Ozone laser radar calibration method and system

Abstract

The embodiment of the invention provides an ozone laser radar calibration method and system, and is applied to the technical field of laser radar calibration. The method comprises the following steps: acquiring multiple groups of ozone data in the horizontal direction acquired by an ozone laser radar; calculating geometric factor data of the ozone laser radar according to the ozone data; fitting calculation is carried out on the geometric factor data to obtain geometric factor curves, and geometric factor curves meeting a preset condition interval in the geometric factor curves are intercepted; and correcting the geometric factor curve meeting the preset condition interval, and calibrating the ozone laser radar by using the corrected geometric factor curve. In this way, errors existing in data inversion caused by geometric factor differences between receiving channels of the calibration ozone laser radar on the near ground can be achieved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of laser radar calibration, in particular to a calibration method and system of ozone laser radar. BACKGROUND

[0002] Ozone laser radar is an atmospheric detection instrument used in the field of earth science. It measures the concentration distribution of gas based on the principle of differential absorption and the absorption characteristics of ozone. This radar transmits two groups of pulsed laser with similar wavelengths by a high-energy ultraviolet laser, one wavelength on the strong absorption line of ozone and the other on the weak absorption line. By analyzing the absorption difference of ozone to the two wavelengths, the concentration of ozone on the common path of the two pulsed lasers can be determined, thereby realizing the three-dimensional detection of atmospheric ozone. Ozone laser radar has the ability to monitor the vertical distribution of atmospheric ozone concentration in real time and online, and the lower limit of ozone detection can reach ppb level. It has the advantages of large measurement range, high resolution, high precision, remote real-time, etc.

[0003] The geometric factors received by the two channels in the differential absorption laser radar are not exactly the same, which will cause a certain deviation in the inversion of pollutant concentration in the near distance range. Correcting the geometric factor can effectively improve the detection accuracy of ozone radar in the near distance range. Therefore, there is an urgent need for a calibration method of ozone laser radar. SUMMARY

[0004] The present disclosure provides a calibration method and system of ozone laser radar, which solves the technical problem of data inversion error caused by the difference in geometric factors between the receiving channels of ozone laser radar near the ground.

[0005] According to a first aspect of the present disclosure, a calibration method of ozone laser radar is provided. The method comprises:

[0006] Obtaining multiple groups of horizontal direction ozone data collected by the ozone laser radar;

[0007] Calculating the geometric factor data of the ozone laser radar according to the ozone data;

[0008] Fitting the geometric factor data to obtain a geometric factor curve, and intercepting the geometric factor curve in the geometric factor curve that meets the preset condition interval;

[0009] Correcting the geometric factor curve that meets the preset condition interval, and calibrating the ozone laser radar using the corrected geometric factor curve.

[0010] According to the aspect and any possible implementation manner above, further provided is an implementation manner, wherein the fitting calculation on the geometric factor data obtains a geometric factor curve, and the geometric factor curve in the interval meeting the preset condition is obtained by intercepting the geometric factor curve, which includes:

[0011] selecting reference points on the geometric factor curve according to a preset interval;

[0012] calculating a determination coefficient of each of the reference points;

[0013] selecting a plurality of continuous reference points with the determination coefficient greater than a preset threshold value;

[0014] intercepting the geometric factor curve from a first reference point to a last reference point.

[0015] According to the aspect and any possible implementation manner above, further provided is an implementation manner, wherein the selecting a plurality of continuous reference points with the determination coefficient greater than a preset threshold value includes:

[0016] determining whether the number of continuous reference points on the geometric factor curve is greater than a preset minimum number of continuous reference points, and if yes, intercepting the geometric factor curve; otherwise, stopping the intercepting of the geometric factor curve.

[0017] According to the aspect and any possible implementation manner above, further provided is an implementation manner, wherein the correcting the interval geometric factor curve includes:

[0018] inverting an ozone concentration according to the interval geometric factor curve by using a laser radar equation;

[0019] calculating an extinction difference value according to the ozone concentration and a difference between absorption cross sections of ozone at two wavelengths; wherein the extinction difference value is a difference between extinction coefficients at the two wavelengths of the laser radar caused by the ozone;

[0020] correcting the geometric factor curve in combination with the extinction difference value.

[0021] According to the aspect and any possible implementation manner above, further provided is an implementation manner, wherein the correcting the geometric factor curve in combination with the extinction difference value includes:

[0022] processing a strong absorption wavelength cross section of the ozone absorption band according to the extinction difference value;

[0023] normalizing a ratio between a weak absorption wavelength geometric factor and the processed strong absorption wavelength geometric factor to obtain a geometric factor ratio;

[0024] correcting the geometric factor curve by using the geometric factor ratio.

[0025] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, and the method further comprises: after the horizontal-direction ozone data is acquired, performing signal distortion judgment on the ozone data; if the ozone data is distorted, performing automatic resampling operation; wherein the signal distortion judgment comprises:

[0026] According to a vertical distribution model of atmospheric molecules, a laser radar signal generated by molecular scattering is calculated, and the collected data and the scattering signal are respectively taken logarithm and then compared;

[0027] and / or within a detection distance satisfying a predetermined signal-to-noise ratio requirement, a far-field signal is selected to perform linear fitting to obtain a slant line, and whether the collected data slant line deviates from the slant line obtained by fitting is judged;

[0028] and / or after the collected data is removed from the background, the collected data is smoothed and denoised, and logarithm is taken, and whether data above a preset threshold is horizontal is judged.

[0029] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, and the method further comprises: after the ozone laser radar is calibrated by using the corrected interval geometric factor curve, the method comprises:

[0030] The ozone data is inversed by using the corrected interval geometric factor curve;

[0031] Ozone data is collected by using an ozone detection device at a fixed point on an ozone measurement path;

[0032] The inversed ozone data is compared with the ozone data collected by the ozone detection device;

[0033] According to a comparison result, whether the inversed ozone data is accurate is detected.

[0034] According to a second aspect of the present disclosure, a calibration system of an ozone laser radar is provided. The system comprises:

[0035] An acquisition module is configured to acquire a plurality of groups of horizontal-direction ozone data collected by an ozone laser radar;

[0036] A calculation module is configured to calculate geometric factor data of the ozone laser radar according to the ozone data;

[0037] A cutting module is configured to perform fitting calculation on the geometric factor data to obtain a geometric factor curve, and cut an interval geometric factor curve in the geometric factor curve that meets a preset condition;

[0038] A calibration module is configured to correct the interval geometric factor curve, and calibrate the ozone laser radar by using the corrected interval geometric factor curve.

[0039] According to a third aspect of the present disclosure, an electronic device is provided. The electronic device comprises a memory and a processor, the memory having stored thereon a computer program, the processor implementing the method as described above when executing the program.

[0040] According to a fourth aspect of the present disclosure, a computer readable storage medium is provided, having stored thereon a computer program, the program, when executed by a processor, implementing the method according to the first and / or second aspect of the present disclosure.

[0041] The present disclosure calculates geometric factor data according to multiple groups of horizontal direction ozone data collected by an ozone laser radar, then fits a geometric factor curve using the geometric factor data, intercepts a geometric factor curve in a range that meets the conditions, corrects the geometric factor curve in the range, and finally calibrates the ozone laser radar using the corrected geometric factor curve in the range. By correcting the geometric factor in the transition zone, the data inversion error caused by the difference in geometric factor near the ground is solved, thereby effectively improving the detection accuracy of the ozone laser radar in the near-ground range.

[0042] It should be understood that the content described in the summary section is not intended to limit the key or important features of the embodiments of the present disclosure, nor to limit the scope of the present disclosure. Other features of the present disclosure will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0043] The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent by describing in detail the following embodiments with reference to the attached drawings. The drawings are intended to better understand the present disclosure and do not limit the present disclosure, and the same or similar reference numerals refer to the same or similar elements throughout the drawings, in which:

[0044] Figure 1 A flowchart of a calibration method of an ozone laser radar according to an embodiment of the present disclosure is shown;

[0045] Figure 2 A geometric factor fitting curve diagram in an embodiment of the present disclosure is shown;

[0046] Figure 3 A geometric factor diagram of an ozone radar system before correction in an embodiment of the present disclosure is shown;

[0047] Figure 4 A geometric factor diagram of an ozone radar system after correction in an embodiment of the present disclosure is shown;

[0048] Figure 5 A comparison diagram of an ln(PRR) signal actually measured by a laser radar and a molecular scattering signal in an embodiment of the present disclosure is shown;

[0049] Figure 6 A schematic diagram of signal baseline deformation in a dark environment is shown according to an embodiment of the present disclosure;

[0050] Figure 7 A schematic diagram of high-altitude tailing caused by low-altitude signals is shown according to an embodiment of the present disclosure;

[0051] Figure 8 A block diagram of a calibration system of an ozone lidar according to an embodiment of the present disclosure is shown;

[0052] Figure 9 A block diagram of an exemplary electronic device capable of implementing an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0053] To make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are some but not all of the embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0054] In addition, the term "and / or" herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0055] In the present disclosure, geometric factor data is calculated according to multiple groups of horizontal direction ozone data collected by an ozone lidar, a geometric factor curve is fitted using the geometric factor data, the geometric factor curve in the interval that meets the conditions is intercepted, and the geometric factor curve in the interval is corrected. The ozone lidar is calibrated using the corrected geometric factor curve.

[0056] Figure 1 A flowchart of a calibration method 100 of an ozone lidar according to an embodiment of the present disclosure is shown. As shown in Figure 1 The calibration method of the ozone lidar includes:

[0057] S101, multiple groups of horizontal direction ozone data collected by an ozone lidar are acquired.

[0058] In some embodiments, the radar correction geometry factor needs to be used in clear weather and clean air, using ozone laser radar to emit laser in horizontal direction at two wavelengths, one of which is located on the strong absorption line of ozone, and the other is located on the weak absorption line of ozone. Then the backscattering signals after the laser interacts with the atmosphere are received by the receiving telescope, and a plurality of sets of ozone data in the horizontal direction are calculated by the backscattering signals at two wavelengths. Among them, the plurality of sets of ozone data refers to the backscattering signals at different distances of the ozone laser radar at two wavelengths, and finally the ozone data at different distances is calculated.

[0059] S102, calculating the geometry factor data of the ozone laser radar according to the ozone data.

[0060] In some embodiments, the geometry factor data of the ozone laser radar is calculated according to the ozone data using a geometry factor calculation tool.

[0061] Because the geometry factors of the receiving telescope for the backscattering signal receiving channels of the two wavelengths are not exactly the same, the geometry factor data calculated by the geometry factor calculation tool has some errors from the real data.

[0062] Specifically, because the optical paths of the two channels do not completely coincide, which will cause the geometry factors of the two channels at the same distance to be different, so when calculating the geometry factor data, independent calculation needs to be performed on the backscattering signals of the two wavelengths respectively, to obtain two sets of geometry factor data.

[0063] Among them, the geometry factor reflects the receiving efficiency of the laser radar for the backscattering signals at different distances. In the near-surface, because the emission beam and the receiving field of view may not completely overlap, the geometry factor data will be small and gradually change with the distance; to the far-surface, when the emission beam completely falls into the receiving field of view, the geometry factor reaches a stable value.

[0064] Further, assuming that the horizontal atmosphere is uniform, the laser radar equation considering the geometry factor can be written as:

[0065] P (z) =Y (z) Cβ H / Z 2 exp(-2α H ) (1)

[0066] Among them, P (z) is the received signal intensity at a distance z, Y (z) is the geometry factor, C is the system constant, β H is the atmospheric backscattering coefficient, and α H is the extinction coefficient.

[0067] After the laser radar enters the full signal receiving area, that is, z>z′, z′ is the height of the transition area, ln(Pz 2 ) and z are fitted by least squares to obtain the slope k and intercept b of the fitting line. Within the transition zone, the signal P′ received by the lidar (z) Expressed as:

[0068] P′ (z) =exp(k*z+b) / z 2 (2)

[0069] Combining formulas (1) and (2), the geometric factor of the lidar is expressed as:

[0070]

[0071] Among them, the transition zone represents the area where the ozone lidar receiving signal transitions from "partial reception of atmospheric backscattered signals" to "full reception". In this area, the geometric factor changes significantly with distance, and the receiving efficiency has not reached a stable state, which will affect the accuracy of near-ground data.

[0072] S103, performing fitting calculation on the geometric factor data to obtain a geometric factor curve, and intercepting a geometric factor curve that meets a preset condition interval in the geometric factor curve.

[0073] In some embodiments, to facilitate processing of the geometric factor, it is necessary to perform fitting calculations on the geometric factor data to obtain a geometric factor curve. To improve the accuracy of the correction, it is necessary to intercept one or more geometric factor curves with a high goodness of fit of the regression model for geometric factor correction.

[0074] Specifically, Figure 2 The figure shows a schematic diagram of a geometric factor fitting curve according to an embodiment of the present disclosure, wherein the horizontal axis is the detection distance and the vertical axis is ln(PR 2 ), where 0.0532.p represents the geometric factor curve of the strong absorption wavelength, which is significantly affected by ozone absorption and has a larger absolute value of slope; 0.0532.s represents the geometric factor curve of the weak absorption wavelength, which is dominated by aerosol scattering and has a smaller absolute value of slope.

[0075] Further, by Figure 2 It can be seen that in the area with a distance of 517.5m-1282.5m from the ozone lidar, the data points are closely distributed near the fitting curve, the deviation is small, and the curve trend is smooth without drastic fluctuations. Therefore, the area with higher fitting goodness of fit is the area with a distance of 517.5m-1282.5m from the ozone lidar.

[0076] In some embodiments, performing fitting calculation on the geometric factor data to obtain a geometric factor curve, and intercepting an interval geometric factor curve that meets a preset condition in the geometric factor curve includes:

[0077] Selecting reference points on the geometric factor curve according to a preset interval;

[0078] Calculating the determination coefficients of the plurality of reference points respectively;

[0079] Selecting a plurality of consecutive reference points whose determination coefficient is greater than a preset threshold;

[0080] The geometric factor curve is intercepted with the first reference point as the starting point and the last reference point as the end point.

[0081] Specifically, the calibration method in this embodiment must be performed in a clear, clean environment. In particular, the geometry factor curve involved in the correction must meet the preset conditions. Therefore, it is important to select the appropriate portion of the geometry factor curve when intercepting it, otherwise the correction data will be inaccurate.

[0082] Furthermore, the coefficient of determination is a key indicator for measuring the goodness of fit of the geometric factor data fitting curve, and its calculation formula is:

[0083]

[0084] Where y i represents the actual observed value, represents the predicted value of the regression model, is the mean of the observed values.

[0085] The range of the determination coefficient is [0, 1], R 2 =1 means the fitting curve fits all data points perfectly, R 2 =0 means the fitted curve is completely unrelated to the data. Using the determination coefficient rather than subjective judgment to select the curve interval makes the calibration process more objective and repeatable, avoiding the arbitrariness of manually selected intervals.

[0086] Specifically, Figure 3 FIG1 shows a schematic diagram of the geometric factor of the ozone radar system before correction according to an embodiment of the present disclosure, wherein the horizontal axis is the dimensionless parameter and the vertical axis is the normalized geometric factor value. Figure 3 It can be seen that a reference point is taken at intervals of 0.1km, and the determination coefficient of multiple reference points is calculated. Multiple consecutive reference points with a determination coefficient greater than 0.999 are selected to ensure high data reliability. Finally, the interval geometric factor curve is intercepted with the first and last reference points that meet the conditions as endpoints. Among them, the spacing needs to be adjusted according to the resolution of the lidar. Usually, the signal stable interval is selected. Uniform sampling can cover the entire detection range and reduce the amount of data processing.Figure 3 In the interval of 0.5km-2.0km, the determination coefficient is greater than 0.999, so the geometric factor in the interval is intercepted for correction. In some embodiments, the selecting the plurality of continuous reference points with the determination coefficient greater than the preset threshold value comprises:

[0087] Determining whether the number of continuous reference points on the geometric factor curve is greater than the preset minimum number of continuous reference points. If yes, the geometric factor curve is intercepted; otherwise, the geometric factor curve interception is stopped.

[0088] Specifically, not all collected data can be intercepted to obtain a suitable geometric factor interval for geometric factor correction. For example, on a cloudy day, the determination coefficient may be low, and calibration is not suitable at this time. Therefore, the minimum number of continuous reference points with the determination coefficient greater than 0.999 is determined according to the predetermined interval. If the number of continuous reference points on the geometric factor curve is greater than the minimum number, the next step is performed; if the number of continuous reference points on the geometric factor curve is less than the minimum number, it indicates that the collection environment does not meet the calibration requirements.

[0089] S104, correcting the geometric factor curve in the interval, and calibrating the ozone laser radar using the corrected geometric factor curve.

[0090] In some embodiments, the correcting the interval geometric factor curve comprises:

[0091] Inverting the ozone concentration from the interval geometric factor curve according to the laser radar equation;

[0092] Calculating an extinction difference value according to the ozone concentration and the difference in absorption cross-section of ozone at two wavelengths; wherein the extinction difference value is the difference in extinction coefficient at two wavelengths of the laser radar caused by the influence of ozone;

[0093] Correcting the geometric factor curve in combination with the extinction difference value.

[0094] In some embodiments, the correcting the geometric factor curve in combination with the extinction difference value comprises:

[0095] Processing the strong absorption wavelength cross-section of the ozone absorption band according to the extinction difference value;

[0096] Normalizing the ratio of the geometric factor of the weak absorption wavelength to the processed geometric factor of the strong absorption wavelength to obtain a geometric factor ratio;

[0097] Correcting the geometric factor curve using the geometric factor ratio.

[0098] Specifically, the ozone concentration N(z) in the interception interval is inversed by the laser radar equation, and the formula is as follows:

[0099]

[0100] The absorption cross sections of ozone for two wavelengths are different, resulting in different extinction coefficients of the two channels, which can be expressed by the following formula:

[0101] Δα(z)=N(z)·(σ 强 -σ 弱 ) (6)

[0102] In the formula, N(z) is the inversed ozone concentration, σ 强 is the strong absorption wavelength, σ 弱 is the weak absorption wavelength, and Δα(z) is the extinction difference value.

[0103] The strong absorption wavelength signal is more affected by ozone absorption, and the ozone absorption contribution needs to be removed to extract the pure geometric factor part. The extinction coefficient of the strong absorption wavelength is corrected using the extinction difference value. The processed strong absorption wavelength cross section no longer contains the influence of the dynamic change of the ozone concentration, and the geometric factor ratio can be expressed by the following formula:

[0104]

[0105] In the formula, η 强 , 矫正 (z) is the corrected strong absorption wavelength geometric factor, η 弱 (z) represents the weak absorption wavelength geometric factor, and R(z) is normalized to eliminate the influence of random noise.

[0106] In some embodiments, the ozone lidar inverses the ozone concentration by the absorption difference of the two wavelengths, but if the geometric factors of the two channels are inconsistent, the inversion result will deviate from the true value. By multiplying the geometric factor at each distance by the geometric factor ratio, the geometric factors of the two wavelength channels tend to be consistent, and the dynamic range of the received atmospheric backscatter signal in the transition zone is reduced.

[0107] Specifically, Figure 4 Fig. 3 shows a schematic diagram of the geometric factor of the corrected ozone radar system according to an embodiment of the present disclosure, and it can be seen from Figure 4 that after 0.5 km, the atmospheric backscatter signal completely enters the receiving field of view. Figure 4The ozone profile inversions before and after the correction of the geometric factor of the ozone lidar are compared, and it can be seen from the figure that the inversion of the ozone concentration value is larger and changes within the detection distance of 500m without the correction of the geometric factor, and the correction is good within the range of 300m-500m after the correction of the channel geometric factor, but there is still a certain deviation within 300m. The deviation near the end is caused by the larger geometric factor error near the end. It can be seen that the appropriate geometric factor of the lidar can effectively prevent the over-strong signal near the ground to some extent and protect the detector.

[0108] In some embodiments, in order to ensure the accuracy of the calibration data, the calibration of the ozone lidar by the corrected geometric factor curve further comprises the following steps:

[0109] The ozone data is inversed by the corrected geometric factor curve; wherein the ozone data includes ozone concentration value, ozone concentration change trend and correlation;

[0110] The ozone data is collected by the ozone detection device at the fixed point on the ozone measurement path;

[0111] The inversed ozone data is compared with the ozone data collected by the ozone detection device;

[0112] According to the comparison result, it is detected whether the inversed ozone data is accurate.

[0113] Specifically, the data detected by the ozone detection device is relatively accurate, the ozone data is inversed by the corrected geometric factor, and then the ozone data is compared with the accurate data measured to verify, which can further improve the accuracy of the calibration.

[0114] In some embodiments, in order to further improve the accuracy of the calibration, the collected ozone data must be effectively judged to prevent the calibration error caused by the distortion of the low-altitude signal. There are three types of signal distortion for the ozone detection lidar, the first type is saturation distortion, when the low-altitude backscattering light received by the lidar is strong, it may exceed the linear response range of the detector, causing the measured signal to be lower than the actual value, and even the signal is saturated, this type of distortion is common in AD and PC detection systems; the second type is electronic baseline deformation, the detection and collection system is disturbed by electromagnetic interference, causing the baseline to deform and superimpose on the signal to cause distortion, this type of distortion is common in AD detection system; the third type is signal induced bias (SIB) phenomenon, when the low-altitude PC signal is too large, it will cause the PMT to produce slightly delayed additional electronic excitation in time sequence, thereby superimposing a tail-shaped "false signal" on the real high-altitude signal, this type of distortion can be seen in AD and PC detection systems. In this embodiment, the three types of distortion are judged.

[0115] In some embodiments, the method further comprises: after acquiring the horizontal direction ozone data, performing signal distortion judgment on the ozone data; if the ozone data is distorted, performing automatic resampling operation; wherein the signal distortion judgment comprises:

[0116] According to the vertical distribution model of atmospheric molecules, the laser radar signal generated by molecular scattering is calculated, and the collected data and the scattering signal are taken logarithm and then compared;

[0117] and / or in the detection distance meeting the predetermined requirement of signal-to-noise ratio, a far field signal is selected to perform linear fitting to obtain a slant line, and whether the slant line of the collected data deviates from the slant line obtained by fitting is judged;

[0118] and / or after removing the background, the collected data is smoothed and denoised, and logarithm is taken, and whether the data above the preset threshold is horizontal is judged.

[0119] Specifically, the molecular scattering signal P mol (z) is calculated as follows:

[0120]

[0121] In the formula, C is a constant of the laser radar system; β m and α m are the backscattering coefficient and the extinction coefficient of atmospheric molecules, respectively, wherein β m can be calculated by a standard atmospheric model:

[0122]

[0123] In the formula, λ is the wavelength of laser (m); ρ(z) and ρ0 are the air molecule density at height z and sea level respectively (kg / m3); N(z) is the air molecule number density at height z (m -3 ). ρ(z) and N(z) can be calculated by atmospheric temperature T and pressure p:

[0124]

[0125] In the formula, K=1.380649×10 -23 Boltzmann constant; NA=6.02214×10 23 Avogadro constant; M=28.964 is the average molecular weight of atmospheric molecules.

[0126] The distance square signal (PRR) of the laser radar decays according to an approximate exponential law with height, and the signal is taken logarithm, then decays according to a linear law, which is more convenient for observing distortion phenomenon. Figure 5The ln(PRR) signal measured by the laser radar and the molecular scattering signal are shown in the contrast diagram according to the embodiment of the present disclosure. It can be seen that the two can be well overlapped at high altitude above 6km, but below 6km, the measured signal is "concave" downward, which represents that the measured signal is smaller than the theoretical value, which may be caused by the saturation distortion of the detector, or may be because the electronic baseline of the near-field signal is inclined downward.

[0127] To further determine the cause of signal distortion, the laser intensity can be reduced for observation. If the signal distortion phenomenon is eliminated or improved, it indicates that the phenomenon is caused by the excessive near-field light signal. In addition, the telescope can be covered for measurement to observe whether the signal baseline in the dark environment is horizontal, Figure 6 The schematic diagram of signal baseline deformation in the dark environment according to the embodiment of the present disclosure is shown.

[0128] Specifically, when the weather is fine and the atmospheric water level is uniform, the instrument with test conditions can be used for horizontal detection. Within the detection distance meeting the signal-to-noise ratio requirement, a far-field ln(PRR) signal with a length of 2-3km is selected for linear fitting to obtain a slant line. In the case of uniform atmospheric water level, the effective signal outside the geometric factor area should be substantially coincided with the slant line. If the measured signal deviates from the fitted slant line, it is considered whether the signal distortion phenomenon occurs.

[0129] Specifically, the signal is smoothed and denoised after background removal and logarithm is taken to obtain ln(P). The SNR of the channel is less than 3 above 1.7km, and the part above 3km can be regarded as a background signal in principle. However, the signal in the range of about 2-12km in the figure is inclined downward, which is the high-altitude tailing phenomenon caused by low-altitude signal, Figure 7 The schematic diagram of high-altitude tailing phenomenon caused by low-altitude signal according to the embodiment of the present disclosure is shown.

[0130] According to the embodiment of the present disclosure, by correcting the geometric factor of the transition area, the data inversion error caused by the difference of the geometric factor near the ground is solved, thereby effectively improving the detection accuracy of the ozone laser radar in the near-ground range.

[0131] It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present disclosure is not limited by the action sequence described, because according to the present disclosure, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0132] The above is the introduction of the method embodiment, and the following further describes the scheme of the present disclosure through the device embodiment.

[0133] Figure 8 A block diagram of a calibration system of an ozone lidar is shown in accordance with an embodiment of the present disclosure. As shown, the device 800 includes: Figure 8

[0134] The acquisition module 801 is configured to acquire a plurality of groups of horizontal-direction ozone data collected by the ozone lidar.

[0135] The calculation module 802 is configured to calculate geometric factor data of the ozone lidar according to the ozone data.

[0136] The intercepting module 803 is configured to perform fitting calculation on the geometric factor data to obtain a geometric factor curve, and intercept a geometric factor curve in the geometric factor curve that meets a preset condition interval.

[0137] The calibration module 804 is configured to correct the geometric factor curve that meets the preset condition interval, and calibrate the ozone lidar by using the corrected geometric factor curve.

[0138] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described modules can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0139] In the technical scheme of the present disclosure, the acquisition, storage and application of user personal information involved comply with relevant laws and regulations and do not violate public order and good customs.

[0140] According to the embodiments of the present disclosure, the present disclosure further provides an electronic device, a readable storage medium and a computer program product.

[0141] Figure 9 A schematic block diagram of an electronic device 900 that can be used to implement embodiments of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptops, desktops, tablets, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular telephones, smart phones, wearable devices, and other similar computing devices. The components shown here, their connections and relationships, and their functions, are meant to be examples only, and are not intended to limit the implementations of the present disclosure described and / or claimed in this document.

[0142] ​The electronic device 900 includes a computing unit 901 that can perform various appropriate actions and processes in accordance with a computer program stored in the ROM 902 or a computer program loaded into the RAM 903 from the storage unit 908. In the RAM 903, various programs and data required for the operation of the electronic device 900 can also be stored. The computing unit 901, the ROM 902, and the RAM 903 are connected to each other through a bus 904. An I / O interface 905 is also connected to the bus 904.

[0143] A plurality of components in the electronic device 900 are connected to the I / O interface 905, including an input unit 906 such as a keyboard, a mouse, and the like, an output unit 907 such as various types of displays, a speaker, and the like, a storage unit 908 such as a magnetic disk, an optical disk, and the like, and a communication unit 909 such as a network card, a modem, a wireless communication transceiver, and the like. The communication unit 909 allows the electronic device 900 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0144] The computing unit 901 can be various general-purpose and / or special-purpose processing components having processing and computing capabilities. Some examples of the computing unit 901 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, and the like. The computing unit 901 performs various methods and processes described above, such as the method 100. For example, in some embodiments, the method 100 can be implemented as a computer software program that is tangibly embodied in a machine-readable medium, such as the storage unit 908. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 900 via the ROM 902 and / or the communication unit 909. When the computer program is loaded into the RAM 903 and executed by the computing unit 901, one or more steps of the method 100 described above can be performed. Alternatively, in other embodiments, the computing unit 901 can be configured to perform the method 100 by any other appropriate means, such as by means of firmware.

[0145] The various embodiments of the systems and techniques described above can be implemented in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a load programmable logic device (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0146] Program code for carrying out methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces the functions / operations specified in the flowcharts and / or the block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0147] In the context of the present disclosure, a machine-readable medium can be a tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0148] To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0149] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet.

[0150] The computer system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server is generally established by computer programs running on the respective computers and having a client-server relationship to each other. The servers can be cloud servers, servers of a distributed system, or servers combined with a blockchain.

[0151] It should be understood that the various forms of flow shown above can be re-ordered, added to, or deleted from without departing from the scope of the present disclosure. For example, the steps recited in the present disclosure can be performed in parallel, in series, or in a different order, without departing from the desired results of the technical solutions of the present disclosure, and are not limited herein.

[0152] The specific embodiments described above are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that various modifications, combinations, sub-combinations, and alternatives can be made to the specific embodiments without departing from the spirit and principles of the present disclosure. Any further modifications, equivalent substitutions, improvements, and the like, which are within the spirit and principles of the present disclosure are to be encompassed by the following claims.

Claims

1. A calibration method for an ozone lidar, comprising: Obtain multiple sets of horizontal ozone data collected by the ozone lidar; Calculating geometric factor data of the ozone lidar based on the ozone data; Performing fitting calculation on the geometric factor data to obtain a geometric factor curve, and intercepting a geometric factor curve that meets a preset condition interval in the geometric factor curve; The geometric factor curve that meets the preset condition interval is corrected, and the ozone laser radar is calibrated using the corrected geometric factor curve.

2. The method according to claim 1, characterized in that The step of fitting the geometric factor data to obtain a geometric factor curve and intercepting a geometric factor curve that meets a preset condition interval in the geometric factor curve includes: Selecting reference points on the geometric factor curve according to a preset interval; Calculating the determination coefficients of the plurality of reference points respectively; Selecting a plurality of consecutive reference points whose determination coefficient is greater than a preset threshold; The geometric factor curve is intercepted with the first reference point as the starting point and the last reference point as the end point.

3. The method according to claim 2, characterized in that The selecting of a plurality of continuous reference points whose determination coefficient is greater than a preset threshold comprises: It is determined whether the number of continuous reference points on the geometric factor curve is greater than a preset minimum number of continuous reference points. If so, the geometric factor curve is intercepted; otherwise, the geometric factor curve is stopped.

4. The method according to claim 1, wherein The correcting of the geometric factor curve that meets the preset condition interval includes: The ozone concentration is inverted according to the interval geometric factor curve through the lidar equation; Calculating an extinction difference value based on the ozone concentration and the difference in the absorption cross section of ozone at the two wavelengths; wherein the extinction difference value is the difference in the extinction coefficient of the laser radar at the two wavelengths caused by the influence of ozone; The geometric factor curve is corrected in combination with the extinction difference value.

5. The method according to claim 4, characterized in that The correcting the geometric factor curve in combination with the extinction difference value includes: processing a strong absorption wavelength cross section of the ozone absorption band according to the extinction difference value; Normalize the ratio of the geometric factor of the weak absorption wavelength to the geometric factor of the processed strong absorption wavelength to obtain the geometric factor ratio; The geometric factor curve is corrected using the geometric factor ratio.

6. The method according to claim 1, characterized in that The method further includes: after acquiring ozone data in the horizontal direction, performing a signal distortion determination on the ozone data; if the ozone data is distorted, performing an automatic resampling operation; wherein the signal distortion determination includes: The lidar signal generated by molecular scattering is calculated based on the vertical distribution model of atmospheric molecules. The collected data and the scattered signal are taken logarithmically and then compared. and / or within a detection distance that satisfies predetermined signal-to-noise ratio requirements, selecting a far-field signal for linear fitting to obtain a slant line, and determining whether the slant line of the collected data deviates from the fitted slant line; And / or the collected data is smoothed and denoised after background removal, and the logarithm is taken to determine whether the data above a preset threshold is horizontal.

7. The method according to claim 1, characterized in that The method further includes: calibrating the ozone laser radar using the corrected interval geometry factor curve, and then: Inverting the ozone data using the corrected interval geometry factor curve; Use ozone detection devices to collect ozone data at fixed points along the ozone measurement path; Compare the inverted ozone data with the ozone data collected by the ozone detection device; The accuracy of the inverted ozone data is checked based on the comparison results.

8. A calibration system for an ozone laser radar, comprising: An acquisition module is used to obtain multiple sets of horizontal ozone data collected by the ozone lidar; A calculation module, configured to calculate geometric factor data of the ozone lidar based on the ozone data; An interception module is used to perform fitting calculation on the geometric factor data to obtain a geometric factor curve, and intercept a geometric factor curve that meets a preset condition interval in the geometric factor curve; The calibration module is used to correct the geometric factor curve that meets the preset condition interval and calibrate the ozone laser radar using the corrected geometric factor curve.

9. An electronic device comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1-7.

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