JPO4470.1DOI
10.1175/2010JPO4470.1Keyword
Turbulence; Estuaries; Kinetic energyAbstract
Field observations of turbulent kinetic energy (TKE), dissipation rate ε, and turbulent length scale demonstrate the impact of both density stratification and nonlocal turbulent production on turbulent momentum flux. The data were collected in a highly stratified salt wedge estuary using the Mobile Array for Sensing Turbulence (MAST). Estimates of the dominant length scale of turbulent motions obtained from the vertical velocity spectra provide field confirmation of the theoretical limitation imposed by either the distance to the boundary or the Ozmidov scale, whichever is smaller. Under boundary-limited conditions, anisotropy generally increases with increasing shear and decreased distance to the boundary. Under Ozmidov-limited conditions, anisotropy increases rapidly when the gradient Richardson number exceeds 0.25. Both boundary-limited and Ozmidov-limited conditions demonstrate significant deviations from a local production–dissipation balance that are largely consistent with simple scaling relationships for the vertical divergence in TKE flux. Both the impact of stratification and deviation from equilibrium turbulence observed in the data are largely consistent with commonly used turbulence closure models that employ “nonequilibrium” stability functions. The data compare most favorably with the nonequilibrium version of the L. H. Kantha and C. A. Clayson stability functions. Not only is this approach more consistent with the observed critical gradient Richardson number of 0.25, but it also accounts for the large deviations from equilibrium turbulence in a manner consistent with the observations.
Description
Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 41 (2011): 166-185, doi:10.1175/2010JPO4470.1.
Collections
Suggested Citation
Journal of Physical Oceanography 41 (2011): 166-185Related items
Showing items related by title, author, creator and subject.
-
Entrainment and mixed layer dynamics of a surface-stress-driven stratiified fluid
Manucharyan, Georgy E.; Caulfield, C. P. (2014-12)We consider experimentally an initially quiescent and linearly stratified fluid with buoyancy frequency NQ in a cylinder subject to surface-stress forcing from a disc of radius R spinning at a constant angular velocity Ω. ... -
Seasonality and buoyancy suppression of turbulence in the Bay of Bengal
Thakur, Ritabrata; Shroyer, Emily L.; Govindarajan, Rama; Farrar, J. Thomas; Weller, Robert A.; Moum, James N. (American Geophysical Union, 2019-04-08)A yearlong record from moored current, temperature, conductivity, and four mixing meters (χpods) in the northernmost international waters of the Bay of Bengal quantifies upper‐ocean turbulent diffusivity of heat (Kt) and ... -
Similarity scaling of turbulence spectra and cospectra in a shallow tidal flow
Walter, Ryan K.; Nidzieko, Nicholas J.; Monismith, Stephen G. (American Geophysical Union, 2011-10-15)Measured turbulence power spectra, cospectra, and ogive curves from a shallow tidal flow were scaled using Monin-Obukhov similarity theory to test the applicability to a generic tidal flow of universal curves found from a ...