Publication Date:
2022-05-25
Description:
Submitted to the Joint Program in Physical Oceanography 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 2006
Description:
Ocean surface infragravity waves (periods from 20 to 200 s) observed along the southern
California coast are shown to be sensitive to the bottom topography of the shelf
region, where propagation is linear, and of the nearshore region, where nonlinearity
is important. Infragravity waves exchange energy with swell and wind waves (periods
from 5 to 20 s) via conservative nonlinear interactions that approach resonance with
decreasing water depth. Consistent with previous results, it is shown here that as
waves shoal into water less than a few meters deep, energy is transfered from swell
to infragravity waves. In addition, it is shown here that the apparent dissipation of
infragravity energy observed in the surfzone is the result of nonlinear energy transfers
from infragravity waves back to swell and wind waves. The energy transfers are
sensitive to the shallow water bottom topography. On nonplanar beach profiles the
transfers, and thus the amount of infragravity energy available for reflection from the shoreline, change with the tide, resulting in the tidal modulation of infragravity energy observed in bottom-pressure records on the continental shelf. The observed wave propagation over the shelf topography is dominated by refraction, and the observed partial reflection from, and transmission across, a steep-walled submarine canyon is consistent with long-wave theory. A generalized regional model incorporating these results predicts the observed infragravity wave amplitudes over variable bottom topography.
Description:
Support from the Office of Naval Research (Coastal Geosciences Program, N00014-02-10145), the National Science Foundation (Physical Oceanography, OCE-0115850),
Keywords:
Waves
;
Ocean bottom
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
3634207 bytes
Format:
application/pdf
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