• Login
    About WHOAS
    View Item 
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of WHOASCommunities & CollectionsBy Issue DateAuthorsTitlesKeywordsThis CollectionBy Issue DateAuthorsTitlesKeywords

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Studies of lateral dispersion in the ocean

    Thumbnail
    View/Open
    Sundermeyer_Thesis (77.85Mb)
    Date
    1998-09
    Author
    Sundermeyer, Miles A.  Concept link
    Metadata
    Show full item record
    Citable URI
    https://hdl.handle.net/1912/8852
    DOI
    10.1575/1912/8852
    Keyword
     Oceanic mixing; Ocean-atmosphere interaction; Tracers 
    Abstract
    This thesis is written in two parts. The first part deals with the problem oflateral dispersion due to mesoscale eddies in the open ocean, and the interaction between the mesoscale strain and horizontal diffusion on spatial scales less than 10 km. The second and major part examines lateral dispersion over the continental shelf on scales of 100 m to 10 km and over time scales of 1- 5 days. PART I: Lateral Dispersion and the North Atlantic Tracer Release Experiment Mixing and stirring of Lagrangian particles and a passive tracer were studied by comparison of float and tracer observations from the North Atlantic Tracer Release Experiment. Statistics computed from the NATRE floats were found to be similar to those estimated by Ledwell et al. (1998) from the tracer dispersion. Mean velocities computed from the floats were (u, v) = ( -1.2±0.3, -0.9±0.2) em s-1 for the (zonal, meridional) components, and large-scale effective eddy diffusivities were (KP. 11 , K:e 22 ) = (1.5±0. 7, 0. 7±0.4) x 103 m2 s-1 . The NATRE observations were used to evaluate theoretical models of tracer and particle dispersal. The tracer dispersion observed by Ledwell et al. (1998) was consistent with an exponential growth phase for about the first 6 months and a linear growth at larger times. A numerical model of mesoscale turbulence that was calibrated with float statistics also showed an exponential growth phase of tracer and a reduced growth for longer times. Numerical results further show that Garrett's (1983) theory, relating the effective small-scale diffusivity to the rms strain rate and tracer streak width, requires a scale factor of 2 when the observed growth rate of streak length is used as a measure of the strain rate. This scale factor will be different for different measures of the strain rate, and may also be affected by temporal and spatial variations in the mesoscale strain field. PART II: Lateral Dispersion over the New England Continental Shelf Lateral dispersion over the continental shelf was examined using dye studies of the Coastal Mixing and Optics (CMO) program. Four experiments performed at intermediate depths and lasting 3 to 5 days were examined. In some cases, the dye patches remained fairly homogeneous both vertically and horizontally throughout an experiment. In other cases, significant patchiness was observed on scales ranging from 2- 10 m vertically and a few hundred meters to a few kilometers horizontally. The observations also showed that the dye distributions were significantly influenced by shearing and straining on scales of 5- 10 m in the vertical and 1- 10 km in the horizontal. Superimposed on these larger-scale distortions were simultaneous increases in the horizontal second moments of the dye patches, with corresponding horizontal diffusivities based on a Fickian diffusion model of 0.3 to 4.9 m2 s-1 . Analysis of the dye data in concert with shear estimates from shipboard ADCP observations showed that the existing paradigms of shear dispersion and dispersion by interleaving water-masses can not account for the observed diffusive spreading of the dye patches. This result suggests that some other mechanisms provided an additional diffusivity of order 0.15 to 4.0 m2 s-1 . An alternative mechanism, dispersion by vortical motions caused by the relaxation of diapycnal mixing events, was proposed which could explain the observed dispersion in some cases. Order-of-magnitude estimates of the effective lateral dispersion due to vortical motions showed that this mechanism could account for effective horizontal diffusivities of order 0.01 to 1.1 m2 s-1 . The upper range of these estimates were within the range required by the observations for two of the four experiments examined.
    Description
    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1998
    Collections
    • Physical Oceanography (PO)
    • WHOI Theses
    Suggested Citation
    Thesis: Sundermeyer, Miles A., "Studies of lateral dispersion in the ocean", 1998-09, DOI:10.1575/1912/8852, https://hdl.handle.net/1912/8852
     

    Related items

    Showing items related by title, author, creator and subject.

    • Thumbnail

      Understanding the ocean carbon and sulfur cycles in the context of a variable ocean : a study of anthropogenic carbon storage and dimethylsulfide production in the Atlantic Ocean 

      Levine, Naomi M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2010-02)
      Anthropogenic activity is rapidly changing the global climate through the emission of carbon dioxide. Ocean carbon and sulfur cycles have the potential to impact global climate directly and through feedback loops. Numerical ...
    • Thumbnail

      A study of ocean wave statistical properties using nonlinear, directional, phase-resolved ocean wave-field simulations 

      Henry, Legena Albertha (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2010-02)
      In the present work, we study the statistics of wavefields obtained from non-linear phase-resolved simulations. The numerical model used to generate the waves models wave-wave interactions based on the fully non-linear ...
    • Thumbnail

      Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings 

      Xu, Min (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2012-02)
      The structure of the oceanic lithosphere results from magmatic and extensional processes taking place at mid-ocean ridges (MORs). The temporal and spatial scales of the variability of these two processes control the ...
    All Items in WHOAS are protected by original copyright, with all rights reserved, unless otherwise indicated. WHOAS also supports the use of the Creative Commons licenses for original content.
    A service of the MBLWHOI Library | About WHOAS
    Contact Us | Send Feedback | Privacy Policy
    Core Trust Logo