Predictability of Dry Convective Boundary Layers: An LES Study
| Autor: | Siddhartha Mukherjee, Harmen J. J. Jonker, Jerôme Schalkwijk |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Physics
Atmospheric Science 010504 meteorology & atmospheric sciences Meteorology Mathematical analysis Direct numerical simulation Reynolds number Perturbation (astronomy) Lyapunov exponent 01 natural sciences Convective Boundary Layer 010305 fluids & plasmas Physics::Fluid Dynamics Boundary layer symbols.namesake 0103 physical sciences symbols Wavenumber Growth rate 0105 earth and related environmental sciences |
| Zdroj: | Journal of the Atmospheric Sciences. 73:2715-2727 |
| ISSN: | 1520-0469 0022-4928 |
| DOI: | 10.1175/jas-d-15-0206.1 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|