Sulfur dioxide concentration inversion method capable of resisting influence of light dilution effect

Abstract

The invention belongs to the technical field of pollution gas optical remote sensing imaging detection, and particularly relates to a light dilution effect influence resistant sulfur dioxide concentration inversion method. A dual-channel original image is acquired through a dual-channel ultraviolet camera, and the final light intensity of dual channels is calculated by considering a light dilution effect and a camera system error; based on the final light intensity of the two channels, the optical thickness of the two channels and the difference and ratio of the optical thickness of the two channels are calculated; based on the optical thickness difference and the ratio of the two channels, establishing a correlation between the optical thickness difference and the ratio of the two channels and the concentration of SO2 under the conditions of different monitoring distances and different optical thicknesses of aerosol particles, and deducing a calibration spectrogram based on the correlation; and determining the SO2 concentration value matched with the actually measured optical thickness of the aerosol particles according to the actually measured optical thickness of the aerosol particles. The method has the advantages of being high in universality, high in real-time performance, easy to operate and the like, and an effective means is provided for remote sensing monitoring of SO2 gas.

Description

Technical Field

[0001] The invention belongs to the technical field of optical remote sensing imaging detection of polluted gases, and specifically relates to the problem of being affected by the light dilution effect when using a dual-channel SO2 ultraviolet camera to monitor pollution sources at a long distance, and specifically is a sulfur dioxide concentration inversion method that is resistant to the light dilution effect. Background Art

[0002] Sulfur dioxide (SO2) is one of the common pollutants in the atmosphere, and is widely present in a variety of natural and human activities such as volcanic eruptions and industrial emissions. SO2 has a strong pungent odor, and it is easy to catalyze the formation of sulfuric acid mist or sulfate aerosols after contacting particulate matter in the atmosphere. These aerosols not only cause acid rain, but also pose a serious threat to the ecological environment and human health. Therefore, accurate and continuous monitoring of SO2 emissions is of great practical significance for pollution control.

[0003] As a cutting-edge technology, remote sensing technology is widely used in atmospheric pollution source monitoring due to its advantages such as wide detection range, non-contact measurement and dynamic measurement. However, when facing mobile pollution sources, traditional remote sensing technology is difficult to meet the requirements of temporal resolution and spatial resolution due to its complex equipment structure and poor environmental adaptability, which limits its practicality. SO2 ultraviolet camera has the advantages of precise control, wide monitoring range and high enough temporal and spatial resolution, which enables this technology to study the dynamics of pollution source plumes in depth with unprecedented advantages.

[0004] The SO2 UV camera is a dual-channel UV camera based on the atmospheric radiation transmission characteristics. This technology uses the scattering of sunlight as the light source. Based on the Beer-Lambert law and the significant absorption characteristic spectrum of the near-ultraviolet band, the 310nm band is selected as the signal channel to quantify the absorption of SO2 and carbon black particles, and the 330nm band is selected as the reference channel to quantify the absorption of carbon black particles. In order to compare with the national pollutant emission standards, the emission rate of pollutants is usually calculated, and calculating the emission rate requires accurate SO2 concentration data. After the camera collects the pollution source image, the SO2 optical thickness image can be obtained by inversion, and then it is converted into SO2 concentration through precise calibration.

[0005] However, existing calibration methods such as the standard bubble calibration method and the DOAS (Differential Optical Absorption Spectroscopy) calibration method face many challenges in practical applications. The standard bubble calibration method uses multiple "standard bubbles" of known volumes in the laboratory to inject different contents of SO2, and obtains the numerical relationship between optical thickness and concentration by fitting the calibration curve. However, this method does not consider the light dilution effect, so it is only suitable for close-range calibration. Although the DOAS calibration method takes into account the radiation transmission effect and can reduce the impact of the light dilution effect to a certain extent, its reliance on ranging and visibility instruments increases the complexity and cost of the operation, and is limited by the field of view angle, so it can only perform single-point measurements and cannot perform comprehensive calibration of the entire field of view.

[0006] In view of the above problems, the present invention proposes a SO2 inversion method that is resistant to the light dilution effect, aiming to provide a full-field SO2 concentration inversion solution that is easy to operate and highly adaptable. Summary of the invention

[0007] In order to overcome the problems in the prior art, the present invention proposes a sulfur dioxide concentration inversion method that is resistant to the light dilution effect.

[0008] The technical solution of the present invention to solve the above technical problems is as follows:

[0009] The present invention provides a method for inverting sulfur dioxide concentration that is resistant to light dilution effect, comprising the following steps:

[0010] Step 100: acquiring a dual-channel original image through a dual-channel ultraviolet camera, and calculating the final light intensity of the dual channels by taking into account the light dilution effect and the camera system error; wherein the dual channels are a signal channel and a reference channel;

[0011] Step 200: Calculate the optical thickness of the dual channels, the optical thickness difference and ratio of the dual channels based on the final light intensity of the dual channels;

[0012] Step 300: Based on the dual-channel optical thickness difference and ratio, establish the correlation between the dual-channel optical thickness difference and ratio and the SO2 concentration under different monitoring distances and different aerosol particle optical thickness conditions, and derive a calibration spectrum based on the correlation; determine the SO2 concentration value that matches the actually measured aerosol particle optical thickness.

[0013] Furthermore, the dual-channel original image includes: a signal channel plume image of a pollution source, a reference channel plume image of a pollution source, a signal channel sky background image, and a reference channel sky background image.

[0014] Furthermore, the light dilution effect and camera system error are considered to calculate the light intensity of the dual channels, specifically including:

[0015] Considering the scattering effect of aerosol particles in the atmosphere, the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel are obtained;

[0016] Based on the light intensity of the aerosol particles scattered in the pollution source signal channel and the light intensity of the aerosol particles scattered in the pollution source reference channel, and considering the light dilution effect and camera system error, the final light intensity of the pollution source signal channel and the final light intensity of the pollution source reference channel are calculated.

[0017] Furthermore, the scattering effect of aerosol particles in the atmosphere is considered to obtain the light intensity after aerosol scattering in the pollution source signal channel and the light intensity after aerosol scattering in the pollution source reference channel. The specific calculation method is:

[0018]

[0019]

[0020] Among them, L A is the light intensity scattered by aerosol particles in pollution source signal channel A, L B is the light intensity scattered by aerosol particles in pollution source reference channel B; is the sky background light intensity actually measured by signal channel A, is the sky background intensity actually measured by reference channel B; τ m is the optical thickness of aerosol particles; κ A is the atmospheric extinction coefficient of signal channel A, κ B is the atmospheric extinction coefficient of reference channel B; d is the distance from the solar scattered light to the camera from the smoke plume; σ is the absorption cross section of SO2 gas; S is the SO2 column concentration.

[0021] Furthermore, based on the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel, the final light intensity of the pollution source signal channel and the final light intensity of the pollution source reference channel are calculated by taking into account the light dilution effect and the camera system error, and the formula is as follows:

[0022]

[0023]

[0024] in, is the final light intensity of the pollution source signal channel A, is the final light intensity of the pollution source reference channel B, that is; TA (λ) is the transmittance of the filter of signal channel A, T B (λ) is the transmittance of the filter in signal channel B; Q(λ) is the quantum efficiency of the camera.

[0025] Furthermore, it also includes: calculating the sky background light intensity after the signal channel takes into account the light dilution effect and the camera's own influence factors, and the sky background light intensity after the signal channel takes into account the light dilution effect and the camera's own influence factors:

[0026]

[0027]

[0028] in, The sky background light intensity of the signal channel A of the pollution source after considering the light dilution effect and the camera's own influence factors; The sky background light intensity of signal channel B of the pollution source after considering the light dilution effect and the influence of the camera itself.

[0029] Further, the optical thickness of the dual channels is calculated based on the final light intensity of the dual channels, including:

[0030]

[0031]

[0032] Among them, τ A is the optical thickness of signal channel A, is the dark noise of signal channel A; τ B is the optical thickness of reference channel B, is the dark noise of reference channel B.

[0033] Furthermore, in step 200, the optical thickness of the dual channels and the difference and ratio of the optical thickness of the dual channels are calculated, specifically including: performing ratio processing on the difference of the optical thickness of the dual channels and the sum of the optical thickness of the dual channels to obtain the difference and ratio of the optical thickness of the dual channels, and recording the difference and ratio of the optical thickness of the dual channels as parameter C:

[0034]

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] (1) High real-time performance: After the dual-channel ultraviolet camera captures the plume image of the pollution source, the method proposed in the present invention can quickly calculate the correlation between the dual-channel optical thickness difference and ratio and the SO2 concentration. Combined with the real-time acquired aerosol optical thickness, it can efficiently and accurately realize the real-time inversion of SO2 concentration.

[0037] (2) Easy to operate: In the process of pollution source monitoring, the present invention does not require additional rangefinders or visibility measurement equipment. Compared with traditional methods, the system only relies on a dual-channel UV camera and a spectrometer to complete the inversion of SO2 concentration. This greatly simplifies the operation process, reduces the implementation cost and technical complexity of the system, and makes it more operable in various application scenarios.

[0038] (3) Strong universality: This method does not need to measure the distance from the UV camera to the pollution source, and takes into account the scattering effect of aerosol particles in the atmosphere, which can effectively deal with the influence of light dilution effect. Therefore, even in complex aerosol environments or at different monitoring distances, the system can still maintain a high inversion accuracy, ensuring the universality and stability of SO2 concentration monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A flow chart of a SO2 concentration inversion method resistant to light dilution effect proposed by the present invention;

[0041] Figure 2 This is the calibration curve of the traditional calibration method at different particle optical thicknesses and different distances;

[0042] Figure 3 The spectra of the new method at different particle optical thicknesses and different distances;

[0043] Figure 4 This is the SO2 concentration map inverted by the traditional calibration method;

[0044] Figure 5 This is the SO2 concentration map inverted by the new method;

[0045] Figure 6 To read the comparison chart of SO2 concentration in line 400 of the two calibration methods;

[0046] Figure 7 Comparison chart of SO2 concentration in column 500 for reading two calibration methods. DETAILED DESCRIPTION

[0047] In order to further explain the technical means and effects taken by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the technical solutions proposed by the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. The specific features, structures or characteristics in one or more embodiments may be combined in any suitable form. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by technicians in the technical field of the present invention.

[0048] As the monitoring distance increases, the light dilution effect caused by the scattering effect of aerosol particles in the atmosphere will affect the inversion of SO2 concentration. In order to eliminate this effect, it is necessary to calculate the calibration curve for calibration, while the traditional calibration method requires the use of a rangefinder and a visibility measuring instrument, and can only perform single-point measurement, and cannot calibrate the entire field of view of the SO2 ultraviolet camera. To solve this problem, the present invention proposes a SO2 concentration inversion method that does not require distance measurement and can effectively resist the light dilution effect. The following will further explain and illustrate this method in conjunction with the accompanying drawings.

[0049] In one embodiment of the present invention, Figure 1 As shown, a method for inverting sulfur dioxide concentration that is resistant to light dilution effect is provided, comprising the following steps:

[0050] Step 100: acquiring a dual-channel original image through a dual-channel ultraviolet camera, and calculating the light intensity of the dual channels by taking into account the light dilution effect and the camera system error; wherein the dual channels are a signal channel and a reference channel;

[0051] Step 200: Calculate the optical thickness of the dual channels and the difference and ratio of the optical thickness of the dual channels based on the light intensity of the dual channels;

[0052] Step 300: Based on the dual-channel optical thickness difference and ratio, establish the correlation between the dual-channel optical thickness difference and ratio and the SO2 concentration under different monitoring distances and different aerosol particle optical thickness conditions, and derive a calibration spectrum based on the correlation; determine the SO2 concentration value that matches the actually measured aerosol particle optical thickness.

[0053] The following is a detailed explanation of each of the above steps:

[0054] Step 100: Acquire a dual-channel original image through a dual-channel ultraviolet camera, and calculate the light intensity of the dual channels by taking into account the light dilution effect and the camera system error; wherein the dual channels are a signal channel and a reference channel.

[0055] As an example, this step may include the following sub-steps:

[0056] Step 110: Use the dual-channel structure of the SO2 ultraviolet camera to simultaneously capture original images to obtain a dual-channel original image, wherein the dual-channel original image includes a signal channel image and a reference channel image.

[0057] The SO2 ultraviolet camera of this embodiment is composed of two ultraviolet lenses with the same indicators, two back-illuminated high-sensitivity ultraviolet CCD cameras with the same indicators, and two ultraviolet bandpass filters with central wavelengths of 310nm (first filter) and 330nm (second filter). Among them, the back-illuminated high-sensitivity ultraviolet CCD camera, the first filter, and the ultraviolet lens are coaxially connected in sequence to form a signal channel; the ultraviolet back-illuminated high-sensitivity CCD camera, the second filter, and the ultraviolet lens are coaxially connected in sequence to form a reference channel. The signal channel and the reference channel constitute the dual-channel structure of the SO2 ultraviolet camera. Through the design of the dual-channel structure, the spectral interference of coexisting substances such as carbon black particles can be effectively suppressed, and the negative impact of carbon black particles on SO2 concentration inversion can be significantly weakened, thereby achieving accurate quantification of SO2 concentration.

[0058] When collecting emission images of pollution sources, the two channels will work simultaneously, so that the images of the signal channel and the reference channel will correspond one to one. The signal channel and the reference channel are used to image the pollution source plume, and the signal channel plume image of the pollution source and the reference channel plume image of the pollution source are obtained respectively. After that, the dual-channel original images collected by the dual-channel SO2 ultraviolet camera are read, that is, the signal channel plume image of the pollution source and the reference channel plume image of the pollution source.

[0059] It is also necessary to collect two channels of sky background images at the current moment. When collecting the sky background, just point the UV camera at a clean area in the sky without smoke plume interference to shoot.

[0060] Step 120: Based on the acquired dual-channel original image, taking into account the scattering effect of aerosol particles in the atmosphere, the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel are obtained;

[0061] When the solar scattering signal passes through the plume emitted by the pollution source, the SO2 gas has a significant absorption characteristic in the near-ultraviolet spectral region, causing the transmitted light intensity to show a significant wavelength-dependent attenuation phenomenon. According to the Beer-Lambert law, when there is an absorbing gas plume in the radiation propagation path, the amount of radiation absorbed by the gas can be quantified:

[0062] I A =I′ A ·exp[-τ′ A ];

[0063] I B =I B′·exp[-τ′ B ];

[0064] τ′ A =σ·S+τ p ;

[0065] τ′ B =τ p ;

[0066] Among them, I A I is the intensity of solar radiation from signal channel A after passing through the smoke plume; B is the intensity of solar radiation from reference channel B after passing through the smoke plume; I′ A is the sky background intensity of signal channel A, i.e., the intensity before the radiation passes through the smoke plume; I′ is the sky background intensity of reference channel B, i.e., the intensity before the radiation passes through the smoke plume; σ is the absorption cross section of SO2 gas; S is the SO2 column concentration; τ p is the particle optical thickness; τ′ A is the optical thickness of the original signal channel A; τ′ B is the optical thickness of the original reference channel B.

[0067] Under ideal conditions, the SO2 optical thickness can be obtained by calculating the difference between the optical thickness of the signal channel and the optical thickness of the reference channel. The SO2 optical thickness can then be converted into SO2 concentration using the calibration curve, thereby achieving high-precision detection of the spatial distribution of SO2 gas pollutants and their temporal evolution. However, in actual long-distance monitoring applications, aerosol particles in the atmosphere will significantly affect the scattering characteristics of sunlight. When the scattered light passes through the plume, a portion of the photons will be scattered out of the instrument's field of view by the aerosol particles; at the same time, some photons that have not passed through the plume will also be scattered into the instrument's field of view. This scattering effect will cause the actual measured value of the light intensity to deviate from the theoretically predicted value, thereby inducing a light dilution effect. Assuming that only one scattering occurs, the resulting radiation increment and the light intensity reaching the instrument can be expressed by the following expressions:

[0068]

[0069]

[0070] Among them, L A is the light intensity scattered by aerosol particles in pollution source signal channel A, L B is the light intensity scattered by aerosol particles in pollution source reference channel B; is the sky background light intensity actually measured by signal channel A, is the sky background intensity actually measured by reference channel B; τ m is the optical thickness of aerosol particles; κ A is the atmospheric extinction coefficient of signal channel A, κB is the atmospheric extinction coefficient of reference channel B; d is the distance from the sun’s scattered light to the camera from the plume.

[0071] Step 130: Based on the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel, taking into account the light dilution effect and camera system error, calculate the final light intensity of the pollution source signal channel and the final light intensity of the pollution source reference channel.

[0072] In addition to the scattering effect of aerosols in the atmosphere that will affect the light intensity measurement results, the camera itself will also introduce additional interference in the process of receiving light signals. These interferences mainly come from the hardware characteristics of the camera, such as incident radiation rate, filter transmittance and quantum efficiency, etc. These factors may further affect the final measurement accuracy, so they need to be considered in the light intensity calculation. The formula is as follows:

[0073]

[0074]

[0075] in, The light intensity of the pollution source signal channel A after considering the light dilution effect and the camera's own influence factors, that is, the final light intensity of the pollution source signal channel A; is the light intensity of the pollution source reference channel B after considering the light dilution effect and the camera's own influence factors, and the final light intensity of the pollution source reference channel B; T A (λ) is the transmittance of the filter in signal channel A, T B (λ) is the transmittance of the filter in signal channel B; Q(λ) is the quantum efficiency of the camera.

[0076] It also includes: calculating the sky background light intensity after the signal channel takes into account the light dilution effect and the camera's own influence factors, and the sky background light intensity after the signal channel takes into account the light dilution effect and the camera's own influence factors:

[0077]

[0078]

[0079] The sky background light intensity of signal channel A after considering the light dilution effect and the camera's own influence factors; The sky background light intensity for signal channel B after taking into account the light dilution effect and the camera's own influence factors.

[0080] Step 200: Based on the final light intensity of the dual channels, the optical thickness of the dual channels, the difference of the optical thickness of the dual channels, and the sum of the optical thickness of the dual channels are calculated, and the difference of the optical thickness of the dual channels is processed by ratio with the sum of the optical thickness of the dual channels to obtain the difference and ratio of the optical thickness of the dual channels, and the difference and ratio of the optical thickness of the dual channels is recorded as parameter C.

[0081] Based on the final light intensity of the dual channels, that is, based on the calculated light intensity of signal channel A and reference channel B after considering the light dilution effect and the camera's own influencing factors, the optical thickness of signal channel A and reference channel B can be further determined by using the ratio of the light intensity before and after passing through the smoke plume. In order to improve the accuracy of the measurement, the dark noise signal generated by the sensor needs to be subtracted during the calculation process to improve the signal-to-noise ratio. This noise signal will still be generated when no light enters the camera, which has a direct impact on the measurement accuracy. After completing the noise correction, signal channel A can effectively obtain the absorption information of SO2 gas and carbon black particles, and its optical thickness expression is:

[0082]

[0083] Among them, τ A is the optical thickness of signal channel A, is the dark noise of signal channel A.

[0084] The reference channel B is only used to obtain the information of carbon black particles, and its optical thickness expression is:

[0085]

[0086] Among them, τ B is the optical thickness of reference channel B, is the dark noise of reference channel B.

[0087] The difference of the dual-channel optical thickness is processed with the sum of the dual-channel optical thickness to obtain the dual-channel optical thickness difference and ratio, and the dual-channel optical thickness difference and ratio is recorded as parameter C:

[0088]

[0089] Step 300: Based on the dual-channel optical thickness difference and ratio, establish the correlation between the dual-channel optical thickness difference and ratio and the SO2 concentration under different monitoring distances and different aerosol particle optical thickness conditions, and derive a calibration spectrum based on the correlation; determine the SO2 concentration value that matches the actually measured aerosol particle optical thickness.

[0090] By inputting different monitoring distances and corresponding aerosol particle optical thickness, a relationship diagram between parameter C and SO2 concentration is constructed. This relationship diagram details the changing trend between aerosol optical thickness and SO2 concentration under different atmospheric conditions. Based on this relationship diagram, a calibrated spectrum diagram is further derived. In the actual inversion of SO2 concentration, the corresponding SO2 concentration can be quickly and accurately determined based on the real-time acquired aerosol particle optical thickness combined with the above derived spectrum diagram.

[0091] Specifically, through parameter C, combined with the optical thickness information of signal channel A and reference channel B, wavelength-independent interferences such as light dilution effect can be effectively removed. Since the light dilution effect is relatively consistent in different wavelength ranges, the optical thickness of channels A and B will be similarly affected. By calculating the difference in optical thickness between signal channel A and reference channel B, the interference of the common effect can be eliminated, thereby extracting the effective signal directly related to the change in SO2 concentration. In addition, parameter C does not depend on the absolute value of light intensity. The signals of the two channels are normalized by ratio, eliminating signal intensity fluctuations caused by changes in monitoring distance, visibility or background light intensity, and indirectly eliminating various influences through relative changes between signal channel A and reference channel B, thereby more accurately reflecting the actual changes in SO2 concentration. This makes it possible to accurately establish the relationship between parameter C and SO2 concentration under different monitoring distances and optical thickness conditions of aerosol particles. Based on this correlation, a calibration spectrum can be further derived. In the actual inversion process, the measured optical thickness of the aerosol particles can be combined with the pre-established calibration spectrum to determine the SO2 concentration value that matches the aerosol conditions, thereby achieving accurate inversion of pollutant concentrations corrected for light dilution effects.

[0092] Case implementation and validation experiment results

[0093] In step 300, two methods are used to perform simulation experiments under different aerosol particle optical thicknesses and different distance conditions. Figure 2 As shown in the calibration curve using the traditional calibration method, when the distance between the camera and the smoke plume is 0 km, there is an approximately linear relationship between the SO2 optical depth and the SO2 concentration, and the calibration curve is less affected by the optical depth of aerosol particles; however, Figure 2(b), (c), (d), as the distance increases, the relationship gradually turns into a nonlinear relationship, which indicates that the effect of distance on the inversion of SO2 concentration is nonlinear. Under the same aerosol particle optical thickness conditions, the maximum effect of distance on the calibration curve can reach about 93%. In addition, the optical thickness of aerosol particles is also a key factor affecting the inversion of SO2 concentration. At the same distance, aerosol particles can cause the maximum deviation of the calibration curve to be about 68%. The increase in its optical thickness will aggravate the extinction effect, making the inverted SO2 concentration higher, thereby changing the slope of the calibration curve. Therefore, both the distance between the camera and the smoke plume and the aerosol particles will affect the measurement results of the traditional SO2 UV camera inversion method.

[0094] And use the calibration spectrum diagram of the present invention, such as Figure 3 As shown, it can be seen that under different distances and the same aerosol particle optical thickness conditions, the color gradient change amplitude of the calibration spectrum of the present invention is small, indicating that no matter at a close distance (0km) or a long distance (15km), the SO2 concentration inversion result has no significant nonlinear deviation. At the same time, the calibration spectra of 0km and 15km, under the condition of the maximum optical thickness of aerosol particles, have a difference of only about 21%, which is about 77% higher than the error influence of the traditional calibration method, showing that the method has strong distance adaptability. In addition, at the same distance, the conditions of different aerosol optical thickness have less impact on the new method. The maximum difference of the calibration spectrum of 15km is only 46%, which is about 32% higher than the DOAS calibration method, reflecting the high resistance of the new method to aerosol interference.

[0095] In order to further verify the reliability in practical applications, the study used the actual collected industrial chimney emission data, and applied two methods to invert the SO2 concentration and conduct comparative analysis. Figure 4 The SO2 concentration image obtained by inversion using the traditional calibration method is shown. Figure 5 The SO2 concentration image inverted by the new method of the present invention is shown. By comparison, it can be seen that the SO2 concentration images calculated by the two methods have certain similarities in the plume area, while in the non-plume area, the concentration image inverted by the traditional calibration method has a higher SO2 concentration, while the SO2 concentration distribution inverted by the present invention is more uniform and reasonable. This shows that the new method is not only comparable to the traditional calibration method, but also provides more reliable results to a certain extent, and has scientific feasibility. In order to further prove the feasibility and accuracy of the present invention, the two methods are respectively compared in the 400th column (such as Figure 6 ) and line 500 (as Figure 7The results show that the inversion concentrations of the two methods are almost the same when passing through the plume area; however, in the area without passing through the plume, the inversion concentration of the new calibration method is lower and more in line with the actual situation. This shows that the new method proposed in the present invention has a stronger anti-interference ability in inverting concentration, and effectively avoids the problem of overestimation of concentration caused by local optical interference.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such 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, and should be included in the protection scope of the present invention.

Claims

1. A method for inverting sulfur dioxide concentration that is resistant to light dilution effect, characterized in that: The following steps are involved: Step 100: acquiring a dual-channel original image through a dual-channel ultraviolet camera, and calculating the final light intensity of the dual channels by taking into account the light dilution effect and the camera system error; wherein the dual channels are a signal channel and a reference channel; Step 200: Calculate the optical thickness of the dual channels and the difference and ratio of the optical thickness of the dual channels based on the final light intensity of the dual channels; Step 300: Based on the dual-channel optical thickness difference and ratio, establish the correlation between the dual-channel optical thickness difference and ratio and the SO2 concentration under different monitoring distances and different aerosol particle optical thickness conditions, and derive a calibration spectrum based on the correlation; determine the SO2 concentration value that matches the actually measured aerosol particle optical thickness.

2. The method for inverting sulfur dioxide concentration that is resistant to light dilution effect according to claim 1, characterized in that: The dual-channel original image includes: a signal channel plume image of a pollution source, a reference channel plume image of a pollution source, a signal channel sky background image, and a reference channel sky background image.

3. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 1, characterized in that: The light dilution effect and camera system error are considered to calculate the light intensity of the dual channels, specifically including: Considering the scattering effect of aerosol particles in the atmosphere, the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel are obtained; Based on the light intensity of the aerosol particles scattered in the pollution source signal channel and the light intensity of the aerosol particles scattered in the pollution source reference channel, and considering the light dilution effect and camera system error, the final light intensity of the pollution source signal channel and the final light intensity of the pollution source reference channel are calculated.

4. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 3, characterized in that: The scattering effect of aerosol particles in the atmosphere is considered to obtain the light intensity after aerosol scattering in the pollution source signal channel and the light intensity after aerosol scattering in the pollution source reference channel. The specific calculation method is: Among them, L A is the light intensity scattered by aerosol particles in pollution source signal channel A, L B The light intensity after scattering by aerosol particles is considered for the pollution source reference channel B; is the sky background light intensity actually measured by signal channel A, is the sky background intensity actually measured by reference channel B; τ m is the optical thickness of aerosol particles; κ A is the atmospheric extinction coefficient of signal channel A, κ B is the atmospheric extinction coefficient of reference channel B; d is the distance from the solar scattered light to the camera from the smoke plume; σ is the absorption cross section of SO2 gas; S is the SO2 column concentration.

5. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 4, characterized in that: Based on the light intensity after scattering of aerosol particles in the pollution source signal channel and the light intensity after scattering of aerosol particles in the pollution source reference channel, the final light intensity of the pollution source signal channel and the final light intensity of the pollution source reference channel are calculated by taking into account the light dilution effect and the camera system error. The formula is as follows: in, is the final light intensity of the pollution source signal channel A; is the final light intensity of the pollution source reference channel B; T A (λ) is the transmittance of the filter in signal channel A, T B (λ) is the transmittance of the filter in signal channel B; Q(λ) is the quantum efficiency of the camera.

6. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 5, characterized in that: Also includes: The sky background light intensity after the signal channel considers the light dilution effect and the camera's own influence factors is calculated: in, The sky background light intensity of the signal channel A of the pollution source after considering the light dilution effect and the camera's own influence factors; The sky background light intensity of signal channel B of the pollution source after considering the light dilution effect and the influence of the camera itself.

7. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 6, characterized in that: The method of calculating the optical thickness of the dual channels based on the final light intensity of the dual channels includes: Among them, τ A is the optical thickness of signal channel A, is the dark noise of signal channel A; τ B is the optical thickness of reference channel B, is the dark noise of reference channel B.

8. The method for inverting sulfur dioxide concentration resistant to light dilution effect according to claim 7, characterized in that: In step 200, the optical thickness of the dual channels and the difference and ratio of the optical thickness of the dual channels are calculated, which specifically includes: performing ratio processing on the difference of the optical thickness of the dual channels and the sum of the optical thickness of the dual channels to obtain the difference and ratio of the optical thickness of the dual channels, and recording the difference and ratio of the optical thickness of the dual channels as parameter C:

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