The share of the mean turbulent kinetic energy in the near-neutral surface layer for high and low wind speeds
We examine the dependence on wind speed of the share of the mean turbulent kinetic energy among the three velocity components in the near-neutral surface layer. To contrast the general behaviour and the local effects, four datasets are considered, corresponding to different surfaces and environmenta...
| Authors: | , , , , , , |
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| Format: | article |
| Publication Date: | 2019 |
| Country: | España |
| Institution: | Universidad Complutense de Madrid (UCM) |
| Repository: | Docta Complutense |
| Language: | English |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/13761 |
| Online Access: | https://hdl.handle.net/20.500.14352/13761 |
| Access Level: | Open access |
| Keyword: | 52 Stable boundary-layer Flux-profile relationships Similarity theory Standard deviations Closure-model Spectra Temperature Parameters Regimes Física atmosférica 2501 Ciencias de la Atmósfera |
| Summary: | We examine the dependence on wind speed of the share of the mean turbulent kinetic energy among the three velocity components in the near-neutral surface layer. To contrast the general behaviour and the local effects, four datasets are considered, corresponding to different surfaces and environmental conditions. For high wind speeds (i.e., wind speed ≈ 10 ms^(−1)), the shares are well-defined and about the same for all sites. As wind speed decreases (becoming ≈ 1 ms^(−1)), large record-to-record variability occurs giving, on average, an almost isotropic state for the horizontal velocity components. Through spectral analysis, we relate this behaviour to the low-frequency, submeso motions and to the lack of conditions required by Reynolds averaging. The implications for modelling are also discussed, showing that the wind speed, or a related quantity, must be accounted for, besides stability, in second-order closures. |
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