Analytical Reduced Models for the Non-stationary Diabatic Atmospheric Boundary Layer

Mostafa Momen, Elie R. Bou-Zeid

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Geophysical boundary-layer flows feature complex dynamics that often evolve with time; however, most current knowledge centres on the steady-state problem. In these atmospheric and oceanic boundary layers, the pressure gradient, buoyancy, Coriolis, and frictional forces interact to determine the statistical moments of the flow. The resulting equations for the non-stationary mean variables, even when succinctly closed, remain challenging to handle mathematically. Here, we derive a simpler physical model that reduces these governing unsteady Reynolds-averaged Navier–Stokes partial differential equations into a single first-order ordinary differential equation with non-constant coefficients. The reduced model is straightforward to solve under arbitrary forcing, even when the statistical moments are non-stationary and the viscosity varies in time and space. The model is successfully validated against large-eddy simulation for, (1) time-variable pressure gradients, and (2) linearly time-variable buoyancy. The new model is shown to have a superior performance compared to the classic Blackadar solutions (and later improvements on these solutions), and it covers a much wider range of conditions.

Original languageEnglish (US)
Pages (from-to)383-399
Number of pages17
JournalBoundary-Layer Meteorology
Volume164
Issue number3
DOIs
StatePublished - Sep 1 2017

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Keywords

  • Large-eddy simulation
  • Low-level jet
  • Non-stationary turbulence
  • Unsteady atmospheric boundary layer
  • Variable static stability

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