Mean Wind Speed Measurements in Turbulence

MacCready, Paul B.

doi:10.1175/1520-0450(1966)005<0219:mwsmit>2.0.co;2

Cited by 53 publications

(14 citation statements)

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“…This overspeeding phenomenon, and the various effects contributing to it, were first reviewed comprehensively by MacCready (1966). He showed that one of the error causes, which he called 'data processing error' and which is denoted here by EQ, is independent of cup characteristics.…”

Section: Appendix Cup Anemometer Overspeeding At Bedford and At Kansasmentioning

confidence: 99%

A revaluation of the Kansas mast influence on measurements of stress and cup anemometer overspeeding

Wieringa

1980

Boundary-Layer Meteorol

179

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For the 1968 Kansas atmospheric surface-layer experiment, a supplementary analysis is made of the evaluation procedure. Available data on the ratio of wind speeds measured on separate booms show a variation with wind direction which is too large for an open mast. Actually the Kansas mast appears to have carried a bulky array of apparatus at the sonic anemometer levels. It is shown that the air flow interference caused by this obstacle can be satisfactorily estimated by way of potential flow calculations. From these it follows that the sonic anemometer measurements probably have undervalued the free-flow eddy stress by 20% to 30%, which implies that the simultaneous drag plate measurements of stress were generally correct. Also the overestimation of the mean wind speed by the Kansas cup anemometer is found to have been 6% rather than 10%. Some Kansas evaluation results are amended accordingly. The von Karma, constant is found to be 0.41 rather than 0.35, and the near-adiabatic eddy diffusivity ratio K,IK, becomes 1.0 rather than 1.3. The flux-gradient relations (Businger et al., 1971) after similar revision no longer differ significantly from those obtained elsewhere.

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Section: Appendix Cup Anemometer Overspeeding At Bedford and At Kansasmentioning

confidence: 99%

A revaluation of the Kansas mast influence on measurements of stress and cup anemometer overspeeding

Wieringa

1980

Boundary-Layer Meteorol

179

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“…3). The differences in the results could be attributed to one or a combination of the following: (a) errors associated with measuring wind speeds on the site using cuprotation anemometers, due to the response time of the rotating cups to sudden changes in wind speed and direction (MacCready, 1966;Sarre, 1989); (b) a need to have anemometers or other types of wind measurements mounted much closer to the surface, i.e., about half a meter, to ensure that the shear velocity determinations are taken only within the constant stress layer of the wind profiledunfortunately, all wind measurements were taken from fixed heights and there was no preplanned methodology to measure u * ; (c) considering hourly wind speed average may affect the threshold shear velocity during the sampling period; i.e., gusts can initiate sand movement despite the mean velocity remaining below the threshold value; (d) errors resulting from interference of the air flow caused by the trap (Horikawa and Shen, 1960;Cermak et al, 1982), and by not being perfectly aligned to the desired direction; and (e) unsteady state in the field owing to wind fluctuations in nature, in addition to that the wind profiles used in this study were not corrected for stability effects due to a thermal stratification.…”

Section: Discussionmentioning

confidence: 99%

Modeling the aeolian sand transport for the desert of Kuwait: Constraints by field observations

Al-Awadhi

Alawadhi

2009

Journal of Arid Environments

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“…Errors associated with measuring wind speeds on the site using cup-rotation anemometers, due to the response time of the rotating cups to sudden changes in wind speed and direction (MacCready 1966;Sarre 1988) or due to ignoring the bounce effects. 2.…”

Section: Discussionmentioning

confidence: 99%

Preliminary evaluation of the applicability of sand transport formulae for use in Kuwait

Al-Awadhi

Al-Sudairawi

2002

Bulletin of Engineering Geology and the Environment

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Field experiments were conducted to measure sand transport rate using eight vertical sand traps and the speed of wind-blown sand in a natural setting. A Leatherman sand trap with an inlet width of 0.01 m and a height of 1.5 m was selected to measure sand¯ux in the ®eld. The trap was assessed for its ef®ciency by comparing its collection of sand particles concurrently with the collection by a fence of 50% porosity and 2 m height, erected near the trap. It was found that such a trap design tends to under-collect material under variable winds by about 40% compared with the fence. The wind direction and speed were measured at ®ve ®xed heights: 2, 4, 6, 8 and 10 m and at 5-s intervals. Based on the available records, the wind shear velocity in eight directions was determined for the dates of collection in the sand traps. The sand transport rates were then predicted using four wellknown sand transport equations. Setting the actual coef®cients of these equations to a unity, the¯ux for each run was calculated and then compared with the calibrated¯ux derived from the trap collections.

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Mean Wind Speed Measurements in Turbulence

Cited by 53 publications

References 0 publications

A revaluation of the Kansas mast influence on measurements of stress and cup anemometer overspeeding

A revaluation of the Kansas mast influence on measurements of stress and cup anemometer overspeeding

Modeling the aeolian sand transport for the desert of Kuwait: Constraints by field observations

Preliminary evaluation of the applicability of sand transport formulae for use in Kuwait

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