Boundary-Layer Meteorology

, Volume 147, Issue 1, pp 51–82

The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer

  • Andrey A. Grachev
  • Edgar L Andreas
  • Christopher W. Fairall
  • Peter S. Guest
  • P. Ola G. Persson
Article

DOI: 10.1007/s10546-012-9771-0

Cite this article as:
Grachev, A.A., Andreas, E.L., Fairall, C.W. et al. Boundary-Layer Meteorol (2013) 147: 51. doi:10.1007/s10546-012-9771-0

Abstract

Measurements of atmospheric turbulence made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to determine the limits of applicability of Monin–Obukhov similarity theory (in the local scaling formulation) in the stable atmospheric boundary layer. Based on the spectral analysis of wind velocity and air temperature fluctuations, it is shown that, when both the gradient Richardson number, Ri, and the flux Richardson number, Rf, exceed a ‘critical value’ of about 0.20–0.25, the inertial subrange associated with the Richardson–Kolmogorov cascade dies out and vertical turbulent fluxes become small. Some small-scale turbulence survives even in this supercritical regime, but this is non-Kolmogorov turbulence, and it decays rapidly with further increasing stability. Similarity theory is based on the turbulent fluxes in the high-frequency part of the spectra that are associated with energy-containing/flux-carrying eddies. Spectral densities in this high-frequency band diminish as the Richardson–Kolmogorov energy cascade weakens; therefore, the applicability of local Monin–Obukhov similarity theory in stable conditions is limited by the inequalities RiRicr and RfRfcr. However, it is found that Rfcr  =  0.20–0.25 is a primary threshold for applicability. Applying this prerequisite shows that the data follow classical Monin–Obukhov local z-less predictions after the irrelevant cases (turbulence without the Richardson–Kolmogorov cascade) have been filtered out.

Keywords

Flux–profile relationshipsCritical Richardson numberMonin–Obukhov similarity theoryNieuwstadt local scalingNon-Kolmogorov turbulenceRichardson–Kolmogorov cascadeSHEBAStable boundary layerz-less similarity

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Andrey A. Grachev
    • 1
  • Edgar L Andreas
    • 2
  • Christopher W. Fairall
    • 3
  • Peter S. Guest
    • 4
  • P. Ola G. Persson
    • 1
  1. 1.NOAA Earth System Research Laboratory/Cooperative Institute for Research in Environmental SciencesUniversity of ColoradoBoulderUSA
  2. 2.North West Research Associates, Inc.LebanonUSA
  3. 3.NOAA Earth System Research LaboratoryBoulderUSA
  4. 4.Naval Postgraduate SchoolMontereyUSA