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Effects of Finite Amplitude Bottom Topography on Ocean Variability

Title: Effects of Finite Amplitude Bottom Topography on Ocean Variability.
Name(s): Leonov, Dmitri A., author
Dewar, William K., professor directing thesis
Navon, Ionel Michael, outside committee member
Clarke, Allan J., committee member
Landing, William M., committee member
McWilliams, James C., committee member
Nof, Doron, committee member
Stern, Melvin E., committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2005
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The wind-driven oceanic circulation in the presence of bottom topography that isopycnals intersect is examined in an idealized setting. A modified quasi-geostrophic (QG) model has been designed and implemented. The model allows staircase bottom topography: topographic breaks decompose the lateral domain into subdomains consisting of fixed numbers of layers. Topographic shelves are placed within small (order Rossby number) vertical distances from the undisturbed layer interfaces. Each shelf can have topographic variations of the same scale. An elliptic solver inverting potential vorticity into geostrophic stream functions was designed based on the Capacitance matrix method. Solutions are matched at the topographic breaks by adding fictitious potential vorticity sources. The model has been tested against the problem of trapped topographic waves over a cliff. The results obtained for small-steepness disturbances agree with a weakly non-linear theory developed by Dewar and Leonov. Steeper disturbances break in a way that favors on shelf eddy detachment and transport of undiluted properties onto the shelf. The model has been further applied to the basin-scale wind-driven circulation problem in a 3-layer configuration with a continental shelf in the western part of the domain. Double-gyre wind forcing has been considered. The topographic shelves are responsible for dynamics absent in classical idealized eddy resolving QG models which have been the preferred numerical tool for the study of low frequency intrinsic ocean variability. The top-layer flow interacts with the shelf topography by means of vortex tube stretching and vorticity dissipation due to bottom drag. This mechanism reduces the role of horizontal friction as a controlling factor in the dynamics.The results obtained for different parameter regimes (free-slip, no-slip boundary condition, different values of the viscosity) show reduced sensitivity to the type of dynamic boundary condition, compared to classical results. The intrinsic variability of the flow is affected by the new mechanism of on- and off shelf transport of potential vorticity. The role of horizontal friction is again reduced, as shown by the modeling results. Spatiotemporal patterns of the variability have been analyzed. Most of the patterns are insensitive to the type of boundary condition (free-slip vs. no-slip), and qualitatively resemble classical no-slip results.
Identifier: FSU_migr_etd-3121 (IID)
Submitted Note: A Dissertation submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Summer Semester, 2005.
Date of Defense: May 31, 2005.
Keywords: Wind-Driven Circulation, Decadal Climate Variability, Ocean Intrinsic Variability, Finite Topography, Trapped Topographic Waves
Bibliography Note: Includes bibliographical references.
Advisory Committee: William K. Dewar, Professor Directing Thesis; Ionel Michael Navon, Outside Committee Member; Allan J. Clarke, Committee Member; William M. Landing, Committee Member; James C. McWilliams, Committee Member; Doron Nof, Committee Member; Melvin E. Stern, Committee Member.
Subject(s): Oceanography
Atmospheric sciences
Persistent Link to This Record:
Owner Institution: FSU

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Leonov, D. A. (2005). Effects of Finite Amplitude Bottom Topography on Ocean Variability. Retrieved from