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Below is a selection of our brochures, technical papers and reports for your convenience.

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Turning the Tides on Wind Measurements: The Use of Lidar to Verify the Performance of a Meteorological Mast
M Smith, S Wylie, A Woodward and M Harris (2017)
This work outlines, through a number of case studies, a cost-effective approach for verifying the performance of a met mast using a continuous wave lidar, ZephIR 300, ensuring that calibration of the data is both accurate and problem-free. Once deployed for mast verification, ZephIR 300 also provides the ability to validate the wind shear model used for a particular deployment, demonstrating a further reduction in the uncertainty associated with the extrapolation of mast data within the wind resource campaign.

The use of Computational Fluid Dynamics to Post-Process ZephIR 300 Wind Speed Data in Complex Terrain
S Wylie, A Woodward, S Sanquer, C Vezza (2017)
In this work, CFD conversion of measurements taken by a Continuous Wave lidar, ZephIR 300, in varying terrain types and complexity is demonstrated, highlighting a transparent methodology that is capable of producing bankable measurements in terrain not considered to be simple.

Repeatability of ZephIR performance demonstrated across sample of 240 IEC compliant ZephIR 300 performance verifications
M Mangat (2016)
This report presents the updated results from over 240 ZephIR 300s validated against a tall IEC compliant meteorological mast. Since 2010, ZephIR have operated the first UK remote sensing test site. With the increasing number of ZephIR 300s being validated against this mast, statistical analysis of validation results robustly shows the repeatability and stability of the calibration of ZephIR 300s.

Validation of measurements from a ZephIR Lidar
P Argyle & S Watson, EWEA (2015)

A large dataset from a ZephIR 300 has been independently analysed by a team from Loughborough University. The performance has been assessed in comparison to a 91m met mast; wind speed, direction, TI and atmospheric stability have all been examined, and the conclusion is that the lidar is capable of measuring the wind resource to at least the same standard as a met mast.

Derivation of cup-equivalent turbulence from Doppler spectra obtained by scanning CW lidar
M Pitter et al, EWEA (2015)
The paper examines the potential for CW lidar to measure turbulence characteristics from both ground-based and turbine-mounted lidar. A new method has been applied for the second of these cases, in which the instantaneous Doppler spectrum is used to derive a value of turbulence that corresponds closely to that measured by a cup. In doing so it avoids some of the well-known difficulties caused by spatial averaging and contamination by vertical components.

Can the wind industry bank on wind lidar?
Windpower Monthly (2014)
Can you use wind lidar to provide quantitative data for the annual energy prediction (P50, P75 and P90) of a modern scale wind farm, allowing developers to raise the necessary finance to progress and construct full-scale developments? This paper demonstrates ZephIR’s acceptance across onshore benign sites, onshore complex sites, offshore on fixed platforms and offshore on floating platforms.

Performance stability of ZephIR in high motion environments: Floating and turbine mounted
M Pitter et al (2014)
This paper demonstrates by simulations, controlled experimental studies and the results of field deployments that the effect of motion on ZephIR performance is insignificant and easily compensated, largely due to the high-resolution, fast data rates and multiple viewing angles enabled by the very high carrier to noise ratio unique to continuous wave wind lidars, such as ZephIR. Stability of ZephIR performance is therefore confirmed for cases where lidar is subject to extreme motion, namely mounted on a floating offshore platform or on a wind turbine nacelle.

Classification of ZephIR 300 Lidar at the UK Remote Sensor Test Site
J Medley (2014)
Two ground-based ZephIR 300 lidars have been classified at the UK Remote Sensor Test Site at Pershore according to the procedure described in Annex L of the IEC draft guidelines. The mean accuracy classes for these units cover the ranges 3.0% – 3.8% for heights between 20 m and 91 m, after accounting for correlations between the environmental parameters. These values correspond to mean standard uncertainties of 1.7% – 2.2%.

ZephIR sensitivity in clear air, low temperatures and high altitudes
E Burin des Roziers (2014)
The increasing number of ZephIR deployments in more extreme environments demonstrate ZephIR 300’s ability to retain high availability (>90%) in very cold conditions and in extremely clear atmospheres. This report covers the theoretical limits of CW lidar sensitivity with range, and aerosol concentration and presents results from a long (>12 months) continuous ZephIR 300 campaign at high latitude exhibiting extremes in temperature and air clarity.

Repeatability of ZephIR performance demonstrated across sample of 170 IEC compliant ZephIR 300 performance verifications
E Burin des Roziers (2014)
This report presents the results from over 170 ZephIR 300s validated against a tall IEC compliant meteorological mast. Since 2010, ZephIR have operated the first UK remote sensing test site. With the increasing number of ZephIR 300s being validated against this mast, statistical analysis of validation results robustly shows the repeatability and stability of the calibration of ZephIR 300s.

ZephIR performance evaluation after 40 months of continual operation
M M A Mangat (2014)
This report demonstrates the performance of a ZephIR Continuous Wave (CW) lidar over a period of 40 months continual operation. It examines the performance before and after the 40 month operational deployment, during which time no maintenance or servicing has been conducted on the ZephIR.

Project Cyclops: the way forward in power curve measurements?
S Feeney et al, EWEA (2014)
A ZephIR DM lidar was mounted on the nacelle of a large turbine, adjacent to a fixed mast and a second ground-based vertically profiling ZephIR DM. The wind speed and turbine power curve measurements from both ZDM lidars were in very close agreement with each other and with the reference mast, showing very little bias or scatter.

The impact of tilt and inflow angle on ground-based lidar wind measurements
M Mangat et al, EWEA (2014)
An investigation of ground-based ZephIR 300 units at the Pershore test site shows that the horizontal wind speed is negligibly affected by a static tilt of the lidar up to 10 degrees. The data are also used to demonstrate the accurate measurement of inflow angle by ZephIR 300.

Evaluation of wind flow with a nacelle-mounted continuous wave wind lidar
J Medley et al, EWEA (2014)
Measurements by a ZephIR DM lidar mounted on the nacelle of a test turbine at Riso DTU have been validated against a met mast, and have been used to derive a rotor-equivalent power curve in accordance with the latest draft of the IEC guidelines.

Correlation effects in the field classification of ground-based remote wind sensors
W Barker et al, EWEA (2014)
Analysis has been carried out on data from ZephIR 300 units deployed at the Pershore test site, in accordance with the classification scheme for remote sensing devices proposed in the latest IEC guidelines.

Lidar turbulence measurements for wind turbine selection studies: design turbulence
W Barker et al, EWEA (2014)
A major use of turbulence data in a site assessment campaign is to inform the selection of wind turbine type. Analysis of turbulence data from ground-based ZephIR 300 units has been used to investigate a hypothetical wind farm layout; the overall choice of turbine type is unaffected by whether lidar or mast data is used.

Finance grade wind measurements with lidar
W, Barker et al, EWEA (2014)
Lidar can offer significant financial savings in comparison to traditional methods of anemometry for resource assessment, partly through reduction of uncertainty.

ZephIR Dual Mode
WindTech International (2013)
March 2013 saw the tenth anniversary of the first commercial lidar deployment for wind energy applications – and while it is now commonplace to see wind lidars (such as ZephIR 300 and those that followed) in wind energy resource assessments, it was actually a turbine-mounted application for which the ZephIR technology was first deployed.

Relative power curve measurements using turbine-mounted, continuous-wave lidar
C Slinger et al, EWEA (2013)
Nacelle-mounted lidar offers an exciting alternative to conventional methods for measurement of turbine power curves.

Lidar turbulence measurements for wind farm energy yield analysis
W Barker et al, EWEA (2013)
Measurement of turbulence intensity (TI) at hub height plays a role in wind resource assessment through the estimation of energy losses due to turbine wakes and is also a key component of site classification and turbine selection studies.

The effect of motion on continuous wave lidar wind measurements
A Rutherford et al, AWEA (2013)
The results in this paper demonstrate that the exceptional sensitivity and high data rates of CW wind lidars allows high quality wind measurement to be carried out in many buoy-mounted applications without motion compensation.

Lidar calibration and performance validation process
T Rutherford et al, AWEA (2012)
This paper describes recent advances in the calibration and performance verification of ZephIR 300 lidar units.

Lidar and computational fluid dynamics for resource assessment in complex terrain
M Pitter et al, EWEA (2012)
This paper contains a description of a complex flow conversion technique that converts raw lidar line-of-sight velocity data into precise, unbiased measurements of horizontal wind speed on hilly and mountainous sites.

Can lidars measure turbulence? Comparison between ZephIR 300 and an IEC-compliant anemometer mast
W Barker et al, EWEA (2012)
Results are presented of a comparison of TI measurements from several ZephIR 300 units against an IEC compliant 91.5m anemometer mast. The data were collected over more than 5000 hours of operation at Natural Power’s dedicated lidar and sodar test site.

Demonstration of short-range wind lidar in a high-performance wind tunnel
A T Pedersen et al, EWEA (2012)
A modified ZephIR unit has provided the first successful demonstration of lidar in a wind tunnel. Very good correlation with reference measurements was obtained across the full speed range of 5-75 m/s.

ZephIR #301 Independent Evaluation Test by Riso DTU
Angelou, N. and Mikkelsen, T. (May 2011)
Risø DTU has carried out an evaluation test of the new ZephIR 300 (Z300) wind lidar over a 5 week period in 2011. The full report and data summary is available.

Introducing the New ZephIR 300
Locker, I. and Woodward, A. (2010)
In 2005 ZephIR, the first wind lidar system for the wind industry, became commercially available founded on decades of lidar expertise within QinetiQ, a UK research and development laboratory.

Validated adjustment of remote sensing bias in complex terrain using CFD
Harris, M., Locker, I., Douglas, N., Girault, R., Abiven, C., Brady, O. (2010)
The horizontal wind speed measured lidar can be subject to differences in comparison to that measured by cup anemometers when flow is non-uniform across the lidar measurement disk.

Comparison of ZephIR Measurement Against Cup Anemometry and Power Curve Assessment
Cayla, M. (2010)
This paper reports the results of a measurement campaign in which wind turbine power curves have been evaluated using a ZephIR laser anemometer. The study was carried out in collaboration with EDF Energies Nouvelles.

ZephIR 145 Validation Test
Courtney, M. & Gottschall, J. Risoe DTU report (2010)
Risø DTU carried out a validation test of ZephIR lidar 145 in the period 22 Oct to 17 November 2009. The lidar was placed 40m north of the meteorological tower at Høvsøre Test Station for Large Wind Turbines, Denmark.

Performance of ZephIR at upper heights against a 200m mast at Mason City, Iowa
Barker, W. (2009)
This report presents the post processing and analysis of data sets from a ZephIR laser anemometer and an anemometer mast equipped with cup and vane instruments co-located in Mason City, Iowa.

Investigation of turbulence measurements with a continuous-wave conically scanning lidar
Wagner, R. Mikkelsen, T & Courtney, M, Risoe-R-1682(EN) (2009)
It has been shown many times that the mean horizontal wind speed measured by a lidar over flat terrain compares very well with that measured by a cup anemometer. But can a lidar measure turbulence? This report investigates the case of a continuous wave, conically scanning Zephir lidar.

Exploring lidar remote sensing technology for offshore wind resource monitoring applications
Jaynes, D. & Jacquemin, J. GL Garrad Hassan (2009)
Offshore wind farm projects that require pre-construction financing cannot afford to rely on proxy data that are recorded at distant locations to characterize key design parameters present at the proposed site.

ZephIR wind resource measurement by laser anemometry
WindTech International (2007)
Laser anemometry was first developed in the 1970s using gas lasers, and until recently has been used primarily as a research tool. The ZephIR laser anemometer can be rapidly deployed, configured and redeployed, with both on-board data storage and wireless data transmission.

ZephIR Lidar assessment at the offshore met mast on platform
Kindler, D. WINDTEST, 2006. Report No WT 5256/06. FINO-1. s.l
In February 2006 WINDTEST Kaiser-Wilhelm-Koog GmbH (WINDTEST) was ordered by TALISMAN ENERGY (Limited) UK to assess the offshore performance of a LiDAR system of type QinetiQ/ZephIR relative to classical measurements at an offshore meteorological mast on the German wind energy research platform FINO-1 located in the German North Sea sector.

Additional papers

Full-scale field test of a blade-integrated dual-telescope wind lidar
A T Pedersen et al, EWEA (2013)
The paper describes the first investigation in which lidar units are installed in the blades of a large wind turbine. The data showed potential for real-time evaluation of angle of attack, and the impact of shear was observed as the blade traces out the rotor disc.

Full two-dimensional rotor plane inflow measurements by a spinner-integrated wind lidar
M Sjöholm et al, EWEA (2013)
A modified ZephIR lidar was mounted in the spinner of a large turbine and incorporating a novel two-dimensional scanner. The data provide unprecedented detail of the incoming flow pattern, allowing investigation of phenomena such as wakes and natural turbulence.

Lidar wind speed measurements from a rotating spinner: “SpinnerEx 2009”
N Angelou et al, Riso Report (2010) Riso-R-1741(EN)
The feasibility of upwind observations via a spinner-mounted wind lidar was demonstrated for the first time during this experiment. A ZephIR lidar was installed in the rotating spinner of a MW-sized turbine for several months during 2009.

Light detection and ranging measurements of wake dynamics
Part I: F Bingol et al, Wind Energy 13 51-61 (2010)
Part II: J-J Trujillo et al, Wind Energy 14 61-75 (2011)
The experiment was conducted with a modified ZephIR to test the simple hypothesis that the wake deficit is advected passively by the larger-than-rotor-size eddies in the atmospheric flow, and that the wake at the same time widens gradually, primarily because of mixing caused by small-scale atmospheric eddies.

Flow tilt angles near forest edges – Part 2: lidar anemometry
E Dellwik et al, Biogeosciences 7 1759-1768 (2010)
The paper used a ZephIR for several studies and reaches a conclusion that lidar anemometry can provide consistent estimates of mean flow tilt angles also for the very turbulent forest flow. In general, the results from all sites pointed to the high accuracy of the lidar.

Conically scanning lidar error in complex terrain
F Bingol et al, Met Zeitschrift, 18 189-196 (2009)
WAsP Engineering was used to provide a correction to ZephIR lidar data obtained in complex terrain that accounts for the non-uniform flow across the scan disk.

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