Bathymetric Influence on the Coastal Sea Level Response to Ocean Gyres at Western Boundaries

Wise, Anthony, Hughes, Chris W ORCID: 0000-0002-9355-0233 and Polton, Jeff A ORCID: 0000-0003-0131-5250 (2018) Bathymetric Influence on the Coastal Sea Level Response to Ocean Gyres at Western Boundaries. JOURNAL OF PHYSICAL OCEANOGRAPHY, 48 (12). pp. 2949-2964.

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Abstract

<jats:title>Abstract</jats:title><jats:p>It is our aim with this paper to investigate how the presence of a continental shelf and slope alters the relationship between interior ocean dynamics and western boundary (coastal) sea level. The assumption of a flat-bottomed basin with vertical sidewall at the coast is shown to hide the role that depth plays in the net force acting on the coast. A linear <jats:italic>β</jats:italic>-plane theory is then developed describing the transmission of sea level over variable depth bathymetry as analogous to the steady advection–diffusion of a thermal fluid. The parameter <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf1.gif" /></jats:inline-formula>, relating the friction parameter <jats:italic>r</jats:italic> to the bathymetry depth <jats:italic>H</jats:italic> and width <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf2.gif" /></jats:inline-formula>, is found to determine the contribution of interior sea level to coastal sea level, with small <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf3.gif" /></jats:inline-formula> giving maximum penetration and large <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf4.gif" /></jats:inline-formula> maximum insulation. In the small <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf5.gif" /></jats:inline-formula> (infinite friction) limit the frictional boundary layer extends far offshore, and coastal sea level tends toward the vertical sidewall solution. Adding simple stratification produces exactly the same result but with reduced effective depth and hence enhanced penetration. Penetration can be further enhanced by permitting weakly nonlinear variations of thermocline depth. Wider and shallower shelves relative to the overall scales are also shown to maximize penetration for realistic values of <jats:inline-formula><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpo-d-18-0007.1-inf6.gif" /></jats:inline-formula>. The theory implies that resolution of bathymetry and representation of friction can have a large impact on simulated coastal sea level, calling into question the ability of coarse-resolution models to accurately represent processes determining the dynamic coastal sea level.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	Coastal flows, Topographic effects, Gyres, Sea level
Depositing User:	Symplectic Admin
Date Deposited:	19 Dec 2018 12:50
Last Modified:	19 Jan 2023 01:08
DOI:	10.1175/JPO-D-18-0007.1
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3030259