Ground-based Rayleigh laser radar wind speed measurement uncertainty GUM evaluation method

Abstract

The invention discloses a GUM evaluation method for wind speed measurement uncertainty of a ground-based Rayleigh laser radar, and the method comprises the steps: determining a measurement uncertainty source after a wind speed measurement model and main parameters of the ground-based Rayleigh laser radar are determined; the uncertainty sources comprise detection channel photon noise, reference channel photon noise, detection channel background noise, reference channel background noise, detection channel dead zone time, reference channel dead zone time and reference wavelength, and respectively calculating the measurement uncertainty and sensitivity coefficient introduced by the uncertainty sources; and obtaining the measurement uncertainty component of each uncertainty source, and finally synthesizing the wind speed standard measurement uncertainty. The complete wind speed measurement uncertainty evaluation method provided by the invention can accurately and efficiently evaluate the wind speed measurement uncertainty of the ground-based Rayleigh laser radar during high-altitude detection.

Description

Technical Field

[0001] The invention belongs to the field of measurement testing and environmental detection, and in particular relates to a method for evaluating the uncertainty of wind speed measurement. Background Art

[0002] With the increasing demand for high-altitude atmospheric environment cognition and assessment of the dispersion of detection data in the defense field, uncertainty assessment of detection data has become a crucial link. Measurement uncertainty can characterize the dispersion and credibility of measurement results, and indirectly reflect the quality of detection activities. Ground-based Rayleigh LiDAR can detect atmospheric wind speed, wind speed, wind field and other environmental parameters at an altitude of 30km to 80km from the ground. It is an important detection method for near-space environment cognition. Therefore, the assessment of its measurement uncertainty is particularly important for the quality control of data and detection activities. The GUM measurement uncertainty assessment method is relatively simple to calculate, and it is easy to use software calculations for batch data, but there are certain subjective factors, and the sensitivity coefficient is very difficult to solve.

[0003] The main technical difficulties include the following three items:

[0004] Prior to the invention of this patent, there was no effective method for evaluating the uncertainty of ground-based lidar wind speed measurements, and there was insufficient understanding of the dispersion of measurement results.

[0005] The ground-based Rayleigh LiDAR detection system has complex composition and numerous equipment parameters, which poses great difficulties for digital twins. It is difficult to assess measurement uncertainty with only a few basic parameters.

[0006] Since the sensitivity coefficient contains many partial derivatives of composite functions, it needs to be obtained through approximate calculation and derivation, which makes the evaluation calculation more difficult. Summary of the invention

[0007] The purpose of the present invention is to provide a complete wind speed measurement uncertainty assessment method, which can accurately and efficiently assess the wind speed measurement uncertainty of ground-based Rayleigh lidar during high-altitude detection.

[0008] To achieve the purpose of the present invention, the present invention provides a method for evaluating the uncertainty GUM of wind speed measurement by ground-based Rayleigh lidar, and the technical scheme adopted is as follows:

[0009] After clarifying the ground-based Rayleigh lidar wind speed measurement model and main parameters, the sources of measurement uncertainty are determined. The sources of uncertainty include: detection channel photon noise, reference channel photon noise, detection channel background noise, reference channel background noise, detection channel dead time, reference channel dead time and reference wavelength. The measurement uncertainty and sensitivity coefficient introduced by the above uncertainty sources are calculated respectively, and the measurement uncertainty components of each uncertainty source are obtained, and finally the wind speed standard measurement uncertainty is synthesized.

[0010] The present invention has the following characteristics: (1) It provides a method for evaluating the uncertainty GUM of wind speed measurement of a ground-based Rayleigh laser radar; (2) It provides a calculation formula for measurement uncertainty components and sensitivity coefficients; (3) It provides a calculation formula for the combined standard uncertainty; (4) The calculation process of the present invention is clear and simple, and is suitable for situations where the parameters of the ground-based laser radar equipment are not fully known and the amount of detection data is large; (5) The present invention has low calculation difficulty and is easy to implement software calculation, and is suitable for situations where the amount of detection data is large. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 A schematic flow chart of a method for evaluating uncertainty in wind speed measurement (GUM) of a ground-based Rayleigh lidar according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0013] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Figure 1 The following is a flow chart of a method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to a specific embodiment of the present invention. The method mainly includes the following steps:

[0015] Step 1. Define the measurement model

[0016] Rayleigh lidar wind speed measurement is generally obtained by comparing the number of echo photons in the detection channel with the number of echo photons in the reference channel.

[0017] V=f(R v )

[0018] R v =G(NB1 ,N B2 )

[0019] V is wind speed, N B1 is the number of echo photons in the detection channel; N B2 is the echo photon number of the reference channel.

[0020] Step 2. Define the detection equipment parameters

[0021] Specifically including: Rayleigh laser radar detector dead time τ; Rayleigh laser radar height resolution δz; Rayleigh laser radar accumulated pulse number L; light speed value c; reference wavelength.

[0022] Step 3. Identify sources of measurement uncertainty

[0023] Specific sources include: detection channel photon noise, reference channel photon noise, detection channel background noise, reference channel background noise, detection channel dead time, reference channel dead time and reference wavelength.

[0024] Step 4. Calculate the measurement uncertainty and sensitivity coefficient introduced by the detection channel photon noise

[0025] 4.1) Calculate the number of photons after detection channel saturation correction

[0026] The photon number N after saturation correction is calculated as follows: c1 (z).

[0027]

[0028] Among them, N R1 (z) is the number of photons of the original echo signal of Rayleigh scattering in the detection channel received by the lidar, τ is the dead time, c is the speed of light, δz is the height resolution, and L is the number of accumulated pulses.

[0029] 4.2) Calculate the number of photons after background noise correction in the detection channel

[0030] The number of photons N after background noise correction is calculated as follows: B1 (z).

[0031] N B1 (z) = N C1 (z)-B1

[0032] Among them, N c1 (z) is the number of echo photons in the detection channel after saturation correction, and B1 detection channel is the number of background light photons.

[0033] 4.3) Calculate the uncertainty introduced by the detection channel photon noise

[0034] The measurement uncertainty introduced by the photon noise in the detection channel is calculated according to the following formula.

[0035]

[0036] 4.4) Calculate the sensitivity coefficient of the measurement uncertainty component

[0037] The sensitivity coefficient c1 is calculated as follows

[0038]

[0039] 4.5) Calculate the measurement uncertainty component u1

[0040] The measurement uncertainty components are calculated as follows:

[0041] u1=c1u(N R1 (z))

[0042] Step 5. Calculate the uncertainty and sensitivity coefficient introduced by the reference channel photon noise

[0043] 5.1) Calculate the number of photons after saturation correction of the reference channel

[0044] The photon number N after saturation correction is calculated as follows: c2 (z).

[0045]

[0046] Among them, N R2 (z) is the number of photons of the original echo signal of Rayleigh scattering of the reference channel received by the lidar, τ is the dead time, c is the speed of light, δz is the height resolution, and L is the number of accumulated pulses.

[0047] 5.2) Calculate the number of photons after background noise correction in the reference channel

[0048] The number of photons N after background noise correction is calculated as follows: B2 (z).

[0049] N B2 (z) = N C2 (z)-B2

[0050] Among them, N c (z0) is the number of echo photons in the reference channel after saturation correction, and B2 is the number of background light photons in the reference channel.

[0051] 5.3) Calculate the uncertainty introduced by the reference channel photon noise

[0052] The measurement uncertainty introduced by the reference channel photon noise is calculated according to the following formula.

[0053]

[0054] 5.4) Calculate the sensitivity coefficient of the measurement uncertainty component

[0055] The sensitivity coefficient c2 is calculated as follows

[0056]

[0057] 5.5) Calculate the measurement uncertainty component u2

[0058] The measurement uncertainty components are calculated as follows:

[0059] u2=c2u(N R2 (z))

[0060] Step 6. Calculate the uncertainty and sensitivity coefficient introduced by the background noise of the detection channel

[0061] 6.1) Calculate the uncertainty introduced by the background noise of the detection channel

[0062] The measurement uncertainty introduced by background noise is calculated according to the following formula.

[0063]

[0064] 6.2) Calculate the sensitivity coefficient of the measurement uncertainty component

[0065] The sensitivity coefficient c3 is calculated as follows

[0066]

[0067] 6.3) Calculate the measurement uncertainty component u3

[0068] The measurement uncertainty components are calculated as follows:

[0069] u3=c3u(B1)

[0070] Step 7. Calculate the uncertainty and sensitivity coefficient introduced by the background noise of the reference channel. 7.1) Calculate the uncertainty introduced by the background noise of the reference channel. Calculate the measurement uncertainty introduced by the background noise according to the following formula.

[0071]

[0072] 7.2) Calculate the sensitivity coefficient of the measurement uncertainty component

[0073] The sensitivity coefficient c4 is calculated as follows

[0074]

[0075] 7.3) Calculate the measurement uncertainty component u4

[0076] The measurement uncertainty components are calculated as follows:

[0077] u4=c4u(B2)

[0078] Step 8. Calculate the uncertainty and sensitivity coefficient introduced by the dead time of the detection channel. 8.1) Calculate the uncertainty introduced by the dead time of the detection channel. Calculate the measurement uncertainty introduced by the dead time of the detection channel according to the following formula.

[0079] u(τ)=0.01ns

[0080] 8.2) Calculate the sensitivity coefficient of the measurement uncertainty component

[0081] The sensitivity coefficient c5 is calculated as follows

[0082]

[0083] 8.3) Calculate the measurement uncertainty component u5

[0084] The measurement uncertainty components are calculated as follows:

[0085] u5=c5u(τ)

[0086] Step 9. Calculate the uncertainty and sensitivity coefficient introduced by the reference channel dead time 9.1) Calculate the uncertainty introduced by the reference channel dead time. Calculate the measurement uncertainty introduced by the detection channel dead time according to the following formula.

[0087] u(τ)=0.01ns

[0088] 9.2) Calculate the sensitivity coefficient of the measurement uncertainty component

[0089] The sensitivity coefficient c6 is calculated as follows

[0090]

[0091] 9.3) Calculate the measurement uncertainty component u6

[0092] The measurement uncertainty components are calculated as follows:

[0093] u6=c6u(τ)

[0094] Step 10. Calculate the uncertainty and sensitivity coefficient introduced by the reference wavelength 10.1) Calculate the uncertainty introduced by the reference wind speed. Calculate the measurement uncertainty introduced by the reference wavelength according to the following formula.

[0095] u(λ)=0.1nm

[0096] 10.2) Calculate the sensitivity coefficient of the measurement uncertainty component

[0097] The sensitivity coefficient c7 is calculated as follows

[0098]

[0099] 10.3) Calculate the measurement uncertainty component u7

[0100] The measurement uncertainty components are calculated as follows:

[0101] u7=c7u(λ)

[0102] Step 11. Combined standard uncertainty

[0103] The combined standard uncertainty is calculated as follows:

[0104]

[0105] Step 12. Calculate the expanded uncertainty

[0106] The expanded uncertainty is calculated as follows:

[0107] U=k·u c (V)

[0108] Infinite atmospheric wind speed detections obey the normal distribution. Select the confidence probability according to the table below and check the inclusion factor k.

[0109] Table 1 Confidence probability and coverage factor correspondence table

[0110] Confidence probability p 0.999 0.9973 0.99 0.954 0.95 0.90 0.683 0.6745 Inclusion factor k 3.3 3 2.58 2 1.96 1.645 1 0.5

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh lidar GUM, characterized in that: After clarifying the ground-based Rayleigh lidar wind speed measurement model and main parameters, determine the sources of measurement uncertainty, which include: detection channel photon noise, reference channel photon noise, detection channel background noise, reference channel background noise, detection channel dead time, reference channel dead time and reference wavelength. Calculate the measurement uncertainty and sensitivity coefficient introduced by the above uncertainty sources respectively, obtain the measurement uncertainty components of each uncertainty source, and finally synthesize the wind speed standard measurement uncertainty. Among them, the ground-based Rayleigh lidar wind speed measurement model is: V=f(R v ) R v =G(N B1 ,N B2 ) V is wind speed, N B1 is the number of echo photons in the detection channel; N B2 is the echo photon number of the reference channel.

2. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 1 is characterized in that: The calculation method of the measurement uncertainty component introduced by the detection channel photon noise is as follows: 1) Calculate the number of photons N after detection channel saturation correction c1 (z) Among them, N R1 (z) is the number of photons of the original echo signal of Rayleigh scattering in the detection channel received by the lidar, τ is the dead time, c is the speed of light, δz is the height resolution, and L is the number of accumulated pulses; 2) Calculate the number of photons N after background noise correction in the detection channel B1 (z) N B1 (from)=N C1 (from)-B1 Among them, N c1 (z) is the number of echo photons in the detection channel after saturation correction, and B1 detection channel is the number of background light photons; 3) Calculate the measurement uncertainty introduced by the detection channel photon noise 4) Calculate the sensitivity coefficient c1 of the measurement uncertainty component 5) Calculate the measurement uncertainty component u1 u1=c1u(N R1 (with)).

3. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 1 is characterized in that: The measurement uncertainty component introduced by the reference channel photon noise is calculated as follows: 1) Calculate the number of photons N after saturation correction of the reference channel c2 (z) Among them, N R2 (z) is the number of photons of the original echo signal of Rayleigh scattering in the reference channel received by the lidar, τ is the dead time, c is the speed of light, δz is the height resolution, and L is the number of accumulated pulses; 2) Calculate the number of photons N after background noise correction in the reference channel B2 (z) N B2 (z)=N C2 (z)-B2 Among them, N c (z0) is the number of echo photons in the reference channel after saturation correction, and B2 is the number of background light photons in the reference channel; 3) Calculate the measurement uncertainty introduced by the reference channel photon noise 4) Calculate the sensitivity coefficient c2 of the measurement uncertainty component 5) Calculate the measurement uncertainty component u2 <h2 style=";text-align:left;direction:ltr">u2=c2u(N<h2 style=";text-align:left;direction:ltr"> R2 <h2 style=";text-align:left;direction:ltr"> (z))。 4. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 2 is characterized in that: The calculation method of the measurement uncertainty component introduced by the background noise of the detection channel is as follows: 1) Calculate the measurement uncertainty introduced by the background noise of the detection channel 2) Calculate the sensitivity coefficient c3 of the measurement uncertainty component 3) Calculate the measurement uncertainty component u3 u3=c3u(B1).

5. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 3 is characterized in that: The measurement uncertainty component introduced by the background noise of the reference channel is calculated as follows: 1) Calculate the measurement uncertainty introduced by the background noise of the reference channel 2) Calculate the sensitivity coefficient c4 of the measurement uncertainty component 3) Calculate the measurement uncertainty component u4 u4=c4u(B2).

6. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 2 is characterized in that: The calculation method of the measurement uncertainty component introduced by the detection channel dead time is as follows: 1) Calculate the measurement uncertainty introduced by the detection channel dead time u(τ)=0.01ns 2) Calculate the sensitivity coefficient c5 of the measurement uncertainty component 3) Calculate the measurement uncertainty component u5 u5=c5u(τ) 7. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 3 is characterized in that: The measurement uncertainty component introduced by the reference channel dead time is calculated as follows: 1) Calculate the measurement uncertainty introduced by the reference channel dead time u(τ)=0.01ns 2) Calculate the sensitivity coefficient c6 of the measurement uncertainty component 3) Calculate the measurement uncertainty component u6 The measurement uncertainty components are calculated as follows: u6=c6u(τ).

8. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 1 is characterized in that: The measurement uncertainty component introduced by the reference wavelength is calculated as follows: 1) Calculate the measurement uncertainty introduced by the reference wind speed u(λ)=0.1nm 2) Calculate the sensitivity coefficient c7 of the measurement uncertainty component 3) Calculate the measurement uncertainty component u7 u7=c7u(λ).

9. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 1, characterized in that: The calculation method of the combined standard uncertainty is: Among them, u1 is the measurement uncertainty component introduced by the photon noise of the detection channel, u2 is the measurement uncertainty component introduced by the photon noise of the reference channel, u3 is the measurement uncertainty component introduced by the background noise of the detection channel, u4 is the measurement uncertainty component introduced by the background noise of the reference channel, u5 is the measurement uncertainty component introduced by the dead time of the detection channel, u6 is the measurement uncertainty component introduced by the dead time of the reference channel, and u7 is the measurement uncertainty component introduced by the reference wavelength.

10. The method for evaluating the uncertainty of wind speed measurement by ground-based Rayleigh laser radar GUM according to claim 9, characterized in that: The expanded uncertainty calculation method is as follows: U=k·u c (V) in, u c (V) is the standard measurement uncertainty of wind speed, K is the inclusion factor. Infinite atmospheric wind speed detections obey the normal distribution. Select the confidence probability p according to the table below to obtain the inclusion factor k. Confidence probability and coverage factor correspondence table 。

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