Wind Velocity Vertical Extrapolation by Extended Power Law

Wind energy gains more attention day by day as one of the clean renewable energy resources. We predicted wind speed vertical extrapolation by using extended power law. In this study, an extended vertical wind velocity extrapolation formulation is derived on the basis of perturbation theory by considering power law and Weibull wind speed probability distribution function. In the proposed methodology not only the mean values of the wind speeds at different elevations but also their standard deviations and the cross-correlation coefficient between different elevations are taken into consideration. The application of the presented methodology is performed for wind speed measurements at Karaburun/Istanbul, Turkey. At this location, hourly wind speed measurements are available for three different heights above the earth surface.

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Anemometry

Meteorological Measurement Systems ◽

10.1093/oso/9780195134513.003.0009 ◽

2001 ◽

Author(s):

Fred V. Brock ◽

Scott J. Richardson

Keyword(s):

Wind Speed ◽

Wind Velocity ◽

Elevation Angle ◽

Vertical Component ◽

Wind Vector ◽

Wind Speeds ◽

North East ◽

Orthogonal Components ◽

The Mean ◽

Design Type

The function of an anemometer (sometimes with a wind vane) is to measure some or all components of the wind velocity vector. It is common to express the wind as a two-dimensional horizontal vector since the vertical component of the wind speed is usually small near the earth’s surface. In some cases, the vertical component is important and then we think of the wind vector as being three-dimensional. The vector can be written as orthogonal components (u, v, and sometimes w] where each component is the wind speed component blowing in the North, East, or vertically up direction. Alternatively, the vector can be written as a speed and a direction. In the horizontal case, the wind direction is the direction from which the wind is blowing measured in degrees clockwise from North. The wind vector can be expressed in three dimensions as the speed, direction in the horizontal plane as above, and the elevation angle. Standard units for wind speed (a scalar component of the velocity) are m s-1 and knots (nautical miles per hour). Some conversion factors are shown in table 7-1. Wind velocity is turbulent; that is, it is subject to variations in speed, direction, and period. The wind vector can be described in terms of mean flow and gustiness or variation about the mean. The WMO standard defines the mean as the average over 10 minutes. The ideal wind-measuring instrument would respond to the slightest breeze yet be rugged enough to withstand hurricane-force winds, respond to rapidly changing turbulent fluctuations, have a linear output, and exhibit simple dynamic performance characteristics. It is difficult to build sensors that will continue to respond to wind speeds as they approach zero or will survive as wind speeds become very large. Thus a variety of wind sensor designs and, even within a design type, a spectrum of implementations have evolved to meet our needs.

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Calibration of the depth invariant algorithm to monitor the tidal action of Rabigh City at the Red Sea Coast, Saudi Arabia

Open Geosciences ◽

10.1515/geo-2020-0217 ◽

2020 ◽

Vol 12 (1) ◽

pp. 1666-1678

Author(s):

Mohammed H. Aljahdali ◽

Mohamed Elhag

Keyword(s):

Remote Sensing ◽

Saudi Arabia ◽

Wind Speed ◽

Red Sea ◽

Remote Sensing Data ◽

Microwave Remote Sensing ◽

Optical Data ◽

Mean Values ◽

Sensing Data ◽

The Mean

AbstractRabigh is a thriving coastal city located at the eastern bank of the Red Sea, Saudi Arabia. The city has suffered from shoreline destruction because of the invasive tidal action powered principally by the wind speed and direction over shallow waters. This study was carried out to calibrate the water column depth in the vicinity of Rabigh. Optical and microwave remote sensing data from the European Space Agency were collected over 2 years (2017–2018) along with the analog daily monitoring of tidal data collected from the marine station of Rabigh. Depth invariant index (DII) was implemented utilizing the optical data, while the Wind Field Estimation algorithm was implemented utilizing the microwave data. The findings of the current research emphasis on the oscillation behavior of the depth invariant mean values and the mean astronomical tides resulted in R2 of 0.75 and 0.79, respectively. Robust linear regression was established between the astronomical tide and the mean values of the normalized DII (R2 = 0.81). The findings also indicated that January had the strongest wind speed solidly correlated with the depth invariant values (R2 = 0.92). Therefore, decision-makers can depend on remote sensing data as an efficient tool to monitor natural phenomena and also to regulate human activities in fragile ecosystems.

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The Characteristics of West Season Wind and Wave as well as Their Impacts on Ferry Cruise in The Kalianget-Kangean Cruise Route, Madura, Indonesia

Pertanika Journal of Science and Technology ◽

10.47836/pjst.29.3.16 ◽

2021 ◽

Vol 29 (3) ◽

Author(s):

Viv Djanat Prasita ◽

Lukman Aulia Zati ◽

Supriyatno Widagdo

Keyword(s):

Wind Speed ◽

Wave Height ◽

The West ◽

Wind Speeds ◽

Wave Patterns ◽

Time Stamps ◽

The Mean ◽

Two Peaks ◽

The Impact ◽

Descriptive Statistical Analysis

The wind and wave conditions in the waters of the Kalianget-Kangean cruise route in the west season are relatively high so that these winds and waves can have a dangerous impact on that cruise route. The aim of this research was to analyze the characteristics of wind speed and wave height over a 10 year period (2008-2017), as well as to evaluate the weekly patterns for three months (December 2017-February 2018). These time stamps represent the west season in waters at Kalianget-Kangean route, and to identify the impact of winds and wave on this path. The method used in this research is descriptive statistical analysis to obtain the mean and maximum values of wind speed and wave height. Wind and wave patterns were analyzed by WRPlot and continued with mapping of wind and wave patterns in the waters of Kalianget-Kangean and its surroundings. The data used was obtained from the Meteorology, Climatology and Geophysics Agency. The results show wind and wave characteristics with two peaks formed regularly between 2008-2017, marking the west and east monsoons. In addition, the wind speed and wave height were generally below the danger threshold, ie <10 knots and <2 m, respectively. However, there are exceptions in the west season, especially at the peak in January, where the forces are strengthened with a steady blowing direction. The maximum wind speed reaches and wave height reaches 29 knots and 6.7 m, respectively. The weekly conditions for both parameters from December 2017 to February 2018 were relatively safe, for sailing. Moreover, January 23-29, 2018 featured extreme conditions estimated as dangerous for cruise due to the respective maximum values of 25 knots and 3.8 m recorded. The channel is comparably safe, except during the western season time in December, January, February, characterized by wind speeds and wave height exceeding 21 knots and 2.5 m, correspondingly.

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Galactic cosmic-ray modulation effect by solar-wind streams

Canadian Journal of Physics ◽

10.1139/p95-094 ◽

1995 ◽

Vol 73 (9-10) ◽

pp. 642-646 ◽

Cited By ~ 3

Author(s):

M. A. El-Borie

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Cosmic Rays ◽

Solar Wind Speed ◽

Cosmic Ray ◽

Diurnal Variations ◽

Solar Cycles ◽

Mean Values ◽

Wind Speeds ◽

Cosmic Ray Modulation

Data, from the worldwide network of neutron monitors, recorded at Deep River, Hermanus, Rome, Tokyo, and Huancayo, over two solar cycles (Nos. 20 and 21) are analyzed to study the long-term variations of the solar diurnal variations as they relate to solar-wind speed. The median primary rigidities of response (Rm) for these detectors cover the range 16 GV ≤ Rm ≤ 33 GV. We discuss the solar diurnal variations (amplitude and phase) of cosmic rays as a function of solar activity. The behavior of solar diurnal phases is completely different for the two epochs of high-wind speed. Data of solar-wind speed from 1966–1986 are classified according to the state of the daily mean values. Variation in the amplitudes of the diurnal variations, as functions of the median primary rigidity of cosmic rays, for the two selected periods (1973–1975 and 1979–1981) of high and low solar-wind speeds were determined at the selected stations. The rigidity dependence of the averaged solar diurnal variations of cosmic rays related to the high solar-wind speed was studied. The most sensitive rigidity of modulation is around 20 and 30 GV during the 1973–1975 and 1979–1981 periods, respectively. Our results also show that there is a significant correlation in the solar diurnal amplitudes between the two divisions of high and low solar-wind speed days.

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On the wind resource in Algeria: Probability distributions evaluation

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650920975883 ◽

2020 ◽

pp. 095765092097588

Author(s):

Houdayfa Ounis ◽

Nawel Aries

Keyword(s):

Wind Speed ◽

Probability Distribution ◽

Probability Distributions ◽

Resource Assessment ◽

Descriptive Statistics ◽

The Other ◽

Wind Speeds ◽

Wind Resource Assessment ◽

The Mean ◽

Wind Resource

The present study aims to present a contribution to the wind resource assessment in Algeria using ERA-Interim reanalysis. Firstly, the ERA-Interim reanalysis 10 m wind speed data are considered for the elaboration of the mean annual 10 m wind speed map for a period starting from 01-01-2000 to 31-12-2017. Moreover, the present study intends to highlight the importance of the descriptive statistics other than the mean in wind resource assessment. On the other hand, this study aims also to select the proper probability distribution for the wind resource assessment in Algeria. Therefore, nine probability distributions were considered, namely: Weibull, Gamma, Inverse Gaussian, Log Normal, Gumbel, Generalized Extreme Value (GEV), Nakagami, Generalized Logistic and Pearson III. Furthermore, in combination with the distribution, three parameter estimation methods were considered, namely, Method of Moment, Maximum Likelihood Method and L-Moment Method. The study showed that Algeria has several wind behaviours due to the diversified topographic, geographic and climatic properties. Moreover, the annual mean 10 m wind speed map showed that the wind speed varies from 2.3 to 5.3 m/s, where 73% of the wind speeds are above 3 m/s. The map also showed that the Algerian Sahara is windiest region, while, the northern fringe envelopes the lowest wind speeds. In addition, it has been shown that the study of the mean wind speeds for the evaluation of the wind potential alone is not enough, and other descriptive statistics must be considered. On the other hand, among the nine considered distribution, it appears that the GEV is the most appropriate probability distribution. Whereas, the Weibull distribution showed its performance only in regions with high wind speeds, which, implies that this probability distribution should not be generalized in the study of the wind speed in Algeria.

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Evaluation of the Ocean Surface Wind Speed Change following the Super Typhoon from Space-Borne GNSS-Reflectometry

Remote Sensing ◽

10.3390/rs12122034 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2034 ◽

Cited By ~ 2

Author(s):

Hongsu Liu ◽

Shuanggen Jin ◽

Qingyun Yan

Keyword(s):

Wind Speed ◽

Correlation Coefficient ◽

Surface Wind ◽

Ocean Surface ◽

Surface Wind Speed ◽

Wind Speeds ◽

Mean Error ◽

Super Typhoon ◽

The Mean ◽

Ocean Surface Wind

Ocean surface wind speed is an essential parameter for typhoon monitoring and forecasting. However, traditional satellite and buoy observations are difficult to monitor the typhoon due to high cost and low temporal-spatial resolution. With the development of spaceborne GNSS-R technology, the cyclone global navigation satellite system (CYGNSS) with eight satellites in low-earth orbit provides an opportunity to measure the ocean surface wind speed of typhoons. Though observations are made at the extremely efficient spatial and temporal resolution, its accuracy and reliability are unclear in an actual super typhoon case. In this study, the wind speed variations over the life cycle of the 2018 Typhoon Mangkhut from CYGNSS observations were evaluated and compared with European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis-5 (ERA-5). The results show that the overall root-mean-square error (RMSE) of CYGNSS versus ECMWF was 4.12 m/s, the mean error was 1.36 m/s, and the correlation coefficient was 0.96. For wind speeds lower and greater than 15 m/s, the RMSE of CYGNSS versus ECMWF were 1.02 and 4.36 m/s, the mean errors were 0.05 and 1.61 m/s, the correlation coefficients were 0.91 and 0.90, and the average relative errors were 9.8% and 11.6%, respectively. When the typhoon reached a strong typhoon or super typhoon, the RMSE of CYGNSS with respect to ERA-5 from ECMWF was 5.07 m/s; the mean error was 3.57 m/s; the correlation coefficient was 0.52 and the average relative error was 11.0%. The CYGNSS estimation had higher precision for wind speeds below 15 m/s, but degraded when the wind speed was above 15 m/s.

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Evacuee Perception of Geophysical Hazards for Hurricane Irma

Weather Climate and Society ◽

10.1175/wcas-d-18-0019.1 ◽

2019 ◽

Vol 11 (1) ◽

pp. 217-227 ◽

Cited By ~ 5

Author(s):

Jason Senkbeil ◽

Jennifer Collins ◽

Jacob Reed

Keyword(s):

Wind Speed ◽

Storm Surge ◽

Wind Speeds ◽

Wind Gusts ◽

Different Types ◽

High Concern ◽

Rest Areas ◽

The Mean ◽

Atlantic Hurricanes ◽

Hurricane Irma

Abstract Hurricane Irma was one of the strongest Atlantic hurricanes in history before landfall and caused a large evacuation. A total of 155 evacuees at interstate rest areas were asked to rank their concern about damage at their residence for six different geophysical hurricane hazards. Additionally, they were asked about their perceived maximum wind speeds (PMWS) and the wind speeds at which they thought damage would occur (DW) at their residence. These wind speeds were then compared to the actual peak wind gusts (APG) nearest to each resident’s location. Results show a significantly greater concern for wind and storm size, compared to other hazards (tornadoes, rainfall/flooding, storm surge, falling trees). The mean PMWS of evacuees was greater than the mean APG, suggesting widespread misperception of wind speeds. Furthermore, the mean APG was less than the mean DW, and the mean PMWS was also higher than the DW. Additional tests found no significant differences in wind perception between residents with previous storm experiences and no experience, and no significant differences between those who resided in mandatory evacuation zip codes and those who did not. These results suggest that wind speed risk is poorly understood, even though it is a high concern for evacuees from hurricanes. The communication of wind speed risk in forecasts should possibly be modified by placing greater emphasis on postlandfall impacts, wind speed decay after landfall, and wind speeds that cause damage to different types of residences.

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Quantification of NOX Emissions Based on Car MAX-DOAS Measurements over Beijing and Impacts of Wind Field

10.5194/egusphere-egu2020-12459 ◽

2020 ◽

Author(s):

Xinghong Cheng

Keyword(s):

Spatial Distribution ◽

Wind Speed ◽

Wind Field ◽

Meteorological Condition ◽

Emission Rates ◽

Wind Fields ◽

Vertical Column ◽

Wind Speeds ◽

South Central ◽

The Mean

We carried out 14 days of Car MAX-DOAS experiments on the 6th Ring Rd of Beijing in January, September and October, 2014. The tropospheric vertical column densities (VCD) of NO2 are retrieved and used to estimate the emissions of NOx. The offline LAPS-WRF-CMAQ model system is used to simulate wind fields by assimilation of observational data and calculate the NO2 to NOx concentration ratios. The NOX emissions in Beijing for different seasons derived from Car MAX-DOAS measurements are compared with the multi-resolution emission inventory in China for 2012 (MEIC 2012), and impacts of wind field on estimated emissions and its uncertainties are also investigated. Results show that the NO2 VCD is higher in January than other two months and it is typically larger at the southern parts of the 6th Ring Road than the northern parts of it. Wind field has obvious impacts on the spatial distribution of NO2 VCD, and the mean NO2 VCD with south wind at most sampling points along the 6th Ring Rd is higher than north wind. The journey-to-journey variation pattern of estimated NOX emissions rates (ENOX) is consistent with that of the NO2 VCD, and ENOX is mainly determined by the NO2 VCD. In addition, the journey-to-journey ENOX in the same month is different and it is affected by wind speed, the ratio of NO2 and NOx concentration and the decay rate of NOX from the emission sources to measured positions under different meteorological condition. The ENOX ranges between 6.46&#215;1025 and 50.05&#215;1025 molec s-1. The averaged ENOX during every journey in January, September and October are respectively 35.87&#215;1025, 20.34&#215;1025, 8.96&#215;1025 molec s-1. The estimated ENOX after removing the simulated error of wind speed and observed deviation of NO2 VCD are found to be mostly closer to the MEIC 2012, but sometimes ENOX is lower or higher and it indicates that the MEIC 2012 might be overestimate or underestimate the true emissions. The estimated ENOX on January 27 and September 19 are obviously higher than other journeys in the same month because the mean NO2 VCD and Leighton ratio during these two periods are larger, and corresponding wind speeds are smaller. Additionally, because south wind may affect the spatial distribution of mean NO2 VCD in Beijing which is downwind of south-central&#160;regions of Hebei province with high source emission rates, the uncertainty of the estimated ENOX with south wind will be increased.

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Height Extrapolation of Wind Data

Journal of Solar Energy Engineering ◽

10.1115/1.3267645 ◽

1985 ◽

Vol 107 (1) ◽

pp. 10-14 ◽

Cited By ~ 17

Author(s):

A. S. Mikhail

Keyword(s):

Wind Speed ◽

Power Law ◽

Wind Data ◽

Power Law Model ◽

Short Term ◽

Shape Factors ◽

Wind Speeds ◽

Average Wind ◽

Modified Power Law

Various models that are used for height extrapolation of short and long-term averaged wind speeds are discussed. Hourly averaged data from three tall meteorological towers (the NOAA Erie Tower in Colorado, the Battelle Goodnoe Hills Tower in Washington, and the WKY-TV Tower in Oklahoma), together with data from 17 candidate sites (selected for possible installation of large WECS), were used to analyze the variability of short-term average wind shear with atmospheric and surface parameters and the variability of the long-term Weibull distribution parameter with height. The exponents of a power-law model, fit to the wind speed profiles at the three meteorological towers, showed the same variability with anemometer level wind speed, stability, and surface roughness as the similarity law model. Of the four models representing short-term wind data extrapolation with height (1/7 power law, logarithmic law, power law, and modified power law), the modified power law gives the minimum rms for all candidate sites for short-term average wind speeds and the mean cube of the speed. The modified power-law model was also able to predict the upper-level scale factor for the WKY-TV and Goodnoe Hills Tower data with greater accuracy. All models were not successful in extrapolation of the Weibull shape factors.

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Wind tunnel tests on the characteristics of wind fields over a simplified gorge

Advances in Structural Engineering ◽

10.1177/1369433216680635 ◽

2016 ◽

Vol 20 (10) ◽

pp. 1599-1611 ◽

Cited By ~ 1

Author(s):

Peng Hu ◽

Yongle Li ◽

Yan Han ◽

CS Cai ◽

Guoji Xu

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Wind Direction ◽

Wind Field ◽

Small Range ◽

Wind Fields ◽

Wind Speeds ◽

Mean Wind Speed ◽

Wind Characteristics ◽

The Mean

Characteristics of wind fields over the gorge or valley terrains are becoming more and more important to the structural wind engineering. However, the studies on this topic are very limited. To obtain the fundamental characteristics information about the wind fields over a typical gorge terrain, a V-shaped simplified gorge, which was abstracted from some real deep-cutting gorges where long-span bridges usually straddle, was introduced in the present wind tunnel studies. Then, the wind characteristics including the mean wind speed, turbulence intensity, integral length scale, and the wind power spectrum over the simplified gorge were studied in a simulated atmospheric boundary layer. Furthermore, the effects of the oncoming wind field type and oncoming wind direction on these wind characteristics were also investigated. The results show that compared with the oncoming wind, the wind speeds at the gorge center become larger, but the turbulence intensities and the longitudinal integral length scales become smaller. Generally, the wind fields over the gorge terrain can be approximately divided into two layers, that is, the gorge inner layer and the gorge outer layer. The different oncoming wind field types have remarkable effects on the mean wind speed ratios near the ground. When the angle between the oncoming wind and the axis of the gorge is in a certain small range, such as smaller than 10°, the wind fields are very close to those associated with the wind direction of 0°. However, when the angle is in a larger range, such as larger than 20°, the wind fields in the gorge will significantly change. The research conclusions can provide some references for civil engineering practices regarding the characteristics of wind fields over the real gorge terrains.

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