Representation of the Heated Planetary Boundary Layer in Mesoscale Models with Coarse Vertical Resolution

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  • 1 Department of Environmental Sciences, University of Virginia, Charlottesville 22903
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Abstract

This paper uses a prognostic equation suggested by Deardorff for the, growth of the planetary boundary layer to close the parameterization scheme for vertical turbulent mixing in the planetary boundary layer. The following major conclusions are obtained:

  1. The prognostic equation for the growth of the planetary boundary layer is much superior to the diagnostic form used earlier by Pielke.
  2. The growth of the planetary boundary layer into a region with substantial vertical shear of the horizontal wind markedly alters the locations of sea-breeze convergence zones.
  3. By improving the boundary layer parameterization scheme given in Pielke, the simulation of vertical turbulent mixing by eddy coefficients which are a function of distance from the ground results in predictions which are as good as those obtained with Deardorff's much more sophisticated model, and agree favorably with those observed during Day 33 of the Wangara experiment.
  4. The effect of decreasing the resolution from 31 levels to 8 levels in the boundary layer parameterization scheme does not seriously degrade the solutions, implying that the scheme discussed in this paper is a useful tool to represent the heated boundary layer in mesoscale models.

Abstract

This paper uses a prognostic equation suggested by Deardorff for the, growth of the planetary boundary layer to close the parameterization scheme for vertical turbulent mixing in the planetary boundary layer. The following major conclusions are obtained:

  1. The prognostic equation for the growth of the planetary boundary layer is much superior to the diagnostic form used earlier by Pielke.
  2. The growth of the planetary boundary layer into a region with substantial vertical shear of the horizontal wind markedly alters the locations of sea-breeze convergence zones.
  3. By improving the boundary layer parameterization scheme given in Pielke, the simulation of vertical turbulent mixing by eddy coefficients which are a function of distance from the ground results in predictions which are as good as those obtained with Deardorff's much more sophisticated model, and agree favorably with those observed during Day 33 of the Wangara experiment.
  4. The effect of decreasing the resolution from 31 levels to 8 levels in the boundary layer parameterization scheme does not seriously degrade the solutions, implying that the scheme discussed in this paper is a useful tool to represent the heated boundary layer in mesoscale models.
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