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Turbulence and stratification in Priest Pot, a productive pond in a sheltered environment.

Folkard, Andrew M and Sherborne, Amy J and Coates, Michael J (2007) Turbulence and stratification in Priest Pot, a productive pond in a sheltered environment. Limnology, 8 (2). pp. 113-120. ISSN 1439-8621

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    Abstract

    Priest Pot is an example of the abundant ponds which, collectively, contribute crucially to species diversity. Despite extensive biological study, little has been reported about the physical framework which supports its ecological richness. This paper elucidates the physical character of Priest Pot�s water column and thus that of similar waterbodies. Vertical thermal microstructure profiles were recorded during summer 2003, and analysed alongside concurrent meteorological data. During summer stratification, the thermal structure appeared to be dominated by surface heat fluxes. Surface wind stress, limited by sheltering vegetation, caused turbulent overturns once a surface mixed layer was present, but appeared to contribute little to setting up the thermal structure. Variations in full-depth mean stratification occurred pre-dominantly over seasonal and ~5-day time scales, the passage of atmospheric pressure systems being posited as the cause of the latter. In the uppermost ~0.5 m, where the stratification varied at sub-daily time scales, turbulence was active (sensu Ivey and Imberger, 1991) when this layer was mixed, with dissipation values � ~ 10-8 m2s-3 and vertical diffusivity KZ = 10-4-10-6 m2s-1. Where the water column was stratified, turbulence was strongly damped by both buoyancy and viscosity and KZ was an order of magnitude smaller. Vertical transport in the mixed layer occurred via many small overturns (Thorpe scale rms and maximum values typically 0.02m and 0.10m respectively) and seston were fully mixed through the water column.

    Item Type: Article
    Journal or Publication Title: Limnology
    Additional Information: The original publication is available at www.springerlink.com
    Uncontrolled Keywords: lakes and ponds ; stratification ; turbulent mixing ; solar radiation ; wind forcing
    Subjects: G Geography. Anthropology. Recreation > G Geography (General)
    Departments: Faculty of Science and Technology > Lancaster Environment Centre
    ID Code: 479
    Deposited By: Dr. Andrew Folkard
    Deposited On: 22 Mar 2007
    Refereed?: Yes
    Published?: Published
    Last Modified: 26 Jul 2012 18:12
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/479

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