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Residual circulation and stratification in the Liverpool Bay region of freshwater influence

Verspecht, Florence; Rippeth, Tom P.; Simpson, John H.; Souza, Alejandro J.; Burchard, Hans; Howarth, M. John. 2009 Residual circulation and stratification in the Liverpool Bay region of freshwater influence. Ocean Dynamics, 59 (5). 765-779. 10.1007/s10236-009-0233-2

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Abstract/Summary

Wind and tidal straining are proposed as key mechanisms influencing the magnitude and timing of the horizontal flux of freshwater across regions of freshwater influence (ROFIs). Evidence for this hypothesis is presented in estimates of the tidally averaged residual current profile, obtained from 5 years of continuous acoustic doppler current profiler measurements in the Liverpool Bay ROFI. The modified horizontal Richardson number (R-x(wt)), which includes both the tidal and the wind forcing, was assessed as a measure of stratification. R-x(wt) was found to be a good indicator of the timing of the evolution and destruction of stratification, but was not as successful as an indicator of the magnitude of stratification, both enduring and periodic. The observed mean residual velocities are compared to those predicted by a classical solution, and the eddy viscosity (N-z) is shown to be a control on differences between the observed and predicted circulation. Principal component analysis is used to show that the strongest residual currents occur when the water column periodically alternates between a well-mixed and stratified state, a consequence of straining, rather than simply related to the density gradient. Evidence of wind straining was found in the correspondence between the wind direction and the near surface and near bed residual current direction.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/s10236-009-0233-2
Programmes: POL Programmes
ISSN: 1616-7341
Additional Information. Not used in RCUK Gateway to Research.: 14th International Biennial Conference on Physics of Estuaries and Coastal Seas AUG 15-29, 2008 Liverpool, ENGLAND
Additional Keywords: Residual circulation; Stratification; Tidal straining; Wind straining; ROFI; Liverpool Bay ESTUARINE STRATIFICATION; WIND; MODEL; DISSIPATION; FLOWS; CYCLE; FIELD; TIDE NISCFEB10 AJWFEB10 HIJ THEME 10 REF ISI LIVERPOOL BAY OPM2009 AR0910 OVERSEAS CO-AUTHORS (1) UK UNIVERSITY CO-AUTHORS (3)
NORA Subject Terms: Marine Sciences
Date made live: 12 May 2010 11:04
URI: http://nora.nerc.ac.uk/id/eprint/9769

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