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 language | English |
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Pages (from-to) | 2715-2727 |
Journal | Journal of the Atmospheric Sciences |
Volume | 73 |
Issue number | 7 |
DOIs | |
Publication status | Published - 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