Abstract
Monterey Submarine Canyon is a large, sinuous canyon off the coast of California, the upper reaches of which were the subject of an internal tide observational program using moored profilers and upward-looking moored ADCPs. The mooring observations measured a near-surface stratification change in the upper canyon, likely caused by a seasonal shift in the prevailing wind that favoured coastal upwelling. This change in near-surface stratification caused a transition in the behaviour of the internal tide in the upper canyon from a partly standing wave during pre-upwelling conditions to a progressive wave during upwelling conditions. Using a numerical model, we present evidence that either a partly standing or a progressive internal tide can be simulated in the canyon, simply by changing the initial stratification conditions in accordance with the observations. The mechanism driving the transition is a dependence of down-canyon (supercritical) internal tide reflection from the canyon floor and walls on the depth of maximum stratification. During pre-upwelling conditions, the main pycnocline extends down to 200 m (below the canyon rim) resulting in increased supercritical reflection of the up-canyon propagating internal tide back down the canyon. The large up-canyon and smaller down-canyon progressive waves are the two components of the partly standing wave. During upwelling conditions, the pycnocline shallows to the upper 50 m of the watercolumn (above the canyon rim) resulting in decreased supercritical reflection and allowing the up-canyon progressive wave to dominate.
Original language | English |
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Pages (from-to) | 164-173 |
Number of pages | 10 |
Journal | Deep-Sea Research Part II: Topical Studies in Oceanography |
Volume | 104 |
Early online date | 6 Jun 2013 |
DOIs | |
Publication status | Published - 2014 |
Keywords
- Internal waves
- Internal tides
- Submarine canyons
- USA
- California
- Monterey Bay
Profiles
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Rob Hall
- School of Environmental Sciences - Associate Professor
- Centre for Ocean and Atmospheric Sciences - Member
- Collaborative Centre for Sustainable Use of the Seas - Member
Person: Research Group Member, Academic, Teaching & Research