Correlated Vertical Wind Speeds in a Spruce Canopy

The main objective of this paper is to develop a predictive model of vertical wind speed profile. Response surface methodology (RSM) is used for this purpose. RSM is a set of statistical and mathematical techniques useful for the development, improvement and optimisation of processes. It is mainly used in industrial processes and is successfully applied in this paper to model the wind speed at the hub height of the wind turbine. An unconventional model is adopted due to the nature of the input parameters which cannot be controlled or modified. The model validation indicators, namely correlation coefficient ([Formula: see text]) and root mean square error (RMSE = 1.02), give excellent results when comparing predicted and measured wind speeds. For the same data, the RSM model gives a better RMSE compared to the conventional power law and the artificial neural network.

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Generation of the lower-thermospheric vertical wind estimated with the EISCAT KST radar at high latitudes during periods of moderate geomagnetic disturbance

Annales Geophysicae ◽

10.5194/angeo-26-1491-2008 ◽

2008 ◽

Vol 26 (6) ◽

pp. 1491-1505 ◽

Cited By ~ 13

Author(s):

S. Oyama ◽

B. J. Watkins ◽

S. Maeda ◽

H. Shinagawa ◽

S. Nozawa ◽

...

Keyword(s):

Wind Speed ◽

Lower Thermosphere ◽

Geomagnetic Disturbance ◽

Vertical Wind ◽

Neutral Wind ◽

High Latitudes ◽

Ionospheric Heating ◽

Wind Speeds ◽

Heating Event ◽

Order Of Magnitude

Abstract. Lower-thermospheric winds at high latitudes during moderately-disturbed geomagnetic conditions were studied using data obtained with the European Incoherent Scatter (EISCAT) Kiruna-Sodankylä-Tromsø (KST) ultrahigh frequency (UHF) radar system on 9–10 September 2004. The antenna-beam configuration was newly designed to minimize the estimated measurement error of the vertical neutral-wind speed in the lower thermosphere. This method was also available to estimate the meridional and zonal components. The vertical neutral-wind speed at 109 km, 114 km, and 120 km heights showed large upward motions in excess of 30 m s−1 in association with an ionospheric heating event. Large downward speeds in excess of −30 m s−1 were also observed before and after the heating event. The meridional neutral-wind speed suddenly changed its direction from equatorward to poleward when the heating event began, and then returned equatorward coinciding with a decrease in the heating event. The magnetometer data from northern Scandinavia suggested that the center of the heated region was located about 80 km equatorward of Tromsø. The pressure gradient caused the lower-thermospheric wind to accelerate obliquely upward over Tromsø in the poleward direction. Acceleration of the neutral wind flowing on a vertically tilted isobar produced vertical wind speeds larger by more than two orders of magnitude than previously predicted, but still an order of magnitude smaller than observed speeds.

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Estimating wind power generation capacity in Zimbabwe using vertical wind profile extrapolation techniques: A case study

Journal of Energy in Southern Africa ◽

10.17159/2413-3051/2021/v32i1a8205 ◽

2021 ◽

Vol 32 (1) ◽

pp. 14-26

Author(s):

L. Gunda ◽

E. Chikuni ◽

H. Tazvinga ◽

J. Mudare

Keyword(s):

Wind Power ◽

Electricity Generation ◽

Wind Profile ◽

Test Site ◽

Vertical Wind ◽

Weather Data ◽

Analysis Tool ◽

Extrapolation Methods ◽

Wind Speeds ◽

Generation Capacity

Only 40% of Zimbabwe’s population has access to electricity. The greater proportion of the power is generated from thermal stations, with some from hydro and solar energy sources. However, there is little investment in the use of wind for electricity generation except for small installations in the Eastern Highlands, as Zimbabwe generally has wind speeds which are too low to be utilised for electricity generation. This paper presents the use of vertical wind profile extrapolation methods to determine the potential of generating electricity from wind at different hub heights in Zimbabwe, using the Hellman and exponential laws to estimate wind speeds. The estimated wind speeds are used to determine the potential of generating electricity from wind. Mangwe district in Matabeleland South province of Zimbabwe was used as a test site. Online weather datasets were used to estimate the wind speeds. The investigation shows that a 2.5kW wind turbine installation in Mangwe can generate more than 3MWh of energy per annum at hub heights above 40m, which is enough to supply power to a typical Zimbabwean rural village. This result will encourage investment in the use of wind to generate electricity in Zimbabwe. Highlights Wind power utilisation is low in Zimbabwe. Vertical wind profile is estimated using extrapolation methods. Online weather data for soil and water analysis tool was used. Electricity can viably be generated from wind in Zimbabwe.

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Do High-Speed Winds Aloft Influence the Occurrence of Hail?

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-42.7.443 ◽

1961 ◽

Vol 42 (7) ◽

pp. 443-446 ◽

Cited By ~ 3

Author(s):

B. Ratner

Keyword(s):

United States ◽

High Speed ◽

The United States ◽

Vertical Wind ◽

Wind Data ◽

Jet Stream ◽

Southern France ◽

Wind Speeds

In an article contained in Geophysical Monograph No. 5, H. Dessens concludes, as the result of experiments conducted in southern France, that the presence of a jet stream at upper levels is the factor which transforms a thunderstorm into a destructive hail storm and that large shears in vertical-wind speeds are conducive to formation of hail. The writer, by climatological analysis of hail and upper-air wind data for the contiguous United States, shows that Dessens' theories do not apply to conditions in the United States.

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Improved Wind and Turbulence Measurements Using a Low-Cost 3-D Sonic Anemometer at a Low-Wind Site

The Open Atmospheric Science Journal ◽

10.2174/1874282300802010131 ◽

2008 ◽

Vol 2 (1) ◽

pp. 131-138 ◽

Cited By ~ 1

Author(s):

Brent M. Bowen

Keyword(s):

Standard Deviation ◽

Wind Direction ◽

Sonic Anemometer ◽

Vertical Wind ◽

Wind Speeds ◽

Low Wind Speeds ◽

Mechanical Sensors ◽

Wind Vane ◽

Cup Anemometer ◽

Propeller Anemometer

A year of data from sonic anemometer and mechanical wind sensors was analyzed and compared at a low-wind site. Results indicate that 15-minute average and peak 1-second wind speeds (u) from the sonic agree well with data derived from a co-located cup anemometer over a wide range of speeds. Wind direction data derived from the sonic also agree closely with those from a wind vane except for very low wind speeds. Values of standard deviation of longitudinal wind speed (σu) and wind direction fluctuations (σø) from the sonic and mechanical sensors agree well for times with u > 2 ms-1 but show significant differences with lower u values. The most significant differences are associated with the standard deviation of vertical wind fluctuations (σw): the co-located vertical propeller anemometer yields values increasingly less than those measured by the sonic anemometer as u decreases from 2.5 approaching 0 ms-1. The combination of u over-estimation and under-estimation of σw from the mechanical sensors at low wind speeds causes considerable underestimation of the standard deviation of vertical wind angle fluctuations (σø), an indicator of vertical dispersion. Calculations of σø from sonic anemometer measurements are typically 5° to 10° greater than from the mechanical sensors when the mechanical instruments indicate that σø < 5° or so. The errors with the propeller anemometer, cup anemometer and wind vane, caused by their inability to respond to higher frequency (smaller scale) turbulent fluctuations, can therefore lead to large (factors of 2 to 10 or more) errors in both the vertical and horizontal dispersion during stable conditions with light winds. The sonic anemometer clearly provides more accurate and reliable wind data than the mechanical wind sensor with u < 2.5 ms-1

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An Experimental Investigation of Streamwise and Vertical Wind Fields on a Typical Three-Dimensional Hill

Applied Sciences ◽

10.3390/app10041463 ◽

2020 ◽

Vol 10 (4) ◽

pp. 1463

Author(s):

Guohui Shen ◽

Jianfeng Yao ◽

Wenjuan Lou ◽

Yong Chen ◽

Yong Guo ◽

...

Keyword(s):

Wind Speed ◽

Three Dimensional ◽

Vertical Wind ◽

Streamwise Direction ◽

Wind Fields ◽

Wind Speeds ◽

Upstream Side ◽

Speed Up ◽

The Mean ◽

The Hill

To study the streamwise and vertical wind fields on a typical three-dimensional hill, wind tunnel tests were performed. The mean values and turbulence intensities of the streamwise and vertical wind speeds of the typical positions above the hill were measured, and they are presented in the form of contour maps for design. Furthermore, the speed-up of the mean wind speeds in the streamwise direction was compared with codes. Finally, the windage yaw of a jumper cable was examined as an example of how to take into account the streamwise and vertical wind field influence on the wind load in the analysis of wind-induced responses. The results show that the most significant speed-up effect in the streamwise direction occurs on the hill crest, and the wind speed-up decreases with the increase of the height. Overall, the wind speed-up along the crosswind center line is larger than that along the along-wind center line of the hill. In the codes, the speed-up effect specified for the structure at half the height of the upstream side of the hill is relatively conservative. With regard to the mean wind speed in the vertical direction, the wind climbing effect located at half the height of the upstream side of the hill is the most significant. The area with the stronger turbulence intensity appears at the foot of the upstream and downstream sides of the hill. The influence of the vertical wind on the jumper cable is remarkable where the wind climbing effect is the most significant, which is worthy of attention in the design of the structure immersed in a hilly terrain-disturbed wind field.

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Role of variability in determining the vertical wind speeds and structure

Journal of Geophysical Research Atmospheres ◽

10.1029/2011ja016714 ◽

2011 ◽

Vol 116 (A12) ◽

pp. n/a-n/a ◽

Cited By ~ 9

Author(s):

Erdal Yiğit ◽

Aaron J. Ridley

Keyword(s):

Vertical Wind ◽

Wind Speeds

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EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.22-24.051-058 ◽

2018 ◽

pp. 51-58

Author(s):

B. P. Khozyainov

Keyword(s):

Wind Turbine ◽

Flow Velocity ◽

Wind Power ◽

Wind Turbines ◽

Power Efficiency ◽

Air Flow ◽

Geometrical Parameters ◽

Wind Speeds ◽

Analytical Studies ◽

Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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