Anemometer Tower Research Articles

Time resolution of wind speed data introduces errors in wind power density assessment

Wind energy is critical in the global shift towards renewable energy sources, necessitating accurate potential assessments for informed decision-making and strategic development in this transition. Despite the widespread use of wind speed data with varying time resolutions for estimating wind energy, the influence of this variability on the accuracy of wind energy assessment remains uncertain. In this study, we investigate the impact of wind speed data’s time resolution on wind power density (WPD) assessment, utilizing high-frequency, in-situ observations collected from eight anemometer towers in China. Through analysis of wind speed data at nine resolutions, ranging from 10-minute to monthly intervals, we uncover significant errors introduced by coarser time resolutions in WPD calculations. Specifically, it reveals a systematic underestimation of WPD with decreasing time resolution, highlighting the importance of time resolution in wind energy evaluation. While hourly wind speed data yield acceptable WPD errors, daily and monthly resolutions lead to substantial underestimation due to the smoothing effect of fluctuations. We also delve into the underlying mechanisms contributing to these errors, including variations in the power law exponent and changes in the Weibull distribution shape factor with time resolution. Furthermore, we propose a novel method to mitigate WPD calculation errors using coarse time resolution data by regressing Weibull distribution factors. The findings offer valuable insights into wind speed data selection and accurate wind energy assessment, with implications for renewable energy planning and policy-making in the context of the global energy transition.

Wind Shear Model Considering Atmospheric Stability to Improve Accuracy of Wind Resource Assessment

An accurate wind shear model is an important prerequisite in extrapolating the wind resource from lower heights to the increasing hub height of wind turbines. Based on the 1-year dataset (collected in 2014) consisting of 15-minute intervals collected at heights of 2, 10, 50, 100, and 150 m on an anemometer tower in northern China, the present study focuses on the time-varying relationship between the wind shear coefficient (WSC) and atmospheric stability and proposes a wind shear model considering atmospheric stability. Through the relationship between Monin–Obukhov (M-O) length and gradient Richardson number, the M-O length is directly calculated by wind data, and the WSC is calculated by combining the Panofsky and Dutton (PD) models, which enhances the engineering practicability of the model. Then, the performance of the model is quantified and compared with two alternative methods: the use of annual average WSC and the use of stability change WSC extrapolation. The analysis demonstrates that the proposed model outperforms the other approaches in terms of normal root mean square error (NRMSE) and normal bias (NB). More specifically, this method reduces the NRMSE and NB by 24–29% and 76–95%, respectively. Meanwhile, it reaches the highest extrapolation accuracy under unstable and stable atmospheric conditions. The results are verified using the Weibull distribution.

<i>Corrigendum to</i>: Atmospheric turbulent structures and fire sweeps during shrub fires and implications for flaming zone behaviour

<sec> Background Wildfires propagate through vegetation exhibiting complex spread patterns modulated by ambient atmospheric wind turbulence. Wind gusts at the fire-front extend and intensify flames causing direct convective heating towards unburnt fuels resulting in rapid acceleration of spread. </sec> <sec> Aims To characterise ambient and fire turbulence over gorse shrub and explore how this contributes to fire behaviour. </sec> <sec> Methods Six experimental burns were carried out in Rakaia, New Zealand under varying meteorological conditions. The ignition process ensured a fire-line propagating through dense gorse bush (1 m high). Two 30-m sonic anemometer towers measured turbulent wind velocity at six different levels above the ground. Visible imagery was captured by cameras mounted on uncrewed aerial vehicles at 200 m AGL. </sec> <sec> Key results Using wavelet decomposition, we identified different turbulent time scales that varied between 1 and 128 s relative to height above vegetation. Quadrant analysis identified statistical distributions of atmospheric sweeps (downbursts of turbulence towards vegetation) with sustained events emanating from above the vegetation canopy and impinging at the surface with time scales up to 10 s. </sec> <sec> Conclusions Image velocimetry enabled tracking of ‘fire sweeps’ and characterised for the first time their lifetime and dynamics in comparison with overlying atmospheric turbulent structures. </sec> <sec> Implications This methodology can provide a comprehensive toolkit when investigating coupled atmosphere–fire interactions. </sec>

Research on Representative Engineering Applications of Anemometer Towers Location in Complex Topography Wind Resource Assessment

The typical location and number of anemometer towers in the assessed area are the key to the accuracy of wind resource assessment in complex topography. As calculation examples, this paper used two typical complex topography wind farms in Guangxi, Yunnan province in China. Firstly, we simulated the wind resource status of the anemometer tower in the Meteodyn WT software. Secondly, we compared the simulated wind resource with the actual measured data by the anemometer tower in the same situation. Thirdly, we analyzed the influence of anemometer tower location and quantity in the accuracy of wind resource assessment through the comparison results. The results showed that the range which the anemometer tower can represent is limited (

Microscale Wind Assessment, Comparing Mesoscale Information and Observed Wind Data

One of the most common problems in wind resource assessment is that measured data are not always available at the site of interest. That is why, in several studies, reanalysis data have been used as an alternative, which, in some cases, have been validated by measured data. Mexico is no exception, since there are not many measurement towers in the country that provide valid records throughout the country. In view of the above, in this study a comparison was made between the measurements observed in six anemometric towers, located in different locations in the United Mexican States; data from the MERRA-2 and ERA-5 reanalysis; and data from the generalized wind climates (GWC), available in the Global Wind Atlas. The study was conducted at 80 m, which is the highest height at which data were recorded on the measurement towers at each site. In the case of the MERRA-2 and ERA-5 data, extrapolation of the data series to 80 m was required. In the case of the towers, a comparison of the two data sets measured at 80 m and the height at which two anemometers were available, was performed. This analysis was supported by Windographer version 4 software designed by the company UL solutions, from which *.tab files were exported at 80 m, which were then imported from the WAsP 10.0 program to perform the microscale modeling. The comparison variable was the mean power density, for which the relative deviations between the measured values and those obtained from the reanalysis data and the GWCs were determined. For a better interpretation of the relative errors calculated, an analysis of the orographic characteristics of all the sites was performed using the roughness index (RIX). The results obtained showed that the behavior of the reanalysis and the GWC data was not homogeneous in the sites studied; therefore, an adequate relationship between the magnitudes of the ΔRIX and the relative deviations was not observed, especially for the ERA5 and GWC. The ERA5 data were the furthest from the measured data, with relative deviations greater than 50% at five of the six sites; however, the MERRA-2 and GWC data were the closest to the measured data. The MERRA-2 data showed deviations of less than 11%, except at the La Venta site, where it was 29.5%—a site where the GWC also had a high deviation of 139.4%. The latter is attributable to the effects caused by the nearby wind farms on the wind flow measured by the La Venta station. In general, the MERRA-2 data are an alternative to performing a pre-analysis of the wind resource in Mexico.

Atmospheric turbulent structures and fire sweeps during shrub fires and implications for flaming zone behaviour

Background Wildfires propagate through vegetation exhibiting complex spread patterns modulated by ambient atmospheric wind turbulence. Wind gusts at the fire-front extend and intensify flames causing direct convective heating towards unburnt fuels resulting in rapid acceleration of spread. Aims To characterise ambient and fire turbulence over gorse shrub and explore how this contributes to fire behaviour. Methods Six experimental burns were carried out in Rakaia, New Zealand under varying meteorological conditions. The ignition process ensured a fire-line propagating through dense gorse bush (1 m high). Two 30-m sonic anemometer towers measured turbulent wind velocity at six different levels above the ground. Visible imagery was captured by cameras mounted on uncrewed aerial vehicles at 200 m AGL. Key results Using wavelet decomposition, we identified different turbulent time scales that varied between 1 and 128 s relative to height above vegetation. Quadrant analysis identified statistical distributions of atmospheric sweeps (downbursts of turbulence towards vegetation) with sustained events emanating from above the vegetation canopy and impinging at the surface with time scales up to 10 s. Conclusions Image velocimetry enabled tracking of ‘fire sweeps’ and characterised for the first time their lifetime and dynamics in comparison with overlying atmospheric turbulent structures. Implications This methodology can provide a comprehensive toolkit when investigating coupled atmosphere–fire interactions.

Restoration of Wind Speed in Qinzhou, Guangxi during Typhoon Rammasun

In 2014, Typhoon Rammasun invaded Qinzhou, Guangxi, causing damage to the wind tower sensor at 80 m in Qinzhou. In order to restore the wind speed at 80 m at that time, this paper was based on the hourly average wind speed data of the wind tower and meteorological station from 2017–2019, and constructed the wind speed related model of Meteorological Station and the wind measuring tower in Qinzhou, Moreover, this paper Based on the hourly average wind speed data of Qinzhou Meteorological Station in 2014, Restored the hourly average wind speed of the anemometer tower during Rammasun landfalled. The results showed it is significant correlation that the hourly mean wind speed of the wind tower at 80 m and the hourly mean wind speed of meteorological station at 100 m (R2 = 0.9632), and speed of the wind measuring tower and speed of meteorological station constitutes an equation, This equation is Y = 0.7834X. The hourly average wind speed of the wind tower at 80 m during the 2014 Rammasun Landing was restored using this model. See the results in Schedule 4.

Favorable wind states in wind energy production at La Rumorosa I wind farm

This work introduces a statistical method that identifies wind states present in the wind farm La Rumorosa by analyzing wind speed and nacelle position (wind direction). These states contribute to the generation of wind power in microscale, mesoscale, and macroscale phenomena. The data were obtained from five wind turbines at the onshore and anemometric tower in La Rumorosa located on the border with the state of California, USA. The contribution of wind states and their impact on the annual power production in the wind farm was observed using this method. It is concluded that the method reliably identifies wind patterns with low computational effort.

Avaliação da previsão de estabilidade na camada atmosférica de superfície do modelo WRF e efeitos na previsão de geração eólica no Uruguai

This work evaluates forecasts of vertical stability of the surface atmospheric layer obtained with the WRF regional model in Uruguay, for different times of the day and seasons of the year. The temperature and humidity values obtained from the model outputs and from field measurements at different heights in an anemometric tower allow to calculate the vertical gradient of virtual static stability both for predictions and field measurements. With the results obtained, it was possible to know the behavior of the WRF model in relation to the stability of the surface layer, which is closely related to the wind potential that may exist at different times of the day. In this way, a possible relationship between the systematic errors of forecasts of wind power and surface layer stability in Uruguay can be proposed.

Simulation of Wind Speed Based on Different Driving Datasets and Parameterization Schemes Near Dunhuang Wind Farms in Northwest of China

In this study, we evaluate the impacts of different datasets (e.g., NCEP global forecast system (GFS) and ERA5) that are used to derive the initial and boundary conditions, various planetary parameterization boundary layer (PBL) schemes and radiation parameterization schemes on wind speed simulations over wind farms near Dunhuang in Northwest of China. The mesoscale community Weather Research and Forecasting (WRF) model is employed to simulate the wind speeds in March of 2014. The sensitivity of numerical simulations to different PBL schemes, including the Yonsei University (YSU), the Asymmetric Convective Model (ACM2) and the Mellor–Yamada–Janjic (MYJ) scheme are examined. Besides, simulations with different radiation parameterization schemes, including the Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG) and the Fu–Liou–Gu radiative transfer scheme (FLG), are compared. Based on hourly observation data from three national basic meteorological observing stations and an anemometer tower in Dunhuang, the simulation results are evaluated. Results show that, using the GFS data as the initial data, the simulation error of 10-m wind speed is rather smaller under the combination of the YSU and FLG. When using the ERA5 data as the initial data, the error of the 2-m temperature simulation is smaller, and it is also less than that of the 10-m wind speed simulation. The simulation results show significant differences at different altitudes. The relative error of wind speed is larger at higher altitude. In the vertical direction, the wind speed is smaller at a lower height and so is the simulation error. In terms of wind speed from the anemometer tower, the error of the wind speed is related to the magnitude of the observed wind speed. Therefore, according to specific conditions of the simulated area, selecting an appropriate combination of initial data and parameterization schemes can effectively reduce the errors of simulated wind speed.

Short-term forecast of wind speed through mathematical models

The predictability of wind information in a given location is essential for the evaluation of a wind power project. Predicting wind speed accurately improves the planning of wind power generation, reducing costs and improving the use of resources. This paper seeks to predict the mean hourly wind speed in anemometric towers (at a height of 50 m) at two locations: a coastal region and one with complex terrain characteristics. To this end, the Holt–Winters (HW), Artificial Neural Networks (ANN) and Hybrid time-series models were used. Observational data evaluated by the Modern-Era Retrospective analysis for Research and Applications-Version 2 (MERRA-2) reanalysis at the same height of the towers. The results show that the hybrid model had a better performance in relation to the others, including when compared to the evaluation with MERRA-2. As such, the hybrid models are a good method to forecast wind speed data for wind generation.

Wind Resource Assessment on Puná Island

Puná Island, located in the Pacific Ocean off the southern coast of Ecuador, has a population of approximately 3344 inhabitants. However, not all inhabitants have access to electricity, which is largely supplied by diesel generators. Therefore, to identify a renewable, sustainable, environmentally friendly and low-cost alternative, a 40-m-high anemometer tower was installed for wind resource assessment and to determine the possibility of generating electricity from wind energy. Based on mathematical models for electricity generation from wind energy, data were analyzed using the software Windographer and WAsP, to determine a long-term wind speed of 4.8 m/s and a mean wind power density of 272 W/m2. By simulating the use of a 3.3-MW wind turbine, we demonstrated that as much as 800 kWh could be generated during the hours when the wind reaches its highest speed. In addition to demonstrating the technical feasibility of meeting the electricity demands of Puná Island through wind power, this study exemplifies a method that can be used for wind resource assessment in any location.

An approach to model extreme wind speed distributions using the Weather Research and Forecasting model

The aim of this study was to generate hourly mean monthly maximum wind speed return period curves for heights 60 m above the ground using Weather Research and Forecasting modeled data. The methodology introduced produces long-term wind speed data in places where the available measured series for such heights are not long enough for a correct extreme value analysis. Climate Forecast System Reanalysis data are used as input for the Weather Research and Forecasting simulations, providing information for the period 1979–2015. The modeled results are compared with wind speed series measured in anemometric towers, available for the period 2008–2015. Weather Research and Forecasting output is then adjusted to model properly the wind speed at the measuring sites. A good representation of the cumulative distribution of monthly maxima was reached after applying a double linear adjustment.

Issue: Selected paper of OIPE 2016 on modeling and optimal design of electromagnetic and electronic devices

Issue: Selected paper of OIPE 2016 on modeling and optimal design of electromagnetic and electronic devices

Analyzing the turbulent planetary boundary layer by remote sensing systems: the Doppler wind lidar, aerosol elastic lidar and microwave radiometer

Abstract. The planetary boundary layer (PBL) is the lowermost region of troposphere and is endowed with turbulent characteristics, which can have mechanical and/or thermodynamic origins. This behavior gives this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies of turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (instrumentation aboard an aircraft). Ground-based remote sensing, both active and passive, offers an alternative for studying the PBL. In this study we show the capabilities of combining different remote sensing systems (microwave radiometer – MWR, Doppler lidar – DL – and elastic lidar – EL) for retrieving a detailed picture on the PBL turbulent features. The statistical moments of the high frequency distributions of the vertical wind velocity, derived from DL, and of the backscattered coefficient, derived from EL, are corrected by two methodologies, namely first lag correction and -2/3 law correction. The corrected profiles, obtained from DL data, present small differences when compared with the uncorrected profiles, showing the low influence of noise and the viability of the proposed methodology. Concerning EL, in addition to analyzing the influence of noise, we explore the use of different wavelengths that usually include EL systems operated in extended networks, like the European Aerosol Research Lidar Network (EARLINET), Latin American Lidar Network (LALINET), NASA Micro-Pulse Lidar Network (MPLNET) or Skyradiometer Network (SKYNET). In this way we want to show the feasibility of extending the capability of existing monitoring networks without strong investments or changes in their measurements protocols. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases we discuss results provided by the different instruments showing their complementarity and the precautions to be applied in the data interpretation. Our study shows that the use of EL at 532 nm requires a careful correction of the signal using the first lag time correction in order to get reliable turbulence information on the PBL.

Investigation of a downburst loading event on a full-scale low-rise building

This paper details a downburst event that occurred on June 19, 2003, where both wind and wind-induced pressure data were recorded at the Texas Tech University Wind Engineering Research Field Laboratory (WERFL). This event displayed rapid changes in wind speed (i.e. ramp-up and ramp-down) and wind direction over a period of approximately 30 s. The event also exhibited an atypical vertical wind profile with a peak measured wind speed occurring at 4 m and wind direction changes up to 30 deg over the 50 m anemometer tower height. Wind loading on the WERFL building also displayed ramp-up and ramp-down behavior. When converting these data to pressure coefficients (Cp,3), non-stationary pressures were normalized by a 3-s wind speed, which was shifted by a time lag to account for the spatial separation between building and tower. Differences were discovered in Cp,3 between ramp-up and ramp-down periods. To ascertain any differences between downburst loading and that induced by atmospheric boundary layer (ABL) wind fields, loading characteristics were compared in the same fashion with 128 ABL events at WERFL. Analysis of the comparisons concluded that downburst Cp,3 values mostly stayed within the bounds of the ABL, however fluctuate between extrema of ABL distributions. A significant difference between ramp-up and ramp-down periods was further solidified as ramp-up (ramp-down) Cp,3 values were lower (higher) than expected in the ABL. A physical explanation for these differences is unclear, and further study is needed to ascertain its validity.

Research on Wind Field Characteristics of High-Altitude Area in Tibet

Tibet is rich in clean energy such as solar energy, wind energy and water energy. But the region also has environment characteristics such as high altitude, low pressure and strong radiation, and it is very different from the wind field characteristics of transmission lines in low altitude area. In order to define the wind field characteristics along the transmission lines, this paper analyzes the meteorological modes of the two wind fields with densely-deployed transmission lines; verifies the mode analysis results based on the actually measured data of meteorological stations and gradient anemometer towers; and on the basis of ensuring the accuracy and reliability of mode analysis results, further analyzes the change law of wind speed and wind speed profile in recurrence interval of high-altitude area, and provides relevant design parameters for construction of transmission lines in this area.

Wind Power in Girau do Ponciano, Alagoas, Brazil Using Anemometric Data and Microscale Modeling

Abstract The wind potential in the Agreste region of Northeastern Brazil has important features for energy exploration, but, stills unexplored. This work analyzes 3.1 yrs anemometer tower measurements in the Girau do Ponciano, Alagoas state. The observational data was recorded from October 2007 to October 2010. Three periods were defined to constrain the seasonal wind patterns: Annual, Dry (October-January) and Wet (May-August). Hourly and monthly series showed the average wind speed was higher than 7 m s-1, reaching 8.5 m s-1 during the dry season. Further, the wind direction was also favorable with less variability, concentrated between NE and SE. During nighttime the wind speed ≥ 10 m s-1 were more frequent. The Weibull fit is more distributed (concentrated) during the dry (wet) season close to 8 m s-1 (7 m s-1). The AEP (Cf) parameter estimated by the WAsP model varied between 3 to 10 GWh (35% to 65%). Nevertheless, Girau do Ponciano domain was positioned nearby two highways and close to an electrical substation in the Arapiraca city. Other geographic conditions (topography inclination < 15°, the absence of obstacles, and low vegetation) are also favorable to future wind farm installation in this area.

Perfil do vento e estabilidade atmosférica próxima da superfície no Centro de Lançamento de Alcântara

Wind and atmospheric stability are fundamental for aerospace research and development activities at the Alcântara Launch Center, situated in the Maranhão Brazilian state. The physical processes related to these meteorological parameters during the dry season are well known. However, there is still gap concerning the rainy season. The data obtained in the anemometric tower are here studied considering vertical profiles of wind and temperature, and the Richardson bulk number. The mechanical characteristics showed weaker vertical gradient during the daytime-nighttime transition. A primary reason of that behaviour is the sea breeze from 60 m height of the tower. Those near-surface winds are more intense at night in the rainy season. As expected, the surface layer tends to be statically neutral throughout the daytime cycle in the dry season. Meanwhile, this stability classification was seen more frequently at the nighttime in the rainy season. Rainfall events along wet months were typically nocturnal. The deeper convective cells and its derived downdrafts help to understand this behavior. Due to -40% precipitation anomaly reported in this rainy season, these results may have been a direct response to this condition. In future studies, turbulent measurements are required to investigate how the thermodynamic and mechanical pertubations interacts with the rainfall stability patterns during the wet season.

Análise espacial dos ventos no Centro de Lançamento de Alcântara, Maranhão

The wind at the Alcântara Launch Center (ALC), which presents as main characteristics an oceanic behavior, influenced by the trade winds and the sea breeze, and modified by the ocean-continent interface and local topography. Therefore, it is necessary to study the characteristics of the site flow, highlighting the influence of the surface boundary layer and the validity of the surface flow homogeneity. In this study will be used the data of two anemometric towers installed in the ALC to evaluate spatial differences in the characteristics of the average wind and its daily cycle. For comparison, data from the ERA5 reanalysis, the fifth generation created by European Centre for Medium-Range Weather Forecasts (ECMWF). The results show that the anemometric towers present, on average, similar characteristics and that the data from the reanalysis can be used for studies of mesoscale atmospheric phenomena that occur on the surface.