Geostrophic Drag Law in Conventionally Neutral Atmospheric Boundary Layer: Simplified Parametrization and Numerical Validation

Luoqin Liu*, Xiyun Lu, Richard J.A.M. Stevens

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

This study investigates the parameterization of the geostrophic drag law (GDL) for conventionally neutral atmospheric boundary layers (CNBLs). Utilizing large eddy simulations, we confirm that in CNBLs capped by a potential temperature inversion, the boundary-layer height scales as u∗/Nf, where u∗ represents the friction velocity, N the free-atmosphere Brunt–Väisälä frequency, and f the Coriolis parameter. Additionally, we confirm that the wind gradients normalized by the Brunt–Väisälä frequency have universal profiles above the surface layer. Leveraging these physical insights, we derived analytical expressions for the GDL coefficients A and B, correcting the earlier form of Zilitinkevich and Esau (Q J R Meteorol Soc 131:1863–1892, 2005). These expressions for A and B have been validated numerically, ensuring their accuracy in representing the geostrophic drag coefficient u∗/G (G is the geostrophic wind speed) and the cross-isobaric angle. This work extends the range for which the GDL has been validated up to u∗/G=[0.019,0.047]. This further supports the application of GDL to CNBLs over a broader range of u∗/G, which is useful for meteorological applications such as wind energy.

Original languageEnglish
Article number37
JournalBoundary-Layer Meteorology
Volume190
Issue number8
DOIs
Publication statusPublished - 10 Aug 2024

Keywords

  • 2024 OA procedure
  • Conventionally neutral
  • Geostrophic drag law
  • Large eddy simulations
  • Atmospheric boundary layer

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