scholarly journals Wind Estimation in the Lower Atmosphere Using Multirotor Aircraft

2017 ◽  
Vol 34 (5) ◽  
pp. 1183-1191 ◽  
Author(s):  
Ross T. Palomaki ◽  
Nathan T. Rose ◽  
Michael van den Bossche ◽  
Thomas J. Sherman ◽  
Stephan F. J. De Wekker
Keyword(s):  
Wind Speed ◽  
Sonic Anemometer ◽  
Unmanned Aircraft ◽  
Lower Atmosphere ◽  
Promising Alternative ◽  
Atmospheric Structure ◽  
Structure And Dynamics ◽  
Sonic Anemometers ◽  
Vertical Profiling ◽  
Good Agreement

AbstractUnmanned aerial vehicles are increasingly used to study atmospheric structure and dynamics. While much emphasis has been on the development of fixed-wing unmanned aircraft for atmospheric investigations, the use of multirotor aircraft is relatively unexplored, especially for capturing atmospheric winds. The purpose of this article is to demonstrate the efficacy of estimating wind speed and direction with 1) a direct approach using a sonic anemometer mounted on top of a hexacopter and 2) an indirect approach using attitude data from a quadcopter. The data are collected by the multirotor aircraft hovering 10 m above ground adjacent to one or more sonic anemometers. Wind speed and direction show good agreement with sonic anemometer measurements in the initial experiments. Typical errors in wind speed and direction are smaller than 0.5 and 30°, respectively. Multirotor aircraft provide a promising alternative to traditional platforms for vertical profiling in the atmospheric boundary layer, especially in conditions where a tethered balloon system is typically deployed.

scholarly journals Field intercomparison of prevailing sonic anemometers

2018 ◽  
Vol 11 (1) ◽  
pp. 249-263 ◽  
Author(s):  
Matthias Mauder ◽  
Matthias J. Zeeman
Keyword(s):  
Wind Speed ◽  
Sonic Anemometer ◽  
Three Dimensional ◽  
Buoyancy Flux ◽  
Horizontal Wind ◽  
Horizontal Wind Speed ◽  
Sonic Anemometers ◽  
Adjacent Structures ◽  
Mean Wind Speed ◽  
Field Intercomparison

Abstract. Three-dimensional sonic anemometers are the core component of eddy covariance systems, which are widely used for micrometeorological and ecological research. In order to characterize the measurement uncertainty of these instruments we present and analyse the results from a field intercomparison experiment of six commonly used sonic anemometer models from four major manufacturers. These models include Campbell CSAT3, Gill HS-50 and R3, METEK uSonic-3 Omni, R. M. Young 81000 and 81000RE. The experiment was conducted over a meadow at the TERENO/ICOS site DE-Fen in southern Germany over a period of 16 days in June of 2016 as part of the ScaleX campaign. The measurement height was 3 m for all sensors, which were separated by 9 m from each other, each on its own tripod, in order to limit contamination of the turbulence measurements by adjacent structures as much as possible. Moreover, the high-frequency data from all instruments were treated with the same post-processing algorithm. In this study, we compare the results for various turbulence statistics, which include mean horizontal wind speed, standard deviations of vertical wind velocity and sonic temperature, friction velocity, and the buoyancy flux. Quantitative measures of uncertainty, such as bias and comparability, are derived from these results. We find that biases are generally very small for all sensors and all computed variables, except for the sonic temperature measurements of the two Gill sonic anemometers (HS and R3), confirming a known transducer-temperature dependence of the sonic temperature measurement. The best overall agreement between the different instruments was found for the mean wind speed and the buoyancy flux.

scholarly journals Intercomparison of Small Unmanned Aircraft System (sUAS) Measurements for Atmospheric Science during the LAPSE-RATE Campaign

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2179 ◽  
Author(s):  
Lindsay Barbieri ◽  
Stephan Kral ◽  
Sean Bailey ◽  
Amy Frazier ◽  
Jamey Jacob ◽  
...  
Keyword(s):  
Wind Speed ◽  
Measurement Data ◽  
Mean Value ◽  
Radiation Shielding ◽  
Unmanned Aircraft ◽  
Lapse Rate ◽  
Value Differences ◽  
Sonic Anemometers ◽  
Challenges And Opportunities ◽  
Aircraft System

Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric measurement data from the Lower Atmospheric Process Studies at Elevation—a Remotely piloted Aircraft Team Experiment (LAPSE-RATE) field campaign. We evaluate a total of 38 individual sUAS with 23 unique sensor and platform configurations using a meteorological tower for reference measurements. We assess precision, bias, and time response of sUAS measurements of temperature, humidity, pressure, wind speed, and wind direction. Most sUAS measurements show broad agreement with the reference, particularly temperature and wind speed, with mean value differences of 1.6 ± 2.6 ∘ C and 0.22 ± 0.59 m/s for all sUAS, respectively. sUAS platform and sensor configurations were found to contribute significantly to measurement accuracy. Sensor configurations, which included proper aspiration and radiation shielding of sensors, were found to provide the most accurate thermodynamic measurements (temperature and relative humidity), whereas sonic anemometers on multirotor platforms provided the most accurate wind measurements (horizontal speed and direction). We contribute both a characterization and assessment of sUAS for measuring atmospheric parameters, and identify important challenges and opportunities for improving scientific measurements with sUAS.

scholarly journals Can LiDARs Replace Meteorological Masts in Wind Energy?

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3680 ◽  
Author(s):  
Jay Prakash Goit ◽  
Susumu Shimada ◽  
Tetsuya Kogaki
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Turbulence Intensity ◽  
Regression Line ◽  
Sonic Anemometer ◽  
Bending Moments ◽  
Wind Speeds ◽  
Acceptable Accuracy ◽  
Sonic Anemometers ◽  
Measured Wind Speed

This paper discusses whether profiling LiDARs can replace meteorological tower-based wind speed measurement for wind energy applications without severely compromising accuracy. To this end, the accuracy of LiDAR is evaluated in a moderately complex terrain by comparing long-term wind data measured by a profiling LiDAR against those obtained from tower-mounted cup and sonic anemometers. The LiDAR-measured wind speeds show good agreement with those measured using the sonic anemometer, with the slope of regression line being 1.0 and R 2 > 0.99 . Furthermore, the turbulence intensity obtained from the LiDAR has better agreement with that from the sonic anemometer compared to the cup anemometer which showed the lowest turbulence intensities among the three devices. A comparison of the turbulence intensity obtained from the 90th percentile of the standard deviation distribution shows that the LiDAR-measured turbulence intensities are mostly larger (by 2% or less) than those measured by the sonic anemometer. The gust factors obtained from both devices roughly converged to 1.9, showing that LiDAR is able to measure peak wind speed with acceptable accuracy. The accuracy of the wind speed and power distributions measured using the profiling LiDAR are then evaluated by comparing them against the corresponding distributions obtained from the sonic anemometer. Furthermore, the annual capacity factor—for the NREL 5-MW wind turbine—from the LiDAR-measured wind speed is 2% higher than that obtained from the sonic anemometer-measured wind speed. Numerical simulations are performed using OpenFAST in order to compute fatigue loads for the wind speed and turbulence distributions for the LiDAR and the sonic anemometer measurements. It is found that the 20 years lifetime Damage Equivalent Loads (DELs) computed for the LiDAR wind speed were higher than those for the sonic anemometer wind speeds, by 2%–6% for the blade root bending moments and by 11%–13% for the tower base bending moments. This study shows that even with some shortcomings, profiling LiDARs can measure wind speeds and turbulence intensities with acceptable accuracy. Therefore, they can be used to analyze wind resource and wind power potential of prospective sites, and to evaluate whether those sites are suitable for wind energy development.

scholarly journals Comparison of turbulence measurements by a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar

2020 ◽  
Vol 13 (2) ◽  
pp. 969-983 ◽  
Author(s):  
Matthias Mauder ◽  
Michael Eggert ◽  
Christian Gutsmuths ◽  
Stefan Oertel ◽  
Paul Wilhelm ◽  
...  
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Friction Velocity ◽  
Sonic Anemometer ◽  
Vertical Wind ◽  
Doppler Lidar ◽  
Flow Distortion ◽  
Sonic Anemometers ◽  
Vertical Wind Speed ◽  
Standard Deviations

Abstract. Accurate measurements of turbulence statistics in the atmosphere are important for eddy-covariance measurements, wind energy research, and the validation of atmospheric numerical models. Sonic anemometers are widely used for these applications. However, these instruments are prone to probe-induced flow distortion effects, and the magnitude of the resulting errors has been debated due to the lack of an absolute reference instrument under field conditions. Here, we present the results of an intercomparison experiment between a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar, which is inherently free of any flow distortion. This novel remote sensing instrument has otherwise very similar spatial and temporal sampling characteristics to the sonic anemometer and hence served as a reference for this comparison. The presented measurements were carried out over flat homogeneous terrain at a measurement height of 30 m. We provide a comparative statistical analysis of the resulting mean wind velocities, the standard deviations of the vertical wind speed and the friction velocity and investigate the reasons for the observed deviations based on the turbulence spectra and co-spectra. Our results show an agreement of the mean wind velocity measurements and the standard deviations of the vertical wind speed with a comparability of 0.082 and 0.020 m s−1, respectively. Biases for these two quantities were 0.003 and 0.012 m s−1, respectively. Slightly larger differences were observed for friction velocity. Analysis of the corresponding co-spectra showed that the CSAT3B underestimates this quantity systematically by about 3 % on average as a result of co-spectral losses in the frequency range between 0.1 and 5 s−1. We also found that an angle-of-attack-dependent transducer-shadowing correction does not improve the agreement between the CSAT3B and the Physikalisch-Technische Bundesanstalt (PTB) lidar effectively.

scholarly journals Comparison of turbulence measurements by a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar

2019 ◽  
Author(s):  
Matthias Mauder ◽  
Michael Eggert ◽  
Christian Gutsmuths ◽  
Stefan Oertel ◽  
Paul Wilhelm ◽  
...  
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Friction Velocity ◽  
Sonic Anemometer ◽  
Vertical Wind ◽  
Doppler Lidar ◽  
Flow Distortion ◽  
Sonic Anemometers ◽  
Vertical Wind Speed ◽  
Standard Deviations

Abstract. Accurate measurements of turbulence statistics in the atmosphere are important for eddy-covariance measurements, wind energy research, and the validation of atmospheric numerical models. Sonic anemometers are widely used for these applications. However, these instruments are prone to probe-induced flow distortion effects, and the magnitude of the resulting errors has been debated due to the lack of an absolute reference instrument under field conditions. Here, we present the results of an intercomparison experiment between a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar, which is inherently free of any flow-distortion. This novel remote sensing instrument has otherwise very similar spatial and temporal sampling characteristics as the sonic anemometer and hence served as a reference for this comparison. The presented measurements were carried out over flat homogeneous terrain, at a measurement height of 30 m. We provide a comparative statistical analysis of the resulting mean wind velocities, the standard deviations of the vertical wind speed and the friction velocity and investigate the reasons for the observed deviations based on the turbulence spectra and cospectra. Our results show a very good agreement of the mean wind velocity measurements and the standard deviations of the vertical wind speed, with comparabilities of 0.082 and 0.017 m s−1, respectively. Biases for these two quantities were very low, being smaller than 0.01 m s−1, which corresponds to about 1 % in relative terms. Slightly larger differences were observed for friction velocity. Analysis of the corresponding cospectra showed that the CSAT3B underestimates this quantity systematically by about 3 % on average as a result of too steep a drop-off in the inertial sub-range. We also found that an angle-of-attack dependent transducer-shadowing correction does not improve this agreement effectively because it leads to an artificial correlation between the three wind components and therefore severely distorts the shape of the cospectra.

scholarly journals 3D Turbulence Measurements Using Three Synchronous Wind Lidars: Validation against Sonic Anemometry

2014 ◽  
Vol 31 (7) ◽  
pp. 1549-1556 ◽  
Author(s):  
Fernando Carbajo Fuertes ◽  
Giacomo Valerio Iungo ◽  
Fernando Porté-Agel
Keyword(s):  
Time Series ◽  
Velocity Vector ◽  
Measurement Techniques ◽  
Sonic Anemometer ◽  
Reynolds Stresses ◽  
Measurement Systems ◽  
Sonic Anemometers ◽  
Order Of Magnitude ◽  
Good Agreement ◽  
Three Components

Abstract This paper presents a technique to measure the time series of the three components of the wind vector at a point in space from synchronous measurements of three scanning Doppler wind lidars. Knowing the position of each lidar on the ground and the orientation of each laser beam allows for reconstructing the three components of the wind velocity vector. The laser beams must intersect at the desired point in space and their directions must be noncoplanar, so that trigonometric relationships allow the reconstruction of the velocity vector in any coordinate system. This technique has been tested during a measurement campaign carried out at Cabauw’s Experimental Site for Atmospheric Research (CESAR) in the Netherlands and compared against measurements from sonic anemometers installed in a meteorological mast. The spatial resolutions of both measurement techniques differ by one order of magnitude. Therefore, in order to properly compare the results, a pseudospatial filter that mimics the attenuation induced by the lidar technology at small scales of turbulence has been applied to the velocity time series provided by the sonic anemometer. Good agreement between both measurement systems is found in terms of the measured instantaneous velocity vector, turbulence statistics, Reynolds stresses, and the spectra of the three components of the velocity and the turbulent kinetic energy. These results provide a successful validation of the proposed technique.

scholarly journals Comparison of methods to derive radial wind speed from a continuous-wave coherent lidar Doppler spectrum

2018 ◽  
Vol 11 (11) ◽  
pp. 6339-6350 ◽  
Author(s):  
Dominique P. Held ◽  
Jakob Mann
Keyword(s):  
Wind Speed ◽  
Continuous Wave ◽  
Transfer Functions ◽  
Sonic Anemometer ◽  
Volume Averaging ◽  
Low Noise ◽  
Doppler Spectrum ◽  
Centroid Method ◽  
Wind Speeds ◽  
Sonic Anemometers

Abstract. Continuous-wave (cw) lidar systems offer the possibility to remotely sense wind speed but are also affected by differences in their measurement process compared to more traditional anemometry like cup or sonic anemometers. Their large measurement volume leads to an attenuation of turbulence. In this paper we study how different methods to derive the radial wind speed from a lidar Doppler spectrum can mitigate turbulence attenuation. The centroid, median and maximum methods are compared by estimating transfer functions and calculating root mean squared errors (RMSEs) between a lidar and a sonic anemometer. Numerical simulations and experimental results both indicate that the median method performed best in terms of RMSE and also had slight improvements over the centroid method in terms of volume averaging reduction. The maximum, even though it uses the least amount of information from the Doppler spectrum, performs best at mitigating the volume averaging effect. However, this benefit comes at the cost of increased signal noise due to discretisation of the maximum method. Thus, when the aim is to mitigate the effect of turbulence attenuation and obtain wind speed time series with low noise, from the results of this study we recommend using the median method. If the goal is to measure average wind speeds, all three methods perform equally well.

scholarly journals Identification of tower-wake distortions using sonic anemometer and lidar measurements

2017 ◽  
Vol 10 (2) ◽  
pp. 393-407 ◽  
Author(s):  
Katherine McCaffrey ◽  
Paul T. Quelet ◽  
Aditya Choukulkar ◽  
James M. Wilczak ◽  
Daniel E. Wolfe ◽  
...  
Keyword(s):  
Wind Speed ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Sonic Anemometer ◽  
Time Interval ◽  
Mean Velocity ◽  
Wind Speeds ◽  
Sonic Anemometers ◽  
Order Of Magnitude ◽  
The Times

Abstract. The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300 m meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairs of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50 % reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2 min mean wind speed and 20 min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. However, a vast majority of intervals have no observations in the tower wake, so removing the full 2 or 20 min intervals does not diminish the XPIA dataset.

scholarly journals Identification of Tower Wake Distortions Using Sonic Anemometer and Lidar Measurements

2016 ◽  
Author(s):  
Katherine McCaffrey ◽  
Paul Quelet ◽  
Aditya Choukulkar ◽  
James M. Wilczak ◽  
Daniel E. Wolfe ◽  
...  
Keyword(s):  
Wind Speed ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Sonic Anemometer ◽  
Time Interval ◽  
Mean Velocity ◽  
Wind Speeds ◽  
Sonic Anemometers ◽  
Order Of Magnitude ◽  
The Times

Abstract. The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300-meter meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times, and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairs of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50 % reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2-min mean wind speed and 20-min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. However, a vast majority of intervals have no observations in the tower wake, so removing the full 2- or 20-min intervals does not diminish the XPIA dataset.

The Influence of Wind Direction on Campbell Scientific CSAT3 and Gill R3-50 Sonic Anemometer Measurements

2016 ◽  
Vol 33 (11) ◽  
pp. 2477-2497 ◽  
Author(s):  
Laurent Grare ◽  
Luc Lenain ◽  
W. Kendall Melville
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Friction Velocity ◽  
Sonic Anemometer ◽  
Strongly Correlated ◽  
Sonic Anemometers ◽  
Mean Wind Speed ◽  
The Mean

AbstractMeasurements from the Campbell CSAT3 and Gill R3-50 anemometers were conducted in four different experiments, in laboratory and field environments. Consistent differences between these two sonic anemometers were observed. The data have revealed that the differences were strongly correlated with the wind direction. According to the datasets used, the CSAT3 was the anemometer whose measurements were more sensitive to the instrument’s orientation relative to the wind direction. While the mean wind speed and direction remained within the manufacturers’ specifications (a few percent for the wind speed and a few degrees for the wind direction), the estimates of the friction velocity from the CSAT3 differed from the R3-50 by up to 20%.

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