Scattering of the low-mode internal tide at the Line Islands Ridge
Scattering of the low-mode internal tide at the Line Islands Ridge
Date
2015-02
Authors
Haji, Maha N.
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Date Created
Location
Pacific Ocean
DOI
10.1575/1912/7208
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Keywords
Thomas G. Thompson (Ship) Cruise TN259
Kilo Moana (Ship) Cruise KM1102
Kilo Moana (Ship) Cruise KM1115
Ocean waves
Internal waves
Kilo Moana (Ship) Cruise KM1102
Kilo Moana (Ship) Cruise KM1115
Ocean waves
Internal waves
Abstract
The scattering of low-mode internal tides by ocean-floor topography is extensively
studied through analytical models and field observations at the Line Islands Ridge
(LIR). An existing Green function method is utilized to examine the generation of
internal tides by idealized topographic shapes as well as realistic transects of the LIR.
The method is also applied to examine the scattering of a mode-1 internal tide at
these topographies to determine the relative high mode energy
flux due to generated
and scattered internal tides at the realistic transects.
A method of determining the modal content of an internal wave field is advanced
to account for arbitrary stratification and rotation. It is then adjusted to allow for
image loss as is common to oceanographic studies. Its performance is compared to the
existing regression method widely used by oceanographers to determine the modal
content of internal tides. The results from this comparison are used to inform the
analysis of the field observations.
This thesis concludes by examining the modal content of the LIR as determined
from measurements taken during the 150-day EXperiment on Internal Tide Scattering
(EXITS) NSF field study. Motivated by satellite altimetry data and three-dimensional
numerical model studies, the EXITS cruise sought to observe the internal tide scattering
process in the ocean for the first time. The data from three moorings equipped
with moored profilers, spanning total depths of 3000-5000 m is analyzed to determine
the modal content of the southward propagating internal tide before and after
it encounters the ridge for evidence of topographic scattering.
Description
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2015
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Citation
Haji, M. N. (2015). Scattering of the low-mode internal tide at the Line Islands Ridge [Doctoral thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server. https://doi.org/10.1575/1912/7208