Nearly three months of current meter records from five moorings off
the Oregon coast taken between October 1977 and January 1978 were analyzed
for near-inertial motions. The moorings were located from the midshelf
out to the foot of the continental slope, spanning the continental
margin. All but two of the eleven current meters were continuously
below the mixed layer. For spectral analysis, the current observation
period was divided into two time periods, one with large amplitude
near-inertial motion (41.1 cm/sec maximum of the band-passed records)
throughout and the other with much less near-inertial energy. The
spectra of the current meter records showed between a 1 and 6% increase
in frequency of the near-inertial peak above f (= 0.0592 cph) in all
but three cases. The exceptions showed spectral peaks about 14% below
f and were linked to a Doppler shift. The period of large amplitude
near-inertial motion had diagonal coherence scales of over 450 meters
vertically and 115 kilometers horizontally. An east-west (cross-shelf)
wavelength of about 50 kilometers was estimated directly from the phase
differences between current meters with roughly horizontal separations.
The observed response of a current meter about 35 meters below
the mixed layer to sharp maxima in the wind stress was similar to that predicted by the Pollard and Millard (1970) model for wind forced
near-inertial motions in the surface mixed layer. The winds associated
with a series of atmospheric fronts were apparently responsible for
generating a 14-day period of large amplitude near-inertial motion
observed below the mixed layer. / Graduation date: 1982
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27706 |
| Date | 30 April 1982 |
| Creators | Anderson, Iain |
| Contributors | Huyer, Adriana |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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