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The subtidal behaviour of the Celtic Sea — III. A model of shelf waves and surges on a wide shelf

Huthnance, J.M.. 1986 The subtidal behaviour of the Celtic Sea — III. A model of shelf waves and surges on a wide shelf. Continental Shelf Research, 5 (3). 347-377. 10.1016/0278-4343(86)90003-8

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Abstract/Summary

We consider a wide (>100km, say) straight continental shelf meeting the ocean at a steep continental slope. Trapped barotropic waves include a fast Kelvin wave, and a first mode shelf wave in the form of a slower ‘coastal Kelvin wave’ confined to the shelf. The speeds of all other (subinertial barotropic) shelf waves tend to zero, if the shelf becomes level and the continental slope becomes vertical. Stratification effects are limited to these other modes and possibly the first mode at short wavelengths; internal Kelvin wave speeds are small compared with the ‘coastal Kelvin wave’ speed on a wide shelf. Hence the step-shelf model (e.g.Munket al., 1970, Geophysical Fluid Dynamics,6, 161–235) is a valid limit despite having only two modes; all other shelf wave modes respond only slowly to meteorological forcing and their coastal elevations tend to zero. Responses to pressure and wind forcing of various frequencies and scales over the shelf and ocean are considered. A forced combination of fast and coastal Kelvin modes (only) appears to be sufficient representation, particularly for coastal sea level. The model is compared with observed meteorologically forced sea levels, particularly at Newlyn, Cornwall (50°06'N, 5°34'W; about 300 km from the Celtic Sea shelf edge). Results are qualitatively good, dominance by low modes explaining the observed simple, large-scale form of the response. However, the analytical model over-responds, by a factor of about 2. The irregular and broken Celtic Sea coastline is expected to reduce the actual response. Although the model can explain the general preponderance of clockwise-polarised currents, it cannot match their complex spatial dependence guided by the irregular Celtic Sea geometry.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/0278-4343(86)90003-8
Programmes: POL Programmes
ISSN: 02784343
Date made live: 01 Jul 2013 16:15 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/502486

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