Effect of water depth and the bottom boundary layer upon internal wave generation over abrupt topography

Xing, Jiuxing; Davies, Alan M.. 2010 Effect of water depth and the bottom boundary layer upon internal wave generation over abrupt topography. Ocean Dynamics, 60 (3). 597-616. 10.1007/s10236-010-0280-8

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Abstract/Summary

The role of water depth and bottom boundary layer turbulence upon lee-wave generation in sill regions is examined. Their effect upon vertical mixing is also considered. Calculations are performed using a non-hydrostatic model in cross-section form with a specified tidal forcing. Initial calculations in deeper water and a sill height such that the sill top is well removed from the surrounding bed region showed that downstream lee-wave generation and associated mixing increased as bottom friction coefficient k increased. This was associated with an increase in current shear across the sill. However, for a given k, increasing vertical eddy viscosity A (v) reduced vertical shear in the across sill velocity, leading to a reduction in lee-wave amplitude and associated mixing. Subsequent calculations using shallower water showed that for a given k and A (v,) lee-wave generation was reduced due to the shallower water depth and changes in the bottom boundary layer. However, in this case (unlike in the deepwater case), there is an appreciable bottom current. This gives rise to bottom mixing which in shallow water extends to mid-depth and enhances the mid-water mixing that is found on the lee side of the sill. Final calculations with deeper water but small sill height showed that lee waves could propagate over the sill, thereby reducing their contribution to mixing. In this case, bottom mixing was the major source of mixing which was mainly confined to the near bed region, with little mid-water mixing

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1007/s10236-010-0280-8
Programmes:	Oceans 2025 > Shelf and coastal processes
ISSN:	1616-7341
Additional Information. Not used in RCUK Gateway to Research.:	The original publication is available at www.springerlink.com
Additional Keywords:	INTERNAL WAVES; BOTTOM BOUNDARY LAYER; TOPOGRAPHY; CORRUGATED CONTINENTAL SLOPE; OCEAN CIRCULATION; PORTUGUESE SHELF; STRATIFIED FLOW; SOLITARY WAVES; KNIGHT INLET; SILL REGIONS; TIDAL FLOW; MODEL TIDES; MODELLING
NORA Subject Terms:	Marine Sciences
Date made live:	14 Apr 2011 16:44 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/13972

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