Predictability of Dry Convective Boundary Layers: An LES Study

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5 Citations (Scopus)

Abstract

The predictability horizon of convective boundary layers is investigated in this study. Large-eddy simulation (LES) and direct numerical simulation (DNS) techniques are employed to probe the evolution of perturbations in identical twin simulations of a growing dry convective boundary layer. Error growth typical of chaotic systems is observed, marked by two phases. The first comprises an exponential error growth as , with δ0 as the initial error, δ(t) as the error at time t, and Λ as the Lyapunov exponent. This phase is independent of the perturbation wavenumber, and the perturbation energy grows following a self-similar spectral shape dominated by higher wavenumbers. The nondimensional error growth rate in this phase shows a strong dependence on the Reynolds number (Re). The second phase involves saturation of the error. Here, the error growth follows Lorenz dynamics with a slower saturation of successively larger scales. An analysis of the spectral decorrelation times reveals two regimes: an Re-independent regime for scales larger than the boundary layer height and an Re-dependent regime for scales smaller than , which are found to decorrelate substantially faster for increasing Reynolds numbers
Original languageEnglish
Pages (from-to)2715-2727
JournalJournal of the Atmospheric Sciences
Volume73
Issue number7
DOIs
Publication statusPublished - Jun 2016

Keywords

  • Circulation/ Dynamics
  • Convection;
  • Nonlinear dynamics
  • Atm/Ocean Structure/ Phenomena;
  • Boundary layer
  • Forecasting
  • Numerical weather prediction/forecasting;
  • Models and modeling
  • Large eddy simulations
  • Numerical weather prediction/forecasting

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