Modal decomposition of tidally-forced internal waves (reconstructed from timeseries data)

• Author / Creator

  Kaminski, Alexis K.

• An algorithm is presented that disentangles the temporal and spatial structure
  of polychromatic internal wave fields generated through tidal conversion
  without a-priori knowledge of the topographic details. This spatial structure
  is relevant in estimating the location of ocean mixing. Using the (J+1) forcing
  frequencies associated with the wave field, a 2(J +1)×2(J +1) system is
  solved yielding, mode-by-mode, the frequency-specific mode strengths γjn or
  normalized mode strength ratios γjn/|γj1|, where j = 0, . . . , J. Both linear and
  nonlinear stratifications are considered.
  Synthetic data at laboratory and oceanographic length scales are used for
  verification. Excellent agreement is seen between recovered mode strengths and
  theoretical values from the synthetic data when using exact forcing frequencies.
  When forcing frequencies are determined via fast Fourier transform, the agreement
  is slightly less robust, with up to 18% error, although qualitative trends
  are still well captured. The algorithm may therefore be extended to problems
  of internal wave generation beyond tidal conversion.

• Subjects / Keywords

  • Multiple forcing frequencies
  • Varying stratification
  • Modal decomposition
  • Internal waves
  • Linear stratification

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3K653

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.