Predictability of Dry Convective Boundary Layers

An LES Study

Journal article (2016)

Authors

S. Mukherjee ChemE/Transport Phenomena - AS , Atmospheric Remote Sensing - CEG
J. Schalkwijk Atmospheric Physics
H.J.J. Jonker Atmospheric Physics
Research Group
Atmospheric Remote Sensing (CEG) (TU Delft)
Forecasting Boundary layer Nonlinear dynamics Circulation/ Dynamics Large eddy simulations Numerical weather prediction/forecasting Convection; Atm/Ocean Structure/ Phenomena; Numerical weather prediction/forecasting; Models and modeling
More Info
expand_more

Published Date

2016-6

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Civil Engineering & Geosciences

Department

Geoscience and Remote Sensing

Research Group

Atmospheric Remote Sensing

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