scholarly journals Data Clustering Reveals Climate Impacts on Local Wind Phenomena

2012 ◽  
Vol 51 (8) ◽  
pp. 1547-1557 ◽  
Author(s):  
Andrew Clifton ◽  
Julie K. Lundquist
Keyword(s):  
Wind Speed ◽  
Pressure Gradient ◽  
Climate Impacts ◽  
Climate Indices ◽  
Local Conditions ◽  
Climate Oscillations ◽  
The North ◽  
Westerly Flow ◽  
Mean Wind Speed ◽  
The Mean

AbstractThe authors demonstrate the utility of k-means clustering for identifying relationships between winds at turbine heights and climate oscillations, thereby developing a method suited for predicting the impacts of climate change on wind resources. Fourteen years of data from an 80-m tower at the National Wind Technology Center (NWTC) in Colorado have been reduced to four dominant flow phenomena using k-means clustering. At this location, this method identifies two clusters of westerly inflow (strong and weak), another cluster of flow from the north, and one of flow from the south. Similar clusters are found for the data at all heights on the tower, and each follow distinct seasonal cycles. Time series of each cluster, as well as the mean wind speed at the NWTC, are retained for comparison with climate oscillations along with the local 500-hPa pressure gradient. The mean wind speed in the surface layer is strongly correlated with the local north–south pressure gradient. The frequency of strong westerly flow is also negatively correlated with the Niño-3.4 index, whereas weaker westerly winds are negatively correlated with the Pacific–North American pattern (PNA) and Arctic Oscillation (AO). Northerly winds at the NWTC did not strongly correlate with any of the investigated climate indices (AO, PNA, and Niño-3.4). These northerly winds occur more frequently in the summer months, suggesting that these winds are more influenced by local conditions than by mesoscale forcing. This method of identifying clusters in wind data allows objective identification of wind phenomena that may benefit the deployment of wind turbines, for example, in choosing combinations of wind speed and direction to investigate for turbine siting.

scholarly journals Atmospheric Circulation Effects on Wind Speed Variability at Turbine Height

2007 ◽  
Vol 46 (4) ◽  
pp. 445-456 ◽  
Author(s):  
Katherine Klink
Keyword(s):  
Wind Speed ◽  
Pressure Gradient ◽  
Large Scale ◽  
Ground Level ◽  
The Arctic ◽  
Circulation Index ◽  
Regression Equations ◽  
Change Models ◽  
Wind Speeds ◽  
The North

Abstract Mean monthly wind speed at 70 m above ground level is investigated for 11 sites in Minnesota for the period 1995–2003. Wind speeds at these sites show significant spatial and temporal coherence, with prolonged periods of above- and below-normal values that can persist for as long as 12 months. Monthly variation in wind speed primarily is determined by the north–south pressure gradient, which captures between 22% and 47% of the variability (depending on the site). Regression on wind speed residuals (pressure gradient effects removed) shows that an additional 6%–15% of the variation can be related to the Arctic Oscillation (AO) and Niño-3.4 sea surface temperature (SST) anomalies. Wind speeds showed little correspondence with variation in the Pacific–North American (PNA) circulation index. The effect of the strong El Niño of 1997/98 on the wind speed time series was investigated by recomputing the regression equations with this period excluded. The north–south pressure gradient remains the primary determinant of mean monthly 70-m wind speeds, but with 1997/98 removed the influence of the AO increases at nearly all stations while the importance of the Niño-3.4 SSTs generally decreases. Relationships with the PNA remain small. These results suggest that long-term patterns of low-frequency wind speed (and thus wind power) variability can be estimated using large-scale circulation features as represented by large-scale climatic datasets and by climate-change models.

Scale and Lag Effects on Control of Aerodynamic Power and Loads on a HAWT Rotor

2001 ◽  
Vol 123 (4) ◽  
pp. 339-345 ◽  
Author(s):  
P. J. Moriarty ◽  
A. J. Eggers, ◽  
K. Chaney ◽  
W. E. Holley
Keyword(s):  
Control System ◽  
Fatigue Life ◽  
Wind Speed ◽  
Open Loop ◽  
Time Lags ◽  
Large Power ◽  
Lag Effects ◽  
Mean Wind Speed ◽  
The Mean ◽  
High Control

The effects of rotor scale and control system lag were examined for a variable-speed wind turbine. The scale study was performed on a teetered rotor with radii ranging between 22.5m and 33.75m. A 50% increase in radius more than doubled the rated power and annual energy capture. Using blade pitch to actively control fluctuating flatwise moments allowed for significant reductions in blade mass for a fixed fatigue life. A blade operated in closed-loop mode with a 33.75m radius weighed less than an open-loop blade with a 22.5m radius while maintaining the same fatigue life of 5×109 rotations. Actuator lag reduced the effectiveness of the control system. However, 50% reductions in blade mass were possible even when implementing a relatively slow actuator with a 1 sec. time constant. Other practical limits on blade mass may include fatigue from start/stop cycles, non-uniform turbulence, tower wake effects, and wind shear. The more aggressive control systems were found to have high control accelerations near 60 deg/s2, which may be excessive for realistic actuators. Two time lags were introduced into the control system when mean wind speed was estimated in a rapidly changing wind environment. The first lag was the length of time needed to determine mean wind speed, and therefore the mean control settings. The second was the frequency at which these mean control settings were changed. Preliminary results indicate that quickly changing the mean settings (every 10 seconds) and using a moderate length mean averaging time (60 seconds) resulted in the longest fatigue life. It was discovered that large power fluctuations occurred during open-loop operation which could cause sizeable damage to a realistic turbine generator. These fluctuations are reduced by one half or more when aerodynamic loads are actively controlled.

scholarly journals Wind speed variability between 10 and 116 m height from the regional reanalysis COSMO-REA6 compared to wind mast measurements over Northern Germany and the Netherlands

2016 ◽  
Vol 13 ◽  
pp. 151-161 ◽  
Author(s):  
Michael Borsche ◽  
Andrea K. Kaiser-Weiss ◽  
Frank Kaspar
Keyword(s):  
Wind Speed ◽  
The Netherlands ◽  
Diurnal Cycle ◽  
Correlation Coefficients ◽  
Wind Fields ◽  
Northern Germany ◽  
Significance Level ◽  
The North ◽  
The Mean ◽  
Regional Reanalysis

Abstract. Hourly and monthly mean wind speed and wind speed variability from the regional reanalysis COSMO-REA6 is analysed in the range of 10 to 116 m height above ground. Comparisons with independent wind mast measurements performed between 2001 and 2010 over Northern Germany over land (Lindenberg), the North Sea (FINO platforms), and The Netherlands (Cabauw) show that the COSMO-REA6 wind fields are realistic and at least as close to the measurements as the global atmospheric reanalyses (ERA20C and ERA-Interim) on the monthly scale. The median wind profiles of the reanalyses were found to be consistent with the observed ones. The mean annual cycles of variability are generally reproduced from 10 up to 116 m in the investigated reanalyses. The mean diurnal cycle is represented qualitatively near the ground by the reanalyses. At 100 m height, there is little diurnal cycle left in the global and regional reanalyses, though a diurnal cycle is still present in the measurements over land. Correlation coefficients between monthly means of the observations and the reanalyses range between 0.92 at 10 m and 0.99 at 116 m, with a slightly higher correlation of the regional reanalyses at Lindenberg at 10 m height which is significant only at a lower than 95 % significance level. Correlations of daily means tend to be higher for the regional reanalysis COSMO-REA6. Increasing temporal resolution further, reduces this advantage of the regional reanalysis. At around 100 m, ERA-Interim yields a higher correlation at Lindenberg and Cabauw, whereas COSMO-REA6 yields a higher correlation at FINO1 and FINO2.

scholarly journals Local Climate Zone Classification Scheme Can Also Indicate Local-Scale Urban Ventilation Performance: An Evidence-Based Study

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 776 ◽  
Author(s):  
Ziqi Zhao ◽  
Lidu Shen ◽  
Liguang Li ◽  
Hongbo Wang ◽  
Bao-Jie He
Keyword(s):  
Wind Speed ◽  
Classification Scheme ◽  
Local Scale ◽  
Evidence Based ◽  
Weather Station ◽  
Local Climate ◽  
Mean Wind Speed ◽  
The Mean ◽  
Ventilation Performance ◽  
Local Climate Zone

Studies on urban ventilation indicate that urban ventilation performance is highly dependent on urban morphology. Some studies have linked local-scale urban ventilation performance with the local climate zone (LCZ) that is proposed for surface temperature studies. However, there is a lack of evidence-based studies showing LCZ ventilation performance and affirming the reliability of using the LCZ classification scheme to demonstrate local-scale urban ventilation performance. Therefore, this study aims to analyse LCZ ventilation performances in order to understand the suitability of using the LCZ classification scheme to indicate local-scale urban ventilation performance. This study was conducted in Shenyang, China, with wind information at 16 weather stations in 2018. The results indicate that the Shenyang weather station had an annual mean wind speed of 2.07 m/s, while the mean wind speed of the overall 16 stations was much lower, only 1.44 m/s in value. The mean wind speed at Shenyang weather station and the 16 stations varied with seasons, day and night and precipitation conditions. The spring diurnal mean wind was strong with the speeds of 3.56 m/s and 2.21 m/s at Shenyang weather station and the 16 stations, respectively. The wind speed (2.21 m/s at Shenyang weather station) under precipitation conditions was higher than that (1.75 m/s at Shenyang weather station) under no precipitation conditions. Downtown ventilation performance was weaker than the approaching wind background, where the relative mean wind speed in the downtown area was only 0.53, much less than 1.0. The downtown ventilation performance also varied with seasons, day and night and precipitation conditions, where spring diurnal downtown ventilation performance was the weakest and the winter nocturnal downtown ventilation performance was the strongest. Moreover, the annual mean wind speed of the 16 zones decreased from the sparse, open low-rise zones to the compact midrise zones, indicating the suitability of using LCZ classification scheme to indicate local-scale urban ventilation performance. The high spatial correlation coefficients under different seasons, day and night and precipitation conditions, ranging between 0.68 and 0.99, further affirmed that LCZ classification scheme is also suitable to indicate local-scale urban ventilation performance, despite without the consideration of street structure like precinct ventilation zone scheme.

Experimental investigation of aerodynamic vibrations of solar wing system

2018 ◽  
Vol 21 (15) ◽  
pp. 2217-2226 ◽  
Author(s):  
YC Kim ◽  
Y Tamura ◽  
A Yoshida ◽  
T Ito ◽  
W Shan ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Solar Panels ◽  
Boundary Layer Flows ◽  
Turbulence Flow ◽  
Aeroelastic Model ◽  
Mean Wind Speed ◽  
The Mean

The general characteristics of aerodynamic vibrations of a solar wing system were investigated through wind tunnel tests using an aeroelastic model under four oncoming flows. In total, 12 solar panels were suspended by cables and orientated horizontally. Distances between panels were set constant. Tests showed that the fluctuating displacement increases proportionally to the square of the mean wind speed for all wind directions in boundary-layer flows. Larger fluctuating displacements were found for boundary-layer flows with larger power-law indices. Under low-turbulence flow, the fluctuating displacement increased proportionally to the square of the mean wind speed for wind directions between 0° and 30°, but an instability vibration was observed at high mean wind speed for wind directions larger than 40°. And when the wind direction was larger than 60°, a limited vibration was observed at low mean wind speed and the instability vibration was also observed at high mean wind speed. Fluctuating displacements under grid-generated flow showed a similar trend to that of the boundary-layer flows, although the values became much smaller.

Wind Speed Change and Influence on Wind Energy in Recent 50 Years over Hexi Corridor

2014 ◽  
Vol 1070-1072 ◽  
pp. 284-290
Author(s):  
Yao Zong Zhang ◽  
Bo Zhang ◽  
Yan Yan Liu
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Nonparametric Test ◽  
Test Methods ◽  
Hexi Corridor ◽  
Mean Wind Speed ◽  
Seasonal Wind ◽  
Speed Change ◽  
The Mean ◽  
Different Characteristics

Based on wind speed data of 13 meteorological stations in 1958-2012,Mann-Kendall nonparametric test methods was been used to study on wind speed changes in Hexi Corridor.Spatial and temporal characteristics of seasonal and monthly wind speed changes was examined. (1) The maximum wind speed appeared in the higher elevations of study area, such as Wushaoling and Mazongshan station. From east to west mean wind speed increased in Hexi Corridor.For nearly 50 years wind speed had showed decreasing trend. (2)In each season Spring with an maximum mean wind speed was 3.4m/s,the Summer mean wind speed was 2.9 m/s,Autumn mean wind speed was 2.6 m/s,the mean Winter wind speed was 2.8m/s.The seasonal wind speed mainly had decline trend, each station.has different characteristics trends (3) Mean wind speed in each month was greater than 2.5m/s,maximum monthly wind speed appeared in April was 3.5m/s,the minimum wind speed appeared in the September-October was 2.53m/s,the wind speed in March,April and May was greater than the November month,December,January.In addition to Mazongshan and Wushaoling,other station monthly wind speed showed a decreasing trend.Monthly mean wind speed in Jiuquan,Dingxin and Zhangye was slow decreasing trend.Anxi,Yumen wind decreasing trend were more obvious.(4)Wind decreasing trend will have a significant impact on wind energy, wind speed changes and wind energy should be evaluated in the future.

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

2016 ◽  
Vol 20 (10) ◽  
pp. 1599-1611 ◽  
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.

scholarly journals Observational Study of Nisarg Cyclone Winds using Phased Array Doppler Sodar at Atigre, Kolhapur, India

2021 ◽  
Author(s):  
Rani P. Pawar ◽  
Thiyagesan dharmaraj ◽  
Dada P. Nade ◽  
Mahendra N. Patil ◽  
Omkar M. Patil ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Phased Array ◽  
Vertical Wind Shear ◽  
Longwave Radiation ◽  
Western Coast ◽  
Sodar Data ◽  
The North ◽  
Doppler Sodar ◽  
Mean Wind Speed

Abstract One of the most important parameters in meteorology is the mean wind profile in the tropical cyclone boundary layer. The signature of the Nisarg cyclone is reported in the Phased Array Doppler Sound Detection and Ranging (SODAR) data installed at the Center for Space and Atmospheric Science (CSAS), Sanjay Ghodawat University, Kolhapur (16.74° N, 74.37° E; near India's western coast). The vertical profile of wind speed and wind direction measured from the sodar system clearly reveals the signature of Nisarg cyclone during 2- 3 June 2020. Our analysis revealed that, the maximum mean wind speed was 17 m/s on 3rd June 2020 at 10:00 IST. It also shows the change in the wind direction from southwest to southeast on 2nd June 2020 and 3rd June 2020. Daily high-resolution reanalysis in the domain, 0-25°N, 65-110°E, during the period from 31st May-5th June 2020 shown the variation in atmospheric pressure of the Nisarg cyclone from 1000 to 1008 hPa, sea surface tremperature (SST) between 30 and 31°C, outgoing longwave radiation (OLR) varied between 100 and 240 Wm−2, wind speed between 3 and 15 m/s and low values of vertical wind shear (VWS) was observed to the north of the track Nisarg. These findings could aid in better understanding and forecasting in this region. The present results are initial measurements of sodar system.

scholarly journals Spreadsheet solution for the computation of the mean wind speed and turbulence intensity profiles according to the Romanian standard

2019 ◽  
Vol 85 ◽  
pp. 03002
Author(s):  
Elena-Alexandra Chiulan ◽  
Andrei-Mugur Georgescu ◽  
Costin-Ioan Coşoiu ◽  
Anton Anton
Keyword(s):  
Wind Speed ◽  
Turbulence Intensity ◽  
Structural Design ◽  
Input Data ◽  
Wind Speed Profile ◽  
Wind Action ◽  
Design Engineers ◽  
Mean Wind Speed ◽  
Wind Characteristics ◽  
The Mean

The presented paper focuses on the computation of the mean wind speed and turbulence intensity profiles for all the cities from Romania. The calculation of both, the mean wind speed profile and the turbulence intensity profile, had as mathematical support the equations presented in the Romanian design standard for wind action CR 1-1-4/2012. The main objective of this paper was to provide a tool for the computation of the two wind action features. This method was based on creating a spreadsheet in Excel with which, in just a few seconds, a user could correctly obtain the two wind characteristics. This Excel dashboard can be used as a teaching material for students as well as input data for structural design engineers in the process of modelling and observing the behaviour of a building excited by wind action on a particular city in Romania.

Sign in / Sign up

Export Citation Format

Share Document