Modification of mean flow and turbulent energy by a change in surface roughness under conditions of neutral stability

Peterson, Ernest W.

doi:10.1002/qj.49709540509

Cited by 134 publications

(85 citation statements)

References 7 publications

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“…The upper level of the transition layer constitutes the top of the internal boundary layer. Floors et al (2011) found, from an analysis of measurements at Høvsøre, that the height of the internal boundary layer for momentum and wind velocity are different, in agreement with results from classical model simulations of the internal boundary layer, such as those of Rao et al (1974) and Peterson (1969). It was found that the flow at Høvsøre was in full equilibrium with the land surface below 15 m; followed by a transition layer in which the wind velocity conforms to that over the sea; the top of this layer is at ≈80 m and above this the marine wind profile prevails although the momentum is still in a transition phase between sea and land conditions.…”

Section: Reversal-height Analysissupporting

confidence: 64%

Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

Gryning

Floors

Peña

et al. 2015

Boundary-Layer Meteorol

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Wind-speed observations from tall towers are used in combination with observations up to 600 m in altitude from a Doppler wind lidar to study the long-term conditions over suburban (Hamburg), rural coastal (Høvsøre) and marine (FINO3) sites. The variability in the wind field among the sites is expressed in terms of mean wind speed and Weibull distribution shape-parameter profiles. The consequences of the carrier-to-noise-ratio (CNR) threshold-value choice on the wind-lidar observations are revealed as follows. When the wind-lidar CNR is lower than a prescribed threshold value, the observations are often filtered out as the uncertainty in the wind-speed measurements increases. For a pulsed heterodyne Doppler lidar, use of the traditional -22 dB CNR threshold value at all measuring levels up to 600 m results in a ≈7 % overestimation in the long-term mean wind speed over land, and a ≈12 % overestimation in coastal and marine environments. In addition, the height of the profile maximum of the shape parameter of the Weibull distribution (so-called reversal height) is found to depend on the applied CNR threshold; it is found to be lower at small CNR threshold values. The reversal height is greater in the suburban (high roughness) than in the rural (low roughness) area. In coastal areas the reversal height is lower than that over land and relates to the internal boundary layer that develops downwind from the coastline. Over the sea the shape parameter increases towards the sea surface. A parametrization of the vertical profile of the shape parameter fits well with observations over land, coastal regions and over the sea. An applied model for the dependence of the reversal height on the surface roughness is in good agreement with the observations over land.

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Section: Reversal-height Analysissupporting

confidence: 64%

Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

Gryning

Floors

Peña

et al. 2015

Boundary-Layer Meteorol

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“…3, Bognaes mast), that wind profiles above and below h are approximately logarithmic. More accurate theoretical models (e.g., Peterson, 1969) show, however, that this picture is only approximately correct.…”

Section: Data Basementioning

confidence: 99%

“…Therefore, Peterson et al (1979) also studied the profiles at another site, Bognaes, where the slope was negligible. We have also used some of the Bognaes results.…”

Section: Data Basementioning

confidence: 99%

“…But, because of the slope of the land, the profile above the "kink" is steeper , and below flatter than it would have been over flat terrain (see Peterson et al, 1980, andTaylor, 1978). The profiles on mast I I of the Ris* 78 experiment have similar properties as those on the tall mast, and have been discussed by Jensen and Peterson (1978), and by Peterson et al (1980). The appearance of a near-logarithmic profile for z<h, does not imply that u* is independent of height (see e.g.…”

Section: Data Basementioning

confidence: 99%

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Some Wind Characteristics over Complex Terrain

Panofsky

Leyi

1982

Journal of the Meteorological Society of Japan

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Airflow characteristics in neutral conditions over two kinds of complex terrain are compared: on hill tops, and over land, downstream of water. In spite of the large differences in the dynamical characteristics, several similarities emerge: logarithmic wind profiles with large shear near the surface, in spite of vertically decreasing stress; weaker wind shears above, and agreement between surface stresses inferred from wind profiles with Reynolds stresses extrapolated downward. Also, in both cases, dissipation is locally balanced by mechanical energy production.

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“…When one roughness regime gives way to another, the flow near the ground gradually adjusts to the new surface characteristics. This process is often represented mathematically by local internal boundary layers (IBLs), which grow vertically downstream of a roughness boundary (Elliott 1958;Panofsky and Townsend 1964;Townsend 1965;Peterson 1969;Blom and Wartena 1969).…”

Section: Introductionmentioning

confidence: 99%

Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

Vanderwende

Lundquist

2015

Boundary-Layer Meteorol

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The collocation of cropland and wind turbines in the US Midwest region introduces complex meteorological interactions that could influence both agriculture and wind-power production. Crop management practices may affect the wind resource through alterations of land-surface properties. We use the weather research and forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. A hypothetical wind farm consisting of 121 1.8-MW turbines is represented using the WRF model wind-farm parametrization. We represent the impact of selecting soybeans rather than maize by altering the aerodynamic roughness length in a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 0.1 and 0.25 m represent the mature soy crop and a mature maize crop, respectively. In all but the most stable atmospheric conditions, statistically significant hub-height wind-speed increases and rotor-layer wind-shear reductions result from switching from maize to soybeans. Based on simulations for the entire month of August 2013, wind-farm energy output increases by 14 %, which would yield a significant monetary gain. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop-management practices. These considerations must be balanced by other influences on crop choice such as soil requirements and commodity prices.

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Modification of mean flow and turbulent energy by a change in surface roughness under conditions of neutral stability

Cited by 134 publications

References 7 publications

Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

Some Wind Characteristics over Complex Terrain

Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

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