A Method for Detecting and Inverting the Extinction Coefficient of Aerosols under Clouds by Lidar

Abstract

A method for detecting and inverting the aerosol extinction coefficient of a cloud by a lidar, comprising obtaining the aerosol extinction coefficient corresponding to the echo signal of the lidar in the horizontal direction as a first calibration value EXT I ; Determine the altitude of the calibration point at the cloud base according to the distance correction square signal at the set time, and obtain the atmospheric extinction coefficient corresponding to the altitude of the calibration point at the cloud base, which is used as the second calibration value EXT0; Based on the second calibration value EXT0, obtain the second extinction coefficient profile, and obtain the extinction coefficient at the first height X according to the second extinction coefficient profile, and use it as the second calibration variable value EXT X ;|EXT X ‑EXT I |>EXT I When EXT0 is equal to δ, the second calibration value EXT0 is adjusted, and the above step of obtaining the second extinction coefficient profile is returned to based on the adjusted second calibration value EXT0 until EXT0 is equal to δ. X ‑EXT I |<EXT I ·δ, output the second calibration variable value EXT X , where δ is the relative error. The invention is based on the fact that this method can accurately invert the aerosol extinction coefficient even in the presence of clouds.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radars, and in particular relates to a laser radar detection and inversion method for sub-cloud aerosol extinction coefficients. Background Art

[0002] LiDAR can not only monitor the intensity changes of atmospheric aerosols, but also observe the vertical distribution of atmospheric aerosols, and perform quantitative analysis after inverting the observation results.

[0003] When performing vertical detection, lidar often uses the Fernald method to invert the atmospheric aerosol extinction coefficient. This requires finding an altitude with low atmospheric aerosol content as a reference point and then using Fernald backward integration to obtain the vertical profile of the aerosol extinction. However, when there are low, thick clouds in the sky, the lidar return signal first increases sharply, then decreases, eventually approaching background noise. In this case, the laser cannot penetrate the cloud layer, making it impossible to determine the reference point altitude required for inversion, thus making it difficult to invert the aerosol below the cloud. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a method for detecting and inverting the aerosol extinction coefficient under clouds using a lidar. The specific technical solution is as follows:

[0005] A method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar, comprising:

[0006] Obtain the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction as the first calibration value EXT I ; Determine the height of the calibration point at the cloud base according to the distance correction square signal at the set time, and obtain the atmospheric extinction coefficient corresponding to the height of the calibration point at the cloud base, which is used as the second calibration value EXT0;

[0007] Based on the second calibration value EXT0, a second extinction coefficient profile is obtained, and the extinction coefficient at the first height X is obtained according to the second extinction coefficient profile, and is used as the second calibration variable value EXT X ; The first height X is greater than the blind spot height;

[0008] Compare the first calibration value EXT I and the second calibration variable value EXT X ,|EXT X -EXT I |>EXT I When EXT0 is equal to δ, the second calibration value EXT0 is adjusted, and the above step of obtaining the second extinction coefficient profile is returned to based on the adjusted second calibration value EXT0 until EXT0 is equal to δ. X -EXT I |<EXTI ·δ, output the second calibration variable value EXT X , where δ is the relative error.

[0009] The inversion method of the aerosol extinction coefficient under clouds as described above, further comprising obtaining the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction, comprising: obtaining the aerosol extinction coefficient of the laser radar echo signal in the horizontal direction by using a slope method.

[0010] The above-mentioned inversion method of the aerosol extinction coefficient under the cloud further uses the slope method to obtain the aerosol extinction coefficient of the lidar echo signal in the horizontal direction as the first calibration value EXT I ,include:

[0011] Assuming that the atmosphere is horizontally uniform, the atmospheric backscatter echo signal power P(Y) received by the lidar at a horizontal distance Y is:

[0012] P(Y)=P t kY -2 β H exp(-2α H Y) (2)

[0013] Where P t is the laser emission power (W), k is the radar system constant (W·km 3 ·Sr), β H is the horizontal atmospheric backscatter coefficient (km -1 Sr -1 ), α H Indicates the horizontal atmospheric extinction coefficient (km -1 );

[0014] Multiply both sides of formula (2) by the square of the distance, take the logarithm and take the derivative to obtain:

[0015]

[0016] Under the condition of uniform atmospheric level, dβ H / dY=0; then:

[0017]

[0018] For ln[P(Y)Y 2 ] and Y are fitted by the least square method, and half of its slope is the horizontal atmospheric extinction coefficient α H , α H As the first calibration value EXT I .

[0019] The inversion method of the subcloud aerosol extinction coefficient as described above, further, obtaining the second extinction coefficient profile based on the second calibration value EXT0, includes obtaining the second extinction coefficient profile based on the second calibration value EXT0 using the Fernald backward integration method.

[0020] As described above, the inversion method of the subcloud aerosol extinction coefficient further includes that the value range of the horizontal distance Y received by the lidar is 0.06-1 km.

[0021] In the above-mentioned inversion method for the subcloud aerosol extinction coefficient, further, the first height X is greater than the blind spot height. Specifically, the first height X has a value range of 0.06-1 km.

[0022] The above-mentioned inversion method of the subcloud aerosol extinction coefficient, further comprising: adjusting the second calibration value EXT0;

[0023] The ratio of the laser radar echo signal to the molecular signal R(Z C ) Increase the iteration step value to update the ratio of the laser radar echo signal to the molecular signal R(Z C ) target value, based on the ratio of the laser radar echo signal to the molecular signal R(Z C ) The target value obtains the corresponding backscattering coefficient β α (Z C ), using the aerosol extinction backscattering ratio formula S a Get the aerosol extinction coefficient boundary value α a (Z c ), the aerosol extinction coefficient boundary value α a (Z c ) is the atmospheric extinction coefficient corresponding to the calibration point height at the cloud base, which serves as the second calibration value EXT0 corresponding to the target value.

[0024] In the above-mentioned inversion method for the subcloud aerosol extinction coefficient, further, the iteration step value ranges from 0.01 to 0.5.

[0025] The above-mentioned inversion method of the aerosol extinction coefficient under the cloud, further, the ratio of the laser radar echo signal to the molecular signal R (Z C ) has an initial value of 1.01.

[0026] In the above-mentioned inversion method for the subcloud aerosol extinction coefficient, further, the relative error δ has a value range of 0.01-0.05.

[0027] The advantages of the present invention are:

[0028] (1) The method described in this application does not rely on an absolutely accurate calibration altitude; it only needs to be within a certain range to obtain the inversion results of the aerosol below the cloud. The extinction coefficient color map generated based on the method described in this application can clearly invert the position of the cloud layer and the distribution of aerosol below the cloud, indicating that the method described in this application can accurately invert the aerosol extinction coefficient even in the presence of clouds.

[0029] (2) In this application, the calibration height remains unchanged during each iteration, and the ratio of the laser radar echo signal to the molecular signal R (Z C ) and continuously iterate to achieve the goal of getting closer to the true value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention provides a flow chart of a method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar.

[0031] Figure 2 This is a graph showing the relationship between the range correction signal and altitude at 11:30 a.m. (local time) on April 9, 2024.

[0032] Figure 3 The present invention is a flowchart of a method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar in one embodiment of the present invention.

[0033] Figure 4 The upper middle part is a color map of the extinction coefficient obtained by inverting the portable infrared lidar echo signal using the traditional Fernald backward integration method, and the lower part is a color map of the extinction coefficient obtained by inverting the portable infrared lidar signal using this method.

[0034] Figure 5 Comparison diagram of lidar echo signals obtained by traditional Fernald backward integration method and this method.

[0035] Figure 6 is the average relative error of this method at different heights. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In the description of the embodiments of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0037] When LiDAR is used for vertical detection, it is usually necessary to use the Fernald method to invert the atmospheric aerosol extinction coefficient. The extinction coefficient can be used to quantitatively analyze the aerosol content. If the calibration point height Z is known, C The extinction coefficient of aerosol and air molecules at , according to Fernald backward integration formula (see formula 1), if we want to obtain the atmospheric aerosol extinction coefficient α based on the lidar echo signal a (Z), four parameters need to be determined, namely aerosol extinction backscattering ratio S a , air molecule extinction backscattering ratio S m , the extinction coefficient α of air molecules m (Z), calibration point height Z C The aerosol extinction coefficient α at a (Z c ).

[0038] The aerosol extinction backscattering ratio S a =α a (Z) / β a (Z) is usually between 10 and 90 Sr. Air molecule extinction backscattering ratio S m Usually a constant, i.e. S m =8π / 3. Extinction coefficient of air molecules α m (Z) is usually obtained from the US Standard Atmosphere Model. Usually the first three parameters are easier to determine. C The aerosol extinction coefficient α at a (Z c ) It is usually difficult to get the exact value. The selection of the calibration point height usually needs to be determined by a clean atmosphere. Calculate the calibration point height Z C It is usually calculated by the ratio of the laser radar range correction signal to the molecular backscatter coefficient (P(Z)·Z 2 / β m) is obtained. And the calibration point height Z C The boundary value of atmospheric aerosol extinction coefficient is usually an empirical value, which is 1+β a (Z c ) / β m (Z c )=1.01 to inversely deduce the atmospheric aerosol backscattering coefficient β at the calibration point height a (Z c ) is obtained.

[0039]

[0040] Where P(Z) is the power (W) of the atmospheric scattered echo signal received by the lidar at distance Z.

[0041] After analysis, when there are low and thick clouds in the sky, the lidar echo signal first increases sharply and then decreases, and finally tends to background noise. This signal trend indicates that the laser does not penetrate the cloud layer, which makes it challenging to determine the calibration height required for the inversion. Therefore, this introduces a significant error in the inversion of the aerosol extinction coefficient under the clouds. Due to the inability to determine the height of the calibration point, it is impossible to invert the true atmospheric aerosol extinction coefficient using only the Fernald method. In this context, if Figure 1 As shown, the present application discloses a method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar, comprising:

[0042] Obtain the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction as the first calibration value EXT I ; Determine the height of the calibration point at the cloud base according to the distance correction square signal at the set time, and obtain the atmospheric extinction coefficient corresponding to the height of the calibration point at the cloud base, which is used as the second calibration value EXT0;

[0043] Based on the second calibration value EXT0, a second extinction coefficient profile is obtained, and the extinction coefficient at the first height X is obtained according to the second extinction coefficient profile, and is used as the second calibration variable value EXT X ; The first height X is greater than the blind spot height;

[0044] Compare the first calibration value EXT I and the second calibration variable value EXT X ,|EXT X -EXT I |>EXT I When EXT0 is equal to δ, the second calibration value EXT0 is adjusted, and the above step of obtaining the second extinction coefficient profile is returned to based on the adjusted second calibration value EXT0 until EXT0 is equal to δ. X -EXT I |<EXT I·δ, output the second calibration variable value EXT X , where δ is the relative error.

[0045] In one embodiment, obtaining the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction includes: obtaining the aerosol extinction coefficient of the laser radar echo signal in the horizontal direction using a slope method.

[0046] In detail, assuming that the atmosphere is horizontally uniform, the atmospheric backscatter echo signal power P(Y) received by the lidar at a horizontal distance Y is:

[0047] P(Y)=P t kY -2 β H exp(-2α H Y) (2)

[0048] Where P t is the laser emission power (W), k is the radar system constant (W·km 3 ·Sr), β H is the horizontal atmospheric backscatter coefficient (km -1 Sr -1 ), α H Indicates the horizontal atmospheric extinction coefficient (km -1 ).

[0049] Multiply both sides of formula (2) by the square of the distance, take the logarithm and take the derivative to obtain:

[0050]

[0051] Under the condition of uniform atmospheric level, dβ H / dY=0. Then:

[0052]

[0053] For ln[P(Y)Y 2 ] and Y are fitted by the least square method, and half of its slope is the horizontal atmospheric extinction coefficient α H , α H As the first calibration value EXT I In order to obtain more accurate parameters, the value range of Y is 0.06-0.09km; because the extinction coefficient of air molecules near the ground is one order of magnitude smaller than that of atmospheric aerosols, it can also be considered that α H The atmospheric aerosol extinction coefficient will not cause too much error.

[0054] In one embodiment, the height of the calibration point at the cloud bottom is determined based on the distance correction square signal at a set time, such as Figure 2The figure shows the relationship between the distance-corrected signals obtained during experimental observations. The squared distance-corrected signal at a given moment is used to determine the altitude of the calibration point at cloud base, which is approximately 1 km. In the presence of thick clouds, the lidar cannot penetrate the cloud layer, meaning it cannot detect significant atmospheric echo signals above the clouds. Therefore, the "clean air" altitude used in the traditional Fernald method cannot be used to determine the altitude of the calibration point required for the inversion. To invert the aerosol extinction coefficient below the clouds, this method uses a cloud base altitude of approximately 1.35-1.4 km as the calibration point.

[0055] The atmospheric extinction coefficient corresponding to the calibration point height at the bottom is obtained as the second calibration value EXT0. Specifically, the calibration point height Z C Select the height of the clean atmosphere with almost no atmospheric aerosols and calculate the calibration point height Z C The ratio of the laser radar echo signal to the molecular signal R(Z C ) is determined by the minimum value of. Calibration point height Z C The backscatter coefficient β α (Z C ) is usually selected by R(Z C ) empirical value, the initial value is 1.01, and the initial calculation uses 1.01 as the ratio of the laser radar echo signal to the molecular signal R(Z C ) target value, given by Inversely calculate the height Z of the calibration point C The atmospheric extinction coefficient β α (Z C ), where the height of the calibration point Z C The molecular backscattering coefficient β m (Z C ), given by the US Standard Atmosphere Model (which can be understood as a known value). According to the inverse backscatter coefficient β α (Z C ), and then use the aerosol extinction backscattering ratio formula S a Get the aerosol extinction coefficient boundary value α a (Z c ), the aerosol extinction coefficient α a (Z c ) The boundary value is the atmospheric extinction coefficient corresponding to the calibration point height at the cloud bottom, which is used as the second calibration value EXT0. The aerosol extinction backscattering ratio formula S corresponding to lasers of different wavelengths is: a The values between 10 and 90 Sr are different. For example, the aerosol extinction backscattering ratio formula for a laser with a wavelength of 1064 nm is S a The value is 40. Therefore, after determining the laser wavelength, the aerosol extinction backscattering ratio formula Sa The value of is determined, which can be realized by inferring the backscattering coefficient β α (Z C ), and then use the aerosol extinction backscattering ratio formula S a Get the aerosol extinction coefficient boundary value α a (Z c ).

[0056] In one embodiment, obtaining the second extinction coefficient profile based on the second calibration value EXT0 includes obtaining the second extinction coefficient profile using a Fernald backward integration method based on the second calibration value EXT0.

[0057] The first height X is greater than the blind spot height. Specifically, the first height X is in the range of 0.06-0.08 km. The first height X can be any one of 0.06 km, 0.065 km, 0.068 km, 0.070 km, 0.072 km, 0.075 km, 0.078 km, and 0.080 km. The extinction coefficient at the first height X is obtained according to the second extinction coefficient profile and used as the second calibration variable value EXT X When the first height X is 0.06 km, the second calibration variable value is EXT 60 When the first height X is 0.07 km, the second calibration variable value is EXT 70 , and so on for other heights.

[0058] Adjusting the second calibration value EXT0 includes:

[0059] The ratio of the laser radar echo signal to the molecular signal R(Z C ) Increase the iteration step value to update the ratio of the laser radar echo signal to the molecular signal R(Z C ) target value, based on the ratio of the laser radar echo signal to the molecular signal R(Z C ) The target value obtains the corresponding backscattering coefficient β α (Z C ), using the aerosol extinction backscattering ratio formula S a Get the aerosol extinction coefficient boundary value α a (Z c ), the aerosol extinction coefficient boundary value α a (Z c ) is the atmospheric extinction coefficient corresponding to the calibration point height at the cloud base, which serves as the second calibration value EXT0 corresponding to the target value.

[0060] In one embodiment, the iteration step value ranges from 0.01 to 0.5, and the smaller the iteration step value, the more accurate the measured data.

[0061] In one embodiment, the relative error δ is in the range of 0.01-0.05. The smaller the relative error is, the more accurate the measured data is.

[0062] like Figure 2 As shown, with Y = 0.07, S a =40, X = 0.07, δ = 0.01, the iteration step is 0.01, the relative error δ is 0.01, a method for detecting and retrieving the aerosol extinction coefficient under clouds by lidar is included.

[0063] The slope method is used to obtain the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction as the first calibration value EXT I ; The relationship between the distance correction signals obtained when observing at 11:30 on April 9, 2024. Figure 3 As shown, the calibrated height of the cloud base is 1 km. According to R(Z C ) has an initial value of 1.01, and the calibration point height Z C The molecular backscattering coefficient β m (Z C ) is known, the atmospheric extinction coefficient β corresponding to the calibration point height at the cloud base is obtained α (Z C ), which serves as the second calibration value EXT0;

[0064] Based on the second calibration value EXT0, a second extinction coefficient profile is obtained, and the extinction coefficient at the first height of 0.07 km is obtained according to the second extinction coefficient profile, and used as the second calibration variable value EXT 70 ;

[0065] Compare the first calibration value EXT I and the second calibration variable value EXT 70 ,|EXT 70 -EXT I |>EXT I 0.01, R(Z C ) is based on the iteration step size, the value is 1.02, based on the calibration point height Z C The molecular backscattering coefficient β m (Z C ) is known, the atmospheric extinction coefficient β corresponding to the calibration point height at the cloud base is retrieved α (Z C ), which is used as the adjusted second calibration value EXT0, and based on the adjusted second calibration value EXT0, the above step of obtaining the second extinction coefficient profile is returned to be executed until |EXT 70 -EXT I |<EXTI 0.01, output the second calibration variable value EXT X , thereby obtaining the corresponding second extinction coefficient profile. 70 -EXT I |<EXT I · Before 0.01, R(Z C ) increases the iteration step size based on the last value, R(Z C ) values are 1.01, 1.02, 1.03, etc.

[0066] Compared with the traditional Fernald backward integration, this method can clearly invert the specific details of the extinction coefficient under clouds. Figure 4 The upper middle part is a color map of the extinction coefficient obtained by inverting the echo signal of the portable infrared lidar using the traditional Fernald backward integration method. Figure 4 The lower middle part is the extinction coefficient color map obtained by inverting the portable infrared lidar signal using this method. From these two pictures, it can be seen that the traditional Fernald backward integration method cannot clearly invert the position of the clouds, and there are "blanks" in the aerosol extinction coefficient part under the clouds, which contains negative values. This shows that the traditional Fernald method is significantly affected by the cloud cover and cannot accurately calibrate the portable infrared lidar echo signal, resulting in certain errors. However, the extinction coefficient color map obtained based on the method of the present application can clearly invert the position of the cloud layer and the distribution of aerosols under the clouds. It can be clearly seen that the processing results of this method for the distribution of clouds and aerosols under the clouds are better than those of the traditional Fernald method. The method described in this application can accurately invert the aerosol extinction coefficient even in the presence of clouds.

[0067] Regarding the accuracy of the verification algorithm, such as Figure 5 As shown in the figure, the laser radar echo signal at a certain moment of the high-energy radar is selected and processed by the traditional Fernald backward integration and the method proposed in this paper. The comparison shows that the two methods are not much different. Figure 6 It can be seen that the maximum error of the results obtained by this method relative to the standard value is about 6.5%, and the average relative error is less than 5%. Therefore, it can be concluded that the inversion results of this method are relatively accurate.

[0068] Throughout this specification, references to terms such as "some embodiments" or "examples" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments. Furthermore, those skilled in the art may combine and integrate different embodiments or examples described in this specification.

[0069] The above description is merely a preferred embodiment of the present invention and does not limit the present invention in any way. Any person skilled in the art who, without departing from the scope of the present invention, makes any equivalent substitution, modification, or other changes to the technical solution and technical content disclosed in the present invention shall be deemed to be within the scope of the present invention and still fall within the scope of protection of the present invention.

Claims

1. A method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar, characterized in that: include: Obtain the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction as the first calibration value EXT I ; Determine the height of the calibration point at the cloud base according to the distance correction square signal at the set time, and obtain the atmospheric extinction coefficient corresponding to the height of the calibration point at the cloud base, which is used as the second calibration value EXT0; Based on the second calibration value EXT0, a second extinction coefficient profile is obtained, and the extinction coefficient at the first height X is obtained according to the second extinction coefficient profile, and is used as the second calibration variable value EXT X ; The first height X is greater than the blind spot height; Compare the first calibration value EXT I and the second calibration variable value EXT X ,|EXT X -EXT I |>EXT I When EXT0 is equal to δ, the second calibration value EXT0 is adjusted, and the above step of obtaining the second extinction coefficient profile is returned to based on the adjusted second calibration value EXT0 until EXT0 is equal to δ. X -EXT I |<EXT I ·δ, output the second calibration variable value EXT X , where δ is the relative error; The obtaining of the aerosol extinction coefficient corresponding to the laser radar echo signal in the horizontal direction comprises: obtaining the aerosol extinction coefficient of the laser radar echo signal in the horizontal direction by using a slope method; The slope method is used to obtain the aerosol extinction coefficient of the lidar echo signal in the horizontal direction as the first calibration value EXT I ,include: Assuming that the atmosphere is horizontally uniform, the atmospheric backscatter echo signal power P(Y) received by the lidar at a horizontal distance Y is: P(Y)=P t kY -2 β H exp(-2α H (2) Where P t is the laser emission power (W), k is the radar system constant (W·km 3 ·Sr), β H is the horizontal atmospheric backscatter coefficient (km -1 Sr -1 ), α H Indicates the horizontal atmospheric extinction coefficient (km -1 ); Multiply both sides of formula (2) by the square of the distance, take the logarithm and take the derivative to obtain: Under the condition of uniform atmospheric level, dβ H / dY=0; then: For ln[P(Y)Y 2 ] and Y are fitted by the least square method, and half of its slope is the horizontal atmospheric extinction coefficient α H , α H As the first calibration value EXT I .

2. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 1, characterized in that: The obtaining of the second extinction coefficient profile based on the second calibration value EXT0 includes obtaining the second extinction coefficient profile using a Fernald backward integration method based on the second calibration value EXT0.

3. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 1, characterized in that: The value range of the horizontal distance Y received by the laser radar is 0.06-1km.

4. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 1, wherein: The first height X is greater than the blind spot height. Specifically, the first height X is in the range of 0.06-1 km.

5. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 1, characterized in that: The adjusting the second calibration value EXT0 includes: The ratio of the laser radar echo signal to the molecular signal R(Z C ) Increase the iteration step value to update the ratio of the laser radar echo signal to the molecular signal R(Z C ) target value, based on the ratio of the laser radar echo signal to the molecular signal R(Z C ) The target value obtains the corresponding backscattering coefficient β α (Z C ), using the aerosol extinction backscattering ratio formula S a Get the aerosol extinction coefficient boundary value α a (Z c ), the aerosol extinction coefficient boundary value α a (Z c ) is the atmospheric extinction coefficient corresponding to the calibration point height at the cloud base, which serves as the second calibration value EXT0 corresponding to the target value.

6. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 5, characterized in that: The iteration step value ranges from 0.01 to 0.

5.

7. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 5, characterized in that: The ratio of the laser radar echo signal to the molecular signal R(Z C ) has an initial value of 1.

01.

8. The method for detecting and inverting the subcloud aerosol extinction coefficient using a lidar according to claim 1, characterized in that: The relative error δ ranges from 0.01 to 0.05.

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