Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716450
Title: Internal tides in Whittard Canyon
Author: Aslam, Tahmeena
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2017
Availability of Full Text:
Access through EThOS:
Access through Institution:
Abstract:
Submarine canyons are common bathymetric features incising the shelf edge and are known to trap and focus internal waves leading to high levels of turbulent mixing. Whittard Canyon, located at the Celtic Sea shelf edge, is a dendritic canyon where little is known about the internal tide, yet where it is postulated to have a huge impact on biology within the canyon and also play a role in the generation of nepheloid layers. High-resolution simulations of the M2 tide in Whittard Canyon using a modified version of the Princeton Ocean Model are used to determine the generation, propogation, spatial structure and dissipation of the internal tide within the canyon. Shamrock canyon and Brenot Spur are identified as key remote sources of internal tide generation, which modulate local generation in a flux-conversion feedback mechanism which causes the observed assymmetry in barotropic-tobaroclinic conversion within the canyon limbs. Depth-integrated baroclinic energy flux within the canyon is elevated, but variably so in different limbs, with values reaching >8 kW m¡1. The eastern limb of the canyon is notable for being particularly energetic. Enhancement of near-bottom baroclinic tidal currents are seen within the canyon with velocities reaching 0.4 m s¡1. The three-dimensional structure exhibits bottom intensification due to topographic focusing by the steep canyon walls, and the dominantly supercritical limb heads. Within the upper canyon the internal tide exhibits a typical mode-1 structure. Cores of baroclinic energy flux, in a dominantly up-canyon direction, form over the depth range of 1000-2500 m and are correlated with potential source regions for nepheloid layers. The sensitivity of the model to bathymetric resolution is tested and it is found that using 500 m resolution bathymetry results in domain-averaged conversion rates higher than for the smoothed bathymetries tested, highlighting the need for high-quality, high-resolution bathymetric datasets.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.716450  DOI: Not available
Share: