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dc.contributor.advisorAnis, Ayal
dc.contributor.advisorZhao, Dongliang
dc.creatorZhang, Zheng
dc.date.accessioned2013-12-16T19:59:39Z
dc.date.available2015-08-01T05:48:23Z
dc.date.created2013-08
dc.date.issued2013-05-24
dc.date.submittedAugust 2013
dc.identifier.urihttps://hdl.handle.net/1969.1/151031
dc.description.abstractTurbulent dynamics at two sites (C and D) in a hypoxic zone on the Texas- Louisiana continental shelf were studied by investigating turbulence quantities i.e. turbulence kinetic energy (TKE), dissipation rate of TKE (E), Reynolds stress (τ ), dissipation rate of temperature variance (χ), eddy diffusivity of temperature (ν't), and eddy diffusivity of density (ν'p). Numerical models were also applied to test their capability of simulating these turbulence quantities. At site D, TKE, E, and τ were calculated from velocity measurements in the bot- tom boundary layer (BBL), using the Kolmogorov’s -5/3 law in the inertial subrange of energy spectra of vertical velocity fluctuations in each burst measurement. Four second-moment turbulence closure models were applied for turbulence simulations, and modeled turbulence quantities were found to be consistent with those observed. It was found from inter-model comparisons that models with the stability functions of Schumann and Gerz predicted higher values of turbulence quantities than those of Cheng in the mid layer, which might be due to that the former stability functions are not sensitive to buoyancy. At site C, χ, E, v’t, and ν’p were calculated from profile measurements throughout the water column, and showed high turbulence level in the surface boundary layer and BBL, as well as in the mid layer where shear stress was induced by advected non-local water above a hypoxic layer. The relatively high dissolved oxygen in the non-local water resulted in upward and downward turbulent oxygen fluxes, and the bottom hypoxia will deform due to turbulence in 7.11 days. Two of the four models in the study at site D were implemented, and results showed that turbulence energy resulting from the non-local water was not well reproduced. We attribute this to the lack of high-resolution velocity measurements for simulations. Model results agreed with observations only for χ and E simulated from the model with the stability function of Cheng in the BBL. Discrepancies between model and observational results lead to the following conclusions: 1) the stability functions of Schumann and Gerz are too simple to represent the turbulent dynamics in stratified mid layers; 2) detailed velocity profiles measurements are required for models to accurately predict turbulence quantities. Missing such observations would result in underestimation,en
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.subjectturbulenceen
dc.subjectcontinental shelfen
dc.subjectbottom boundary layeren
dc.subjecttwo-equation turbulence modelsen
dc.subjectsecond-moment turbulence closuresen
dc.subjectstability functionsen
dc.subjectturbulent oxygen fluxen
dc.subjectbottom hypoxiaen
dc.titleObservational and Numerical Modeling Studies of Turbulence on the Texas-Louisiana Continental Shelfen
dc.typeThesisen
thesis.degree.departmentOceanographyen
thesis.degree.disciplineOceanographyen
thesis.degree.grantorTexas A & M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.contributor.committeeMemberKlein, Douglas J
dc.contributor.committeeMemberStoessel, Achim
dc.type.materialtexten
dc.date.updated2013-12-16T19:59:39Z
local.embargo.terms2015-08-01


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