Wind-Tunnel Study Of Atmospheric Stable Boundary Layers Over A Rough Surface

Ohya, Yuji

doi:10.1023/a:1018767829067

Cited by 139 publications

(124 citation statements)

References 39 publications

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“…According to Ohya (2001), Grachev et al (2007b), Esau and Grachev (2007), Zilitinkevich et al (2007) and Anderson (2009), the Prandtl number increases with Ri in supercritical conditions. However, the detailed analysis of Grachev et al (2007b) implies that such a result is spurious.…”

Section: Discussionmentioning

confidence: 96%

Gradient‐based scales and similarity laws in the stable boundary layer

Sorbjan

2010

Quart J Royal Meteoro Soc

105

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Three gradient-based scaling systems for the stably stratified boundary layer are introduced and examined by using data collected during the SHEBA field programme in the Arctic. The resulting similarity functions for fluxes and variances are expressed in an analytical form, which is expected to be essentially unaffected by self-correlation in a very stable regime. The flux Richardson number Rf is found to be proportional to the Richardson number Ri, with the proportionality coefficient varying slightly with stability, from 1.11 to 1.47. The Prandtl number decreases from 0.9 in nearly neutral conditions to 0.7 for larger values of Ri. The negative correlation coefficient between the vertical velocity and temperature, −r wθ , has a local maximum at Ri of about 0.08, and monotonically decreases with larger values of the Richardson number. The turbulent kinetic energy budget indicates that for Ri > 0.7, turbulence must be non-stationary, i.e. decaying or sporadic. Turbulence within the stably stratified boundary layer can be classified by four regimes: 'nearly neutral' (0 < Ri < 0.02), 'weakly stable' (0.02 < Ri < 0.12), 'very stable' (0.12 < Ri < 0.7), and 'extremely stable' (Ri > 0.7).

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Section: Discussionmentioning

confidence: 96%

Gradient‐based scales and similarity laws in the stable boundary layer

Sorbjan

2010

Quart J Royal Meteoro Soc

105

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“…It is, however, reported to increase with increasing gradient Richardson number in the statically stable regime (Kondo et al 1978;Ueda et al 1981;Kim and Mahrt 1992;Ohya 2001;Grachev et al 2007a, b). This relationship is mostly verified on flux towers near the surface, for example the Surface Heat Budget of the Arctic (SHEBA) Ocean experiment with measurements under 20 m in height (Grachev et al 2007a, b) or the 213-m flux tower covering the lower portion of the boundary layer used by Ueda et al (1981).…”

Section: Pr T = U W ∂θ V ∂Z θ V W ∂U ∂Zmentioning

confidence: 99%

“…Various phenomena are suggested to cause countergradient transport of momentum and heat under statically stable conditions. Examples include wavy motions, breaking of waves due to Kelvin-Helmholtz instability (Ohya 2001) and the formation of longitudinal vortical structures that are elongated in the streamwise direction (Iida and Nagano 2007).…”

Section: Downgradient and Countergradient Transportmentioning

confidence: 99%

“…Turbulent eddies in the atmosphere usually satisfy the Taylor hypothesis (Willis and Deardorff 1976), so that they may be considered frozen as they travel past a sensor (Taylor 1938) under all stability conditions (Geernaert et al 1987;Ohya 2001). Given that aircraft speeds are usually about one order of magnitude higher than typical wind speeds, it is a good practical assumption to consider equivalence between flux tower (stationary probe) and aircraft (moving probe) turbulence measurements for atmospheric studies.…”

Section: Stationary Versus Moving Probe Measurementsmentioning

confidence: 99%

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Characterization and Parametrization of Reynolds Stress and Turbulent Heat Flux in the Stably-Stratified Lower Arctic Troposphere Using Aircraft Measurements

Aliabadi

Staebler

Liu

et al. 2016

Boundary-Layer Meteorol

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Aircraft measurements are used to characterize properties of clear-air turbulence in the lower Arctic troposphere. For typical vertical resolutions in general circulation models, there is evidence for both downgradient and countergradient vertical turbulent transport of momentum and heat in the mostly statically stable conditions within both the boundary layer and the free troposphere. Countergradient transport is enhanced in the free troposphere compared to the boundary layer. Three parametrizations are suggested to formulate the turbulent heat flux and are evaluated using the observations. The parametrization that accounts for the anisotropic nature of turbulence and buoyancy flux predicts both observed downgradient and countergradient transport of heat more accurately than those that do not. The inverse turbulent Prandtl number is found to only weakly decrease with increasing gradient Richardson number in a statistically significant way, but with large scatter in the data. The suggested parametrizations can potentially improve the performance of regional and global atmospheric models.

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“…7c, namely a decrease with increasing z followed by a rise, which they attributed as here to the rise in the mean temperature. For further relevant discussion see also Ohya (2001) andNieuwstadt (1984). …”

Section: Stable Boundary Layermentioning

confidence: 99%

Wind-Tunnel Simulation of the Wake of a Large Wind Turbine in a Stable Boundary Layer. Part 1: The Boundary-Layer Simulation

Hancock

Pascheke

2013

Boundary-Layer Meteorol

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Abstract:Measurements have been made in both a neutral and a stable boundary layer as part of an investigation of the wakes of wind turbines in an offshore environment, in the EnFlo stratified flow wind tunnel. The working section is long enough for the flow to have become very nearly invariant with streamwise distance. In order to be systematic, the flow profile generators of Irwintype spires and surface roughness were the same for both neutral and stable conditions. Achieving the required profiles by adjusting the flow generators, even for neutral flow, is a highly iterative art, and the present results indicate that it will be no less iterative for a stable flow (as well as there being more conditions to meet), so this was not attempted in the present investigation. The stablecase flow conformed in most respects to Monin-Obukhov similarity in the surface layer. A linear temperature profile was applied at the working section inlet, resulting in a near-linear profile in the developed flow above the boundary layer and 'strong' imposed stability, while the condition at the surface was 'weak'. Aerodynamic roughness length (mean velocity) was not affected by stability even though the roughness Reynolds number < 1, while the thermal roughness length was much smaller, as is to be expected. The neutral case was Reynolds-number independent, and by inference, the stable case was also Reynolds-number independent.

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Wind-Tunnel Study Of Atmospheric Stable Boundary Layers Over A Rough Surface

Cited by 139 publications

References 39 publications

Gradient‐based scales and similarity laws in the stable boundary layer

Gradient‐based scales and similarity laws in the stable boundary layer

Characterization and Parametrization of Reynolds Stress and Turbulent Heat Flux in the Stably-Stratified Lower Arctic Troposphere Using Aircraft Measurements

Wind-Tunnel Simulation of the Wake of a Large Wind Turbine in a Stable Boundary Layer. Part 1: The Boundary-Layer Simulation

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