Ocean Dynamics

, Volume 52, Issue 4, pp 153–168 | Cite as

Modelling of convective turbulence with a two-equation k-ɛ turbulence closure scheme

  • Adolf Stips
  • Hans Burchard
  • Karsten Bolding
  • Walter Eifler

Abstract

 In this study we aim at comparing turbulence parameters from field observations and model simulations under convective conditions. The comparison is focused on the depth dependence and temporal dynamics of viscous and diffusive dissipation rates ɛ and χ. The near-surface observations were obtained by using a quasi-free-rising profiler which measured small-scale shear and temperature fluctuations to within the vicinity of the water surface. Convective conditions during the experiment are characterized by low wind speeds (between 0 and 4 m s−1) and a typical heat loss of about 150 Wm−2. We applied a state-of-the-art two-equation k-ɛ turbulence model with an algebraic second-moment closure scheme. The qualitative agreement of the turbulence quantities resulting from observations and simulations is rather good. The temporal dynamics of the temperature field is simulated correctly, whereas in the spatial dynamics some deficiencies of the model due to its local character can be seen. It is concluded that such models realistically reproduce convective turbulence and therefore represent a reasonable compromise between complexity and simplicity, so that they can be used with acceptable costs in large-scale models.

Keywords Turbulence Numerical modelling Convective processes Dissipation rates 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Adolf Stips
    • 1
  • Hans Burchard
    • 2
  • Karsten Bolding
    • 1
  • Walter Eifler
    • 1
  1. 1.CEC Joint Research Centre, Inland and Marine Waters Unit, 21020 Ispra(VA), Italy e-mail: adolf.stips@jrc.itIT
  2. 2.Institute for Baltic Sea Research, Universität Rostock, Seestrasse 15, 18119 Rostock, GermanyDE

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