Infragravity waves over topography : generation, dissipation, and reflection
Thomson, James M.
MetadataShow full item record
LocationSouthern California coast
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.
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
Showing items related by title, author, creator and subject.
Petillo, Stephanie M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)The capabilities of autonomous underwater vehicles (AUVs) and their ability to perform tasks both autonomously and adaptively are rapidly improving, and the desire to quickly and efficiently sample the ocean environment ...
Frame, Caitlin H. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2011-06)Atmospheric nitrous oxide N2O concentrations have been rising steadily for the past century as a result of human activities. In particular, human perturbation of the nitrogen cycle has increased the N2O production rates ...
French, Katherine L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)Tracing the evolution of Earth’s redox history is one of the great challenges of geobiology and geochemistry. The accumulation of photosynthetically derived oxygen transformed the redox state of Earth’s surface environments, ...