Diapycnal Mixing in the Thermocline of Lakes : Estimations by Different Methods

A. Etemad-Shahidi, Jorg Imberger

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    In order to evaluate the performance of different methods for estimation of the vertical eddy diffusivity in thermally stratified lakes, two field studies were conducted in Lake Biwa, Japan and Lake Kinneret, Israel. Lake Biwa experienced three typhoons during the campaign while Lake Kinneret experienced high winds in the afternoons. Microstructure profiles were collected by a portable flux profiler (PFP) during calm and disturbed periods. Then, the vertical eddy diffusivity was estimated by three indirect methods. The estimated vertical eddy diffusivities varied more than one order of magnitude, from 4.7 x 10(-7) to 7.7 x 10(-6) m(2) s(-1). The comparison of results with previous buoyancy flux measurements and scaling arguments showed that the Dillon-Park's method is not appropriate and Osborn - Cox method performs better than Osborn method in the studied case. Furthermore, the low value of vertical eddy diffusivity within the thermocline suggests that within the thermocline of these lakes, diffusive vertical transport can be neglected.
    Original languageEnglish
    Pages (from-to)227 - 240
    JournalEnvironmental Fluid Mechanics
    Volume6
    Issue number3
    DOIs
    Publication statusPublished - 2006

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    thermocline
    Lakes
    Temperature distribution
    diffusivity
    eddy
    lake
    Fluxes
    profiler
    flux measurement
    Buoyancy
    buoyancy
    method
    microstructure
    Microstructure

    Cite this

    Etemad-Shahidi, A. ; Imberger, Jorg. / Diapycnal Mixing in the Thermocline of Lakes : Estimations by Different Methods. In: Environmental Fluid Mechanics. 2006 ; Vol. 6, No. 3. pp. 227 - 240.
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    abstract = "In order to evaluate the performance of different methods for estimation of the vertical eddy diffusivity in thermally stratified lakes, two field studies were conducted in Lake Biwa, Japan and Lake Kinneret, Israel. Lake Biwa experienced three typhoons during the campaign while Lake Kinneret experienced high winds in the afternoons. Microstructure profiles were collected by a portable flux profiler (PFP) during calm and disturbed periods. Then, the vertical eddy diffusivity was estimated by three indirect methods. The estimated vertical eddy diffusivities varied more than one order of magnitude, from 4.7 x 10(-7) to 7.7 x 10(-6) m(2) s(-1). The comparison of results with previous buoyancy flux measurements and scaling arguments showed that the Dillon-Park's method is not appropriate and Osborn - Cox method performs better than Osborn method in the studied case. Furthermore, the low value of vertical eddy diffusivity within the thermocline suggests that within the thermocline of these lakes, diffusive vertical transport can be neglected.",
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    Diapycnal Mixing in the Thermocline of Lakes : Estimations by Different Methods. / Etemad-Shahidi, A.; Imberger, Jorg.

    In: Environmental Fluid Mechanics, Vol. 6, No. 3, 2006, p. 227 - 240.

    Research output: Contribution to journalArticle

    TY - JOUR

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    AU - Etemad-Shahidi, A.

    AU - Imberger, Jorg

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    N2 - In order to evaluate the performance of different methods for estimation of the vertical eddy diffusivity in thermally stratified lakes, two field studies were conducted in Lake Biwa, Japan and Lake Kinneret, Israel. Lake Biwa experienced three typhoons during the campaign while Lake Kinneret experienced high winds in the afternoons. Microstructure profiles were collected by a portable flux profiler (PFP) during calm and disturbed periods. Then, the vertical eddy diffusivity was estimated by three indirect methods. The estimated vertical eddy diffusivities varied more than one order of magnitude, from 4.7 x 10(-7) to 7.7 x 10(-6) m(2) s(-1). The comparison of results with previous buoyancy flux measurements and scaling arguments showed that the Dillon-Park's method is not appropriate and Osborn - Cox method performs better than Osborn method in the studied case. Furthermore, the low value of vertical eddy diffusivity within the thermocline suggests that within the thermocline of these lakes, diffusive vertical transport can be neglected.

    AB - In order to evaluate the performance of different methods for estimation of the vertical eddy diffusivity in thermally stratified lakes, two field studies were conducted in Lake Biwa, Japan and Lake Kinneret, Israel. Lake Biwa experienced three typhoons during the campaign while Lake Kinneret experienced high winds in the afternoons. Microstructure profiles were collected by a portable flux profiler (PFP) during calm and disturbed periods. Then, the vertical eddy diffusivity was estimated by three indirect methods. The estimated vertical eddy diffusivities varied more than one order of magnitude, from 4.7 x 10(-7) to 7.7 x 10(-6) m(2) s(-1). The comparison of results with previous buoyancy flux measurements and scaling arguments showed that the Dillon-Park's method is not appropriate and Osborn - Cox method performs better than Osborn method in the studied case. Furthermore, the low value of vertical eddy diffusivity within the thermocline suggests that within the thermocline of these lakes, diffusive vertical transport can be neglected.

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