Wind Measurement Techniques Research Articles

The puzzling north polar region of Uranus: Continued zero-shear winds and increasing brightness from 2015 through 2022 according to 7 years of Keck AO imaging

There may be a permanent north–south asymmetry in the zonal wind profile of Uranus. According to high signal-to-noise near-IR observations with the Keck telescope NIRC2 camera, through 2014 the winds north of 60∘N had a constant (zero shear) longitudinal drift rate of 4.1∘/h westward (Sromovsky et al., 2015). Yet the south polar winds in 1986 had strong latitudinal shear, reaching speeds of 8.5∘/h (Karkoschka, 2015). If that asymmetry were a result of extreme seasonal forcing, it might be expected to reverse before the 2030 solstice. However, continued high signal-to-noise near-IR observations from 2015 through 2022 provide little evidence that the north polar winds have changed at all, although there have been changes in the distribution of cloud features used to track those winds and an increase in the brightness of the background haze that makes it harder to detect these small low-contrast features. Between 2015 and 2017, a gap in easily trackable features developed in the 55∘N–60∘N latitude region, and at the northern edge of that gap there was a hint that a dramatic change to the inverted profile might be starting. To further investigate that possible change and to fill in the gap, we developed a new wind measurement technique that was more sensitive to low-contrast spatial structure. Our new method does not confirm any significant wind speed change in the gap, nor at its northern edge.The lifetimes of many of the small discrete polar features are surprisingly long. Many were tracked over time spans over 24 h, and some lasted for weeks. More prominent features seen at low latitudes seem to persist for multiple years and vary in latitude and drift rate in a cyclical fashion. While measurements so far favor a permanent asymmetry in the zonal wind profile of Uranus, the possibility remains that a dramatic circulation change might take place between 2022 and the next solstice in 2030. Using simplified radiation transfer modeling we infer a largely unchanging upper layer of small particles of very low optical depth vertically distributed above an active deeper mid-level layer, at an effective pressure of ∼2–2.5 bar. That middle layer increased in reflectivity at 1.6 μm by more than a factor of 2 from 2015 to 2022 and is the main source of the top-of-atmosphere brightness increase seen over that period, rather than any significant temporal change in polar methane abundance.

Examining Wind Flow's Impact on Multi-Storey Buildings: A Quest for Quality Improvement

Abstract This scientific article delves into the intricacies of wind flow's impact on multi-storey buildings, presenting results from a series of experimental investigations. The research encompasses an examination of wind interactions with buildings of varying heights and geometric profiles. Furthermore, it unveils the effects of tall structures on the natural ventilation and smoke evacuation systems of shorter edifices, considering different wind flow directions. The study leverages specialized wind tunnel and measurement techniques for a comprehensive analysis of wind-induced loads on buildings. The acquired insights furnish crucial input for the design of single-story temporary modular constructions within densely populated urban areas, subject to wind-induced stresses. Additionally, they hold potential applicability in the advancement of energy-efficient technologies and strategies within the realm of construction. The acquired dataset underscores the criticality of scrutinizing wind flow's impact on structures of varied typologies and dimensions and will allow to significantly improve the quality and efficiency of modern buildings in the future.

Comparing Offshore Ferry Lidar Measurements in the Southern Baltic Sea with ASCAT, FINO2 and WRF

This article highlights the inter-comparisons of the wind measurement techniques available in deep water areas working towards combining them to obtain optimal estimates of the wind power potential. More specifically, this article presents comparisons of the Ferry Lidar Experiment wind data with those of the Advanced Scatterometer (ASCAT), the FINO2 meteorological mast, and the New European Wind Atlas (NEWA) simulations performed using the Weather Research, and Forecasting (WRF) mesoscale model. To be comparable to ASCAT surface winds, which are referenced at 10 m, the ferry lidar and FINO2 wind profile measurements were extrapolated down to 10 m using atmospheric stability information derived from the bulk Richardson number formulation. ASCAT had the lowest associated error compared with that of the ferry lidar in near-neutral atmospheric stratifications, whereas FINO2, despite a distance range of 30 km and a moving ferry lidar target, had the highest correlation and lowest RMSE in all atmospheric conditions. Due to the high frequency of low-level jets caused by the proximity to land from all directions as well as typically stable atmospheric conditions, the extrapolated ferry lidar measurements underpredicted the ASCAT 10 m wind speeds. WRF consistently underperformed compared to the other measurement methods, even with the ability to directly compare results with all other sources at all heights.

Wind Speed Retrieval Method for Shipborne GNSS-R

This study presents a sea surface wind speed retrieval method for the maritime environment, using forward-scattering signals from the global navigation satellite system (GNSS), which benefits from reduced costs compared with active radar detection. Most retrieval algorithms for GNSS-reflectometry (GNSS-R)-based wind measurement technique have predominantly focused on spaceborne and airborne platforms, whereas research related to shipborne platforms is relatively lacking. However, owing to the low altitude of shipborne receiving equipment, the Glistening Zone is concentrated in a small chip range. Therefore, based on the different slopes' change in the front and rear stages of the time-delay waveforms, a threshold wind speed retrieval algorithm was established to improve the retrieval accuracy of shipborne GNSS-R. The experimental results using an actual ship show that the algorithm produces smaller root-mean-square error and mean error, and a maximum deviation of less than 2 m/s.

Single-blind test of airplane-based hyperspectral methane detection via controlled releases

Methane leakage from point sources in the oil and gas industry is a major contributor to global greenhouse gas emissions. The majority of such emissions come from a small fraction of “super-emitting” sources. We evaluate the emission detection and quantification capabilities of Kairos Aerospace’s airplane-based hyperspectral imaging methane emission detection system for methane fluxes of 18–1,025 kg per hour of methane (kgh(CH4)). In blinded controlled releases of methane conducted over 4 days in San Joaquin County, CA, Kairos detected 182 of 200 valid nonzero releases, including all 173 over 15 kgh(CH4) per meter per second (mps) of wind and none of the 12 nonzero releases below 8.3 kgh(CH4)/mps. Nine of the 26 releases in the partial detection range of 5–15 kgh(CH4)/mps were detected. There were no false positives: Kairos did not detect methane during any of the 21 negative controls. Plume quantification accuracy depends on the wind measurement technique, with a parity slope of 1.15 (σ = 0.037, R2 = 0.84, N = 185) using a cup-based wind meter and 1.45 (σ = 0.059, R2 = 0.80, N = 157) using an ultrasonic anemometer. Performance is comparable even with only modeled wind data. For emissions above 15 kgh/mps, quantification error scales as roughly 30%–40% of emission size, even when using wind reanalysis data instead of ground-based measurements. This reflects both uncertainty in wind measurements and in Kairos’ estimates. These findings suggest that at 2 mps winds under favorable environmental conditions in the United States, Kairos could detect and quantify over 50% of total emissions by identifying super-emitting sources.

Wind Measurement and Simulation Techniques in Multi-Rotor Small Unmanned Aerial Vehicles

Wind disturbance presents a formidable challenge to the flight performance of multi-rotor small unmanned aerial vehicles (sUAVs). This paper presents a comprehensive review of techniques for measuring wind speed and airspeed for multi-rotor sUAVs. Three categories of sensing techniques are reviewed: flow sensors, anemometers, and tilt-angle based approaches. We also review techniques for generating wind disturbances in simulation. Wind simulation techniques that use power spectral density (PSD) functions, computational fluid dynamics (CFD), and probabilistic models are examined. Finally, we provide an open-source Python implementation of the Dryden wind turbulence model and embedded code to interface with an ultrasonic anemometer.

Development of Direct-Detection Doppler Wind Lidar for Vertical Atmospheric Motion

Wind is fundamental in many atmospheric phenomena. Global wind profile observation is important to improve numerical weather prediction (NWP) and various meteorological studies. Wind profile observations are measured mainly by radiosonde networks. A Doppler Wind Lidar (DWL) is a useful remote sensing technique for wind measurement. DWL would provide us with a wind profile having high vertical resolution, low bias, and good precision. The National Institute of Information and Communications Technology (NICT) studies DWL has been developing various DWL. In the paper, we report development of a 355-nm direct-detection DWL and describe recent results of a 2-µm coherent DWL at NICT.

A semi-empirical model for mean wind velocity profile of landfalling hurricane boundary layers

The existence of the super-gradient-wind region, where the tangential winds are larger than the gradient wind, has been widely observed inside the hurricane boundary layer. Hence, the extensively used log-law or power-law wind profiles under near-neutral conditions may be inappropriate to characterize the boundary layer winds associated with hurricanes. Recent development in the wind measurement techniques overland together with the abundance of data over ocean enabled a further investigation on the boundary layer wind structure of hurricanes before/after landfall. In this study, a semi-empirical model for mean wind velocity profile of landfalling hurricanes has been developed based on the data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network operated by the National Weather Service and the Global Positioning System (GPS) dropsondes collected by the National Hurricane Center and Hurricane Research Division. The proposed mathematical representation of engineering wind profile consists of a logarithmic function of the height z normalized by surface roughness z0 (z/z0) and an empirical function of z normalized by the height of maximum wind δ (z/δ). In addition, the consideration of wind direction in terms of the inflow angle is integrated in the boundary layer wind profile. Field-measurement wind data for both overland and over-ocean conditions have been employed to demonstrate the accuracy of simulation and convenience in use of the developed semi-empirical model for mean wind velocity profile of landfalling hurricanes.

Review of recent experimental studies of the shock train flow field in the isolator

Since the concept of hypersonic flight was proposed, progress of the related theory, experiments and simulations has been gained. As an important component of the scramjet engine, the isolator plays a key role in the engine performance and flight success. The flow mechanism it involves is very complicated. In the view point of experimental research, this paper reviews the recent progress of scramjet isolator studies, analyzes the features of the isolator flow based on fine flow diagnosis technique (nano-tracer planar laser scattering, NPLS), including the three-dimensional structures of the shock train flow field, turbulent characteristics, hysteresis motions, unstart flow and shock train leading edge detection. Studies of the isolator flow can be classified and discussed according to the wind tunnel facility, isolator design and measurement techniques. Based on this, suggestions for further research can be proposed.

Rotor equivalent wind speed for power curve measurement – comparative exercise for IEA Wind Annex 32

A comparative exercise has been organised within the International Energy Agency (IEA) Wind Annex 32 in order to test the Rotor Equivalent Wind Speed (REWS) method under various conditions of wind shear and measurement techniques. Eight organisations from five countries participated in the exercise. Each member of the group has derived both the power curve based on the wind speed at hub height and the power curve based on the REWS. This yielded results for different wind turbines, located in diverse types of terrain and where the wind speed profile was measured with different instruments (mast or various lidars). The participants carried out two preliminary steps in order to reach consensus on how to implement the REWS method. First, they all derived the REWS for one 10 minute wind speed profile. Secondly, they all derived the power curves for one dataset. The main point requiring consensus was the definition of the segment area used as weighting for the wind speeds measured at the various heights in the calculation of the REWS. This comparative exercise showed that the REWS method results in a significant difference compared to the standard method using the wind speed at hub height in conditions with large shear and low turbulence intensity.

A4 パラフォイル飛行中の簡易風計測法について(宇宙輸送・飛翔体)

A4 パラフォイル飛行中の簡易風計測法について(宇宙輸送・飛翔体)

Mobile Rayleigh Doppler wind lidar based on double-edge technique

We describe a mobile molecular Doppler wind lidar (DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km. A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity. The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing. To guarantee wind accuracy, a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon. The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s. The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar (WPR). Evaluation is achieved by comparing at altitudes from 2 to 8 km. The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges. The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.

Reply to comment by R. Dhanya and S. Gurubaran on “Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system”

Reply to comment by R. Dhanya and S. Gurubaran on “Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system”

Evaluation of DBS Wind Measurement Technique in Different Beam Configurations for a VHF Wind Profiler

Abstract Atmospheric winds in the troposphere have been observed routinely for many years with wind profiling (VHF and UHF) radars using the Doppler beam swinging (DBS) technique. Accuracy of wind estimates using wind profiling radars with different beam configurations has its limitations due to both the system of observation and atmospheric conditions. This paper presents a quantitative analysis and evaluation of horizontal wind estimation in different beam configurations up to an altitude of 18 km using the mesosphere–stratosphere–troposphere (MST) radar located in Gadanki, India. Horizontal wind velocities are derived in three different ways using two-, three-, and four-beam configurations. To know the performance of each configuration, radar-derived winds have been compared with the winds obtained by simultaneous GPS sonde balloon measurements, which are considered to be a standard reference by default. Results show that horizontal winds measured using three different beam configurations are comparable in general but discrepancy varies from one beam configuration to the other. It is observed that horizontal winds measured using four-beam configuration (east, west, north, and south) have better estimates than the other two-beam configurations. The standard deviation was found to be varying from 1.4 to 2.5 m s−1 and percentage error is about 9.68%–12.73% in four-beam configuration, whereas in other beam configurations the standard deviation is about 1.65–3.9 m s−1 and the percentage error is about 11.29%–15.16% with reference to GPS sonde balloon–measured winds.

Evaluation of Three-Beam and Four-Beam Profiler Wind Measurement Techniques Using a Five-Beam Wind Profiler and Collocated Meteorological Tower

Abstract In this paper a five-beam wind profiler and a collocated meteorological tower are used to estimate the accuracy of four-beam and three-beam wind profiler techniques in measuring horizontal components of the wind. In the traditional three-beam technique, the horizontal components of wind are derived from two orthogonal oblique beams and the vertical beam. In the less used four-beam method, the horizontal winds are found from the radial velocities measured with two orthogonal sets of opposing coplanar beams. In this paper the observations derived from the two wind profiler techniques are compared with the tower measurements using data averaged over 30 min. Results show that, while the winds measured using both methods are in overall agreement with the tower measurements, some of the horizontal components of the three-beam-derived winds are clearly spurious when compared with the tower-measured winds or the winds derived from the four oblique beams. These outliers are partially responsible for a larger 30-min, three-beam standard deviation of the profiler/tower wind speed differences (2.2 m s−1), as opposed to that from the four-beam method (1.2 m s−1). It was also found that many of these outliers were associated with periods of transition between clear air and rain, suggesting that the three-beam technique is more sensitive to small-scale variability in the vertical Doppler velocity because of its reliance on the point measurement from the vertical beam, while the four-beam method is surprisingly robust. Even after the removal of the rain data, the standard deviation of the wind speed error from the three-beam method (1.5 m s−1) is still much larger than that from the four-beam method. Taken together, these results suggest that the spatial variability of the vertical airflow in nonrainy periods or hydrometeor fall velocities in rainy periods makes the vertical beam velocities significantly less representative over the area across the three beams, and decreases the precision of the three-beam method. It is concluded that profilers utilizing the four-beam wind profiler technique have better reliability than wind profilers that rely on the three-beam wind profiler technique.

Comparison of offshore wind park sites using SAR wind measurement techniques

AbstractWind farming has grown rapidly in Europe over the last decade. All European countries with shallow coastal waters and strong mean coastal wind speeds are planning or already constructing offshore wind farms. Large parts of the North Sea and Baltic Sea are being investigated to see whether they are suitable for offshore wind parks. In this study we show how satellite images taken by space‐borne radar sensors can be used to determine mesoscale wind fields and thus help in the task of planning offshore wind farms. High‐resolution synthetic aperture radar (SAR) images acquired by the European remote sensing satellite ERS‐2 showing single wind turbines are investigated. The methods for retrieving high‐resolution wind fields from SAR images are explained and statistical comparisons of wind speed and wind direction at the two offshore wind park sites in the North Sea, Horns Rev and Butendiek, are given. Copyright © 2005 Royal Meteorological Society

Aeroacoustic Measurements

9R7. Aeroacoustic Measurements. - Edited by TJ Mueller (Dept of Aero and Mech Eng, Univ of Notre Dame, 112 Hessert Center, Notre Dame IN 46556-5684). Springer-Verlag, Berlin. 2002. 313 pp. ISBN 3-540-41757-5. $99.00.Reviewed by MG Prasad (Dept of Mech Eng, Stevens Inst of Tech, Hoboken NJ 07030).It is well known that experimental work plays an important role in acoustics. In particular, the acoustical measurements in the presence of airflow is challenging due to test conditions. This book deals with this challenging and important topic in acoustics namely aeroacoustics. The five chapters of the book deal with various aspects aeroacoustic measurements with applications. Chapter 1, on “Microphone measurements in and out of air stream,” deals with the acoustic characteristics of wind tunnels. The discussions include criteria for simulation of aeroacoustic test environment with requirements such as propagation effect, scaling, low background noise levels, etc. Chapter 2 presents “Beam forming in acoustic testing.” The use of beam forming technique and its applications in the modeling of wind tunnel noise with non-acoustic hard walls and free jets are discussed. Several beam forming algorithms with techniques for removing interference is discussed in this chapter. Chapter 3 covers “Aeroacoustic phased array testing in low speed wind tunnels.” A comprehensive treatment of the design and application of acoustic phased array measurement capability for low speed wind tunnels is presented. Various aspects of operation such as calibration, data handling, etc, are discussed. Chapter 4 is on “Source characterization by correlation techniques.” The characterization of acoustical sources using correlation techniques is presented. The chapter discusses various mathematical aspects through cross-correlation and coherence functions. Various examples including correlation measurements between surface pressure and far field acoustic pressure field data are included. The last chapter is “An anechoic facility for basic aeroacoustic research.” The chapter presents the design, construction, and performance evaluation of an anechoic wind tunnel facility for low speed and low turbulence applications. Use of such a facility to experimentally investigate fluid-solid interaction is discussed. A specific wind tunnel facility is described. As an example the use of the facility for a marine propeller response to inflow disturbance is discussed. All chapters are well presented. In summary, Aeroacoustic Measurements is a nice integration of presentations of various recognized contributors. The book deals with important issues in design and performance evaluation of wind tunnel test facilities, measurement techniques, and mathematical aspects. Nice photographs and figures are included. Each chapter has a large number of references. The book is recommended for libraries and all graduate students, researchers, and professionals in acoustics. In particular, those involved in experimental aeroacoustics will find this book very useful.

Using ADCP Background Sound Levels to Estimate Wind Speed

Abstract It is well known that ambient sound is generated by wind through the process of wave breaking and bubble injection. The resulting sound levels are highly correlated with wind speed and, even though the physical process is not fully understood, sound levels can be used to estimate wind speeds with accuracies comparable to other marine wind measurement techniques. It has been noted by several researchers that background sound levels in acoustic Doppler current profiler (ADCP) systems are correlated to wind speeds; however, conventional wisdom would suggest that this signal should be dominated by thermal noise. In this report, background sound levels in 75-, 150-, and 300-kHz ADCP systems have been investigated. Techniques required to convert raw data into absolute sound levels and to adjust these values to estimate representative surface sound levels are presented. Only the background sound levels in the 150-kHz ADCP retain a signal from the surface-generated ambient sound. For these systems, deplo...

Clear air boundary layer spaced antenna wind measurement with the Multiple Antenna Profiler (MAPR)

Abstract. Spaced antenna (SA) wind measurement techniques are applied to Multiple Antenna Profiler (MAPR) data to evaluate its performance in clear air conditions. MAPR is a multiple antenna 915 MHz wind profiler developed at the National Center for Atmospheric Research (NCAR) and described in Cohn et al. (1997), designed to make high resolution wind measurements. Previous reported measurements with MAPR were restricted to precipitation because of low signal to noise (SNR) and signal to ground-clutter (SCR) ratios. By using a standard pulse-coding technique and upgrading the profiler control software, increases in average power and SNR were achieved, making routine measurements in clear air possible. Comparison of winds measured by MAPR and by a sonic anemometer on a nearby 300 m tower show correlation coefficients in the range of R2 = 0.75 – 0.80, and an average absolute error of ~ 1.4 m s - 1 . This compares favorably with the agreement typically found in wind profiler comparisons. We also consider the use of the parameter ah , which is related to the value of the cross-correlation function at its zero crossing. This parameter is a data quality indicator and possibly a key component in a ground clutter removal technique.Key words. Meteorology and atmospheric dynamics (mesoscale meteorology; instruments and techniques) – Radio science (remote sensing)

Comment on “Theory of the double-edge molecular technique for Doppler lidar wind measurement”

A theory of the double-edge technique for lidar measurement of wind speed Doppler shifts was recently presented by Flesia and Korb [Appl. Opt. 38, 432 (1999)]. It is shown here that the technique proposed by Flesia and Korb to achieve equal responsivity to aerosol and Rayleigh backscatter signals was previously conceived and demonstrated by another group.