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The interaction of large amplitude internal seiches with a shallow sloping lakebed: observations of benthic turbulence in Lake Simcoe, Ontario, Canada

Citation

Cossu, R and Wells, MG, The interaction of large amplitude internal seiches with a shallow sloping lakebed: observations of benthic turbulence in Lake Simcoe, Ontario, Canada, PLoS ONE, 8, (3) Article e57444. ISSN 1932-6203 (2013) [Refereed Article]


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Copyright Statement

Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0) http://creativecommons.org/licenses/by/3.0/

DOI: doi:10.1371/journal.pone.0057444

Abstract

Observations of the interactions of large amplitude internal seiches with the sloping boundary of Lake Simcoe, Canada show a pronounced asymmetry between up- and downwelling. Data were obtained during a 42-day period in late summer with an ADCP and an array of four thermistor chains located in a 5 km line at the depths where the thermocline intersects the shallow slope of the lakebed. The thermocline is located at depths of 12-14 m during the strongly stratified period of late summer. During periods of strong westerly winds the thermocline is deflected as much as 8 m vertically and interacts directly with the lakebed at depth between 14-18 m. When the thermocline was rising at the boundary, the stratification resembles a turbulent bore that propagates up the sloping lakebed with a speed of 0.05-0.15 m s-1 and a Froude number close to unity. There were strong temperature overturns associated with the abrupt changes in temperature across the bore. Based on the size of overturns in the near bed stratification, we show that the inferred turbulent diffusivity varies by up to two orders of magnitude between up- and downwellings. When the thermocline was rising, estimates of turbulent diffusivity were high with KZ ~10-4 m2s-1, whereas during downwelling events the near-bed stratification was greatly increased and the turbulence was reduced. This asymmetry is consistent with previous field observations and underlines the importance of shear-induced convection in benthic bottom boundary layers of stratified lakes.

Item Details

Item Type:Refereed Article
Keywords:article, benthic turbulence, benthos, Canada, internal seiche, lake bed, lake ecosystem, pelagic zone, sloping boundary, summer, thermistor, thermocline, water and water related phenomena, water temperature, wind
Research Division:Engineering
Research Group:Maritime Engineering
Research Field:Marine Engineering
Objective Division:Transport
Objective Group:Water Transport
Objective Field:Water Transport not elsewhere classified
Author:Cossu, R (Dr Remo Cossu)
ID Code:94971
Year Published:2013
Web of Science® Times Cited:16
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2014-09-22
Last Modified:2014-12-08
Downloads:334 View Download Statistics

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