Boundary-Layer Meteorology

, Volume 148, Issue 1, pp 93–109

Improving Stable Boundary-Layer Height Estimation Using a Stability-Dependent Critical Bulk Richardson Number

Authors

  • H. Richardson
    • Department of Marine, Earth, and Atmospheric SciencesNorth Carolina State University
    • Department of Marine, Earth, and Atmospheric SciencesNorth Carolina State University
  • A. A. M. Holtslag
    • Meteorology and Air Quality SectionWageningen University
Article

DOI: 10.1007/s10546-013-9812-3

Cite this article as:
Richardson, H., Basu, S. & Holtslag, A.A.M. Boundary-Layer Meteorol (2013) 148: 93. doi:10.1007/s10546-013-9812-3

Abstract

For many decades, attempts have been made to find the universal value of the critical bulk Richardson number (\(Ri_{Bc}\); defined over the entire stable boundary layer). By analyzing an extensive large-eddy simulation database and various published wind-tunnel data, we show that \(Ri_{Bc}\) is not a constant, rather it strongly depends on bulk atmospheric stability. A (qualitatively) similar dependency, based on the well-known resistance laws, was reported by Melgarejo and Deardorff (J Atmos Sci 31:1324–1333, 1974) about forty years ago. To the best of our knowledge, this result has largely been ignored. Based on data analysis, we find that the stability-dependent \(Ri_{Bc}\) estimates boundary-layer height more accurately than the conventional constant \(Ri_{Bc}\) approach. Furthermore, our results indicate that the common practice of setting \(Ri_{Bc}\) as a constant in numerical modelling studies implicitly constrains the bulk stability of the simulated boundary layer. The proposed stability-dependent \(Ri_{Bc}\) does not suffer from such an inappropriate constraint.

Keywords

Boundary-layer height Large-eddy simulation Low-level jet Resistance laws Stable boundary layer

Copyright information

© Springer Science+Business Media Dordrecht 2013