Note on the Aerodynamic Roughness Length for Complex Terrain

Thompson, Roger S.

doi:10.1175/1520-0450(1978)017<1402:notarl>2.0.co;2

Cited by 25 publications

(15 citation statements)

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“…One study, reported by Nappo (1977), was conducted in Eastern Tennessee. Thompson (1978) analyzed rawinsonde data from the Clinch River valley in Carbo, Virginia, while Noilhan et al (1982) conducted a radiosonde experiment in southern France, about 30 km north of the Pyrenees. In the fist two of these studies, the wind profile was simply assumed to be logarithmic, to determine the roughness height.…”

Section: Experimental Studies Over Complexterrainmentioning

confidence: 96%

“…Smith and Carson (1977) applied (5) with c, = 0.4, and by defining & as twice the ratio of the average height between peaks and valleys and the average distance between these peaks. Thompson (1978) calculated the density ,$ for several parallel lines drawn in the direction of the wind on a topographic map; the number of contours was counted on the windward slopes on all the lines and this was multiplied by the contour interval and then divided by the total length of all the lines. In what follows, the symbols & and 1 are used interchangeably.…”

Section: Roughness Parameters Estimated From Surface Featuresmentioning

confidence: 99%

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Wind profile constants in a neutral atmospheric boundary layer over complex terrain

Kustas

Brutsaert

1986

Boundary-Layer Meteorol

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The roughness height zc and the zero-plane displacement height d,, were determined for a region of complex terrain in the Pre-Alps of Switzerland. This region is characterized by hills of the order of 100 m above the valley elevations, and by distances between ridges of the order of 1 km; it lies about 20 to 30 km north from the Alps. The experimental data were obtained from radiosonde observations under near neutral conditions. The analysis was based on the assumption of a logarithmic profile for the mean horizontal wind existing over one half of the boundary layer. The resulting (z,/h) and (d,,/h) (where h is the mean height of the obstacles) were found to be in reasonable agreement with available relationships in terms of placement density and shape factor of the obstacles, which were obtained in previous experiments with h-scales 2 to 4 orders of magnitude smaller than the present ones.

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Section: Experimental Studies Over Complexterrainmentioning

confidence: 96%

Section: Roughness Parameters Estimated From Surface Featuresmentioning

confidence: 99%

Wind profile constants in a neutral atmospheric boundary layer over complex terrain

Kustas

Brutsaert

1986

Boundary-Layer Meteorol

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“…The density function has constant values on these ellipses. So the ellipses generated out of (13) are referred to as ellipses of equal probability. The percentile ellipses can be generated based on value variations as…”

Section: Bivariate Normal Distribution (Bnd) Wind Modelmentioning

confidence: 99%

“…The relation of 0 to various terrain types is extensively studied by Nappo [9], Smedman-Hogstrom and Hogstrom [10], Hicks et al [11], Kondo and Yamazawa [12], Thompson [13], and Garratt [14] and occurrence of imaginary and small 0 values was reported by Panofsky and Peterson [15] over a narrow peninsula surrounded by bays of varying width. The 0 values may vary with the heights of wind measurements as profiles from tower will sense only local terrain irregularities of small horizontal size and also at the low level the roughness length is representative of the locally smooth surface crops [16,17].…”

Section: Introductionmentioning

confidence: 99%

Coastal Boundary Layer Characteristics of Wind, Turbulence, and Surface Roughness Parameter over the Thumba Equatorial Rocket Launching Station, India

Namboodiri

Krishnan

Nileshwar

et al. 2014

Journal of Climatology

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The study discusses the features of wind, turbulence, and surface roughness parameter over the coastal boundary layer of the Peninsular Indian Station, Thumba Equatorial Rocket Launching Station (TERLS). Every 5 min measurements from an ultrasonic anemometer at 3.3 m agl from May 2007 to December 2012 are used for this work. Symmetries in mesoscale turbulence, stress off-wind angle computations, structure of scalar wind, resultant wind direction, momentum flux ( ), Obukhov length ( ), frictional velocity ( * ), w-component, turbulent heat flux ( ), drag coefficient ( ), turbulent intensities, standard deviation of wind directions ( ), wind steadiness factor-relationship, bivariate normal distribution (BND) wind model, surface roughness parameter ( 0 ), 0 and wind direction ( ) relationship, and variation of 0 with the Indian South West monsoon activity are discussed.

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“…On the other hand, under calm conditions, the profile functions, q~ and *'H, become large and are not well-known. For these reasons, in past field experiments, roughness parameters over hilly complex terrain have been determined with assumptions related to ~0 and do (Thompson, 1978;Kustas and Brutsaert, 1986;Grant and Mason, 1990).…”

Section: Introductionmentioning

confidence: 99%

An analytical method for the determination of the roughness parameters over complex regions

Mikami¹,

Toya²,

Yasuda

1996

Boundary-Layer Meteorol

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The values of roughness length for momentum za and zero-plane displacement da over a hilly rough complex region with vegetation were evaluated without any assumption concerning to and de. It was found that for widely scattered profile data, the method of least squares will not give a reasonable result in determining the roughness parameters. For this purpose, the method of maximum correlation was introduced instead. This method gave a fair result for captive balloon observations conducted in hilly terrain mainly covered with forest in the northwestern part of the Kanto Plain, Japan.

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Note on the Aerodynamic Roughness Length for Complex Terrain

Cited by 25 publications

References 0 publications

Wind profile constants in a neutral atmospheric boundary layer over complex terrain

Wind profile constants in a neutral atmospheric boundary layer over complex terrain

Coastal Boundary Layer Characteristics of Wind, Turbulence, and Surface Roughness Parameter over the Thumba Equatorial Rocket Launching Station, India

An analytical method for the determination of the roughness parameters over complex regions

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