Retrieving wind statistics from average spectrum of continuous-wave lidar

Abstract. The aim of this study is to experimentally demonstrate that the time-average Doppler spectrum of a continuous-wave lidar is proportional to the probability density function of the line-of-sight velocities. This would open the possibility of using cw lidars for a precise determination of the second-order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems.

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Retrieving wind statistics from average spectrum of continuous-wave lidar

Atmospheric Measurement Techniques ◽

10.5194/amt-6-1673-2013 ◽

2013 ◽

Vol 6 (7) ◽

pp. 1673-1683 ◽

Cited By ~ 23

Author(s):

E. Branlard ◽

A. T. Pedersen ◽

J. Mann ◽

N. Angelou ◽

A. Fischer ◽

...

Keyword(s):

Continuous Wave ◽

Doppler Spectrum ◽

Line Of Sight ◽

Spatial Averaging ◽

Turbulence Statistics ◽

Average Spectrum ◽

Sonic Anemometers ◽

Time Average ◽

Wind Statistics

Abstract. The aim of this study is to experimentally demonstrate that the time-average Doppler spectrum of a continuous-wave (cw) lidar is proportional to the probability density function of the line-of-sight velocities. This would open the possibility of using cw lidars for the determination of the second-order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems.

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Toward Non-Invasive Measurement of Atmospheric Temperature Using Vibro-Rotational Raman Spectra of Diatomic Gases

Remote Sensing ◽

10.3390/rs12244129 ◽

2020 ◽

Vol 12 (24) ◽

pp. 4129

Author(s):

Tyler Capek ◽

Jacek Borysow ◽

Claudio Mazzoleni ◽

Massimo Moraldi

Keyword(s):

Continuous Wave ◽

Molecular Nitrogen ◽

Atmospheric Temperature ◽

Precise Determination ◽

Gas Temperature ◽

Advantages And Disadvantages ◽

Non Invasive ◽

Potential Applications ◽

532 Nm

We demonstrate precise determination of atmospheric temperature using vibro-rotational Raman (VRR) spectra of molecular nitrogen and oxygen in the range of 292–293 K. We used a continuous wave fiber laser operating at 10 W near 532 nm as an excitation source in conjunction with a multi-pass cell. First, we show that the approximation that nitrogen and oxygen molecules behave like rigid rotors leads to erroneous derivations of temperature values from VRR spectra. Then, we account for molecular non-rigidity and compare four different methods for the determination of air temperature. Each method requires no temperature calibration. The first method involves fitting the intensity of individual lines within the same branch to their respective transition energies. We also infer temperature by taking ratios of two isolated VRR lines; first from two lines of the same branch, and then one line from the S-branch and one from the O-branch. Finally, we take ratios of groups of lines. Comparing these methods, we found that a precision up to 0.1 K is possible. In the case of O2, a comparison between the different methods show that the inferred temperature was self-consistent to within 1 K. The temperature inferred from N2 differed by as much as 3 K depending on which VRR branch was used. Here we discuss the advantages and disadvantages of each method. Our methods can be extended to the development of instrumentation capable of non-invasive monitoring of gas temperature with broad potential applications, for example, in laboratory, ground-based, or airborne remote sensing.

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

Atmospheric Measurement Techniques ◽

10.5194/amt-11-6339-2018 ◽

2018 ◽

Vol 11 (11) ◽

pp. 6339-6350 ◽

Cited By ~ 3

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.

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Comparison of Methods to Derive Radial Wind Speed from a Continuous-Wave Coherent Lidar Doppler Spectrum

10.5194/amt-2018-229 ◽

2018 ◽

Author(s):

Dominique P. Held ◽

Jakob Mann

Keyword(s):

Wind Speed ◽

Continuous Wave ◽

Transfer Functions ◽

Sonic Anemometer ◽

Volume Averaging ◽

Doppler Spectrum ◽

High Temporal Resolution ◽

Centroid Method ◽

Sonic Anemometers ◽

Maximum Method

Abstract. Continuous-wave lidar systems offer the possibility to remotely sense wind speed but are also affected by inherent 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 (RMSE) between a lidar and a sonic anemometer. Numerical simulations and experimental results both indicate that the maximum method, even though using the least amount of information from the Doppler spectrum, performs best at mitigating the volume averaging effect. However, this benefit is paid by increased signal noise due to the discretisation of the maximum method. The median method shows slight improvements over the centroid method in terms of volume averaging reduction and also resulted in the overall lowest RMSE. Thus, when the aim is to obtain point-like wind speed time series with high temporal resolution, the median method is superior to the centroid and maximum method. When comparing 10 minute averages there is no difference between the methods.

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NOESY around the critical point Omega Tau c = 1.12. Precise determination of proton-proton distances and reorientation correlation times with two-field NOESY

Molecular Physics ◽

10.1080/002689700162621 ◽

2000 ◽

Vol 98 (4) ◽

pp. 201-210

Author(s):

Tao Zhang, Xi-An Mao, Matthias Baur, Ho

Keyword(s):

Critical Point ◽

Precise Determination ◽

Correlation Times ◽

Proton Proton

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Precise determination of 14 REEs in GSJ/AIST geochemical reference materials JCp-1 (coral) and JCt-1 (giant clam) using isotope dilution ICP-quadrupole mass spectrometry

GEOCHEMICAL JOURNAL ◽

10.2343/geochemj.2.0498 ◽

2018 ◽

Vol 52 (1) ◽

pp. 75-79 ◽

Cited By ~ 2

Author(s):

Tsuyoshi Tanaka ◽

Seung-Gu Lee ◽

Taehoon Kim ◽

Seunghee Han ◽

Hyo Min Lee ◽

...

Keyword(s):

Mass Spectrometry ◽

Reference Materials ◽

Isotope Dilution ◽

Precise Determination ◽

Giant Clam ◽

Quadrupole Mass ◽

Quadrupole Mass Spectrometry ◽

Geochemical Reference Materials

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PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

ACTA METALLURGICA SINICA ◽

10.3724/sp.j.1037.2010.00411 ◽

2010 ◽

Vol 46 (4) ◽

pp. 411-417 ◽

Cited By ~ 4

Author(s):

Yang MENG ◽

Lin GU ◽

Wenzheng ZHANG

Keyword(s):

Precise Determination ◽

Interface Orientation

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Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

Silva Gandavensis ◽

10.21825/sg.v12i0.1009 ◽

1968 ◽

Vol 12 ◽

Author(s):

R. Goossens

Keyword(s):

Basal Area ◽

Precise Determination ◽

Maximum Diameter ◽

Precise Method ◽

Maximum Radius ◽

The Core ◽

Two Parameters

A precise method for the determination of the increment of the basal area using the PressIer bore. Refering to previous research showing that the basal area of the corsica pine could be characterized by an ellips, we present in this paper a precise method for the determination of the increment of the basal area. In this method we determine the direction of the maximum diameter, we measure this diameter and we take a core in one of the points of tangency of the caliper with the measured tree. The determination of the diameter perpendicular to the maximum diameter finishes the work wich is to be done in the forest. From the classical measurements effectuated on the core and from the measured diameters we can then determine the form (V) and the excentricity (e). Substituting these two parameters in the formula 2 or 2', we can also calculate the error of a radius measured on the core with respect to the representative radius, This error with them allow us to correct the measured value of the minimum or the maximum radius and we will be able to do a precise determination of the increment.

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