All-day laser radar ratio inversion method and device of Raman-meter signal

Abstract

The invention provides a Raman-meter signal all-day laser radar ratio inversion method and device, and the method comprises the steps: carrying out the denoising of signal data of a Raman laser radar in a preset time period, and carrying out the inversion, and obtaining a first aerosol backscattering coefficient profile; applying a plurality of preset laser radar ratios to the inversion of the meter laser radar signal at the same moment to obtain a plurality of second aerosol backscattering coefficient profiles; taking the first aerosol backscattering coefficient profiles at the same moment as a reference standard, calculating a relative error average value of each second aerosol backscattering coefficient profile, and obtaining an optimal laser radar ratio corresponding to the minimum relative error average value; fitting the optimal laser radar ratio with the mean value of the aerosol depolarization ratio of the meter laser radar below the boundary layer height at the corresponding moment to obtain a relation curve; and substituting the mean value of the aerosol depolarization ratio at the current moment into the relation curve to obtain the laser radar ratio. According to the invention, the inversion precision of the aerosol laser radar ratio is improved.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a method and device for all-day laser radar ratio inversion of Raman-Mie signals. Background Art

[0002] LiDAR is an important tool for detecting the vertical profile of atmospheric aerosols, providing high-resolution vertical distribution information of aerosols in the troposphere. To strengthen vertical aerosol detection capabilities at high altitudes and enhance atmospheric environmental monitoring and forecasting and early warning capabilities, Raman-Mie LiDAR and other equipment have been deployed in many locations to build a high-altitude aerosol profile detection network, providing data support for air pollution prevention and control, visibility forecasting, and haze monitoring.

[0003] Mie lidars are typically equipped with a polarization measurement channel and operate both day and night. They can continuously acquire atmospheric aerosol backscatter signals and effectively identify non-spherical particles. They are currently the primary source of lidar inversion products. Mainstream Mie lidar inversion methods (such as the Fernald method) require the lidar ratio to be preset as a constant. In different scenarios such as urban areas and dust storms, empirical values (such as 30-50) are often used as lidar ratios. However, due to the complex types of atmospheric aerosols and their large spatial and temporal variations, setting a fixed value can result in extinction coefficient inversion errors of up to 50%.

[0004] Currently, the main methods for estimating the Mie signal's lidar ratio include joint inversion, type matching, and model calculation. The joint inversion method relies on inverting optical depth using a sun photometer, but is subject to inconsistencies due to factors such as lidar blind spots and signal attenuation. The type matching method requires precise identification of aerosol types, but has poor reliability under mixed aerosol conditions. The model calculation method relies on long-term local data accumulation and is not suitable for newly built sites.

[0005] Due to its unique inelastic backscattering properties, Raman lidar offers the advantage of independently inverting aerosol extinction and backscattering coefficients without requiring a pre-set lidar ratio. However, because the Raman signal itself is extremely weak, it only has a good signal-to-noise ratio at night when background noise is low, making it suitable for high-precision inversion. During the day, significant interference from solar background radiation causes the signal-to-noise ratio to drop significantly, leading to increased inversion errors and, in turn, affecting the accuracy of aerosol optical parameters. This severely limits the practicality and promotional value of Raman lidar in daytime commercial applications. Summary of the Invention

[0006] The present invention provides a method and device for all-day laser radar ratio inversion of Raman-Mie signals, which are used to solve the defect of low laser radar ratio inversion accuracy in the prior art and improve the inversion accuracy of the laser radar ratio.

[0007] The present invention provides a method and device for all-day laser radar ratio inversion of Raman-Mi signal, comprising:

[0008] The signal data collected by the Raman lidar at each moment within a preset time period is de-noised and then inverted to obtain the first aerosol backscattering coefficient profile at each moment;

[0009] Applying a plurality of preset lidar ratios to inversion of signal data collected by the meter lidar at the same moment within the preset time period to obtain a plurality of second aerosol backscatter coefficient profiles at each moment;

[0010] Taking the first aerosol backscatter coefficient profile at the same time as a reference standard, calculating the relative error average of each second aerosol backscatter coefficient profile, and taking the preset lidar ratio corresponding to the minimum relative error average as the optimal lidar ratio;

[0011] Fitting the optimal lidar ratio to the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the meter lidar at the corresponding time to obtain a relationship curve;

[0012] The average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment is substituted into the relationship curve to obtain the lidar ratio at the current moment.

[0013] According to the present invention, a method and device for inverting the all-day Raman-Mie signal ratio is provided. The method removes noise from the signal data collected by the Raman lidar at each moment within a preset time period and then inverts it to obtain the first aerosol backscattering coefficient profile at each moment. The method includes:

[0014] Inverting the signal data collected by the Raman lidar to obtain an aerosol extinction coefficient;

[0015] The first aerosol backscattering coefficient profile is obtained by inverting the signal data collected by the Raman lidar and the Mie lidar, and the aerosol extinction coefficient.

[0016] According to a method and device for inverting the all-day Raman-Mie signal ratio, the following formula is used to de-noise the signal data collected by the Raman lidar at each moment within a preset time period and then invert it to obtain the first aerosol backscattering coefficient profile at each moment:

[0017]

[0018]

[0019] in, is the aerosol backscattering coefficient at wavelength λ0 at height z in the first aerosol backscattering coefficient profile, is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is and The wavelength at z is λ R and the received power of λ0, N R (z) is the number density of nitrogen molecules, and The wavelengths of the laser radar at height z are λ0 and λ R The extinction coefficient of atmospheric molecules, and The wavelengths of the laser radar at height z are λ0 and λ R The aerosol extinction coefficient, P nR and P nM are the background noises received by Raman lidar and Mi lidar respectively, k is a preset coefficient.

[0020] According to a method and apparatus for inverting the all-day lidar ratio of a Raman-Mi signal provided by the present invention, multiple preset lidar ratios are applied to the inversion of signal data collected by the Mi lidar at the same time within the preset time period using the following formula to obtain multiple second aerosol backscatter coefficient profiles at each time:

[0021]

[0022]

[0023] in, is the aerosol backscattering coefficient with wavelength λ0 at height z in the second aerosol backscattering coefficient profile, is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is is the received power at wavelength λ0 at z, P nM They are respectively the background noise received by the lidar at a reference height; the distance correction signal X(z) of the lidar at a reference height and the atmospheric molecular backscattering coefficient The ratio between X(z) / Take the minimum value to determine the reference height z c location; is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; S A is the preset lidar ratio, and The laser radar wavelengths are λ0 and λ R The extinction coefficient of atmospheric molecules, and The wavelengths at height z are λ0 and λ R The aerosol extinction coefficient.

[0024] According to the all-day laser radar ratio inversion method and device of the Raman-Mi signal provided by the present invention, the reference height z c Aerosol backscattering ratio R(z c ) is:

[0025]

[0026] According to a method and device for all-day laser radar ratio inversion of a Raman-Mi signal provided by the present invention, the atmospheric boundary layer height is determined using a gradient method based on the laser radar range correction signal X(z), and the formula is:

[0027]

[0028] Wherein, the atmospheric boundary layer height z PBLH is the height z at which the gradient of the lidar range correction signal X(z) at height z is minimum.

[0029] According to a method and device for all-day laser radar ratio inversion of a Raman-Mie signal provided by the present invention, the atmospheric boundary layer height is determined using a wavelet covariance transformation function based on the laser radar range correction signal X(z), and the formula is:

[0030] z PBLH =arg min(W f (a,b));

[0031]

[0032] Among them, z PBLH is the atmospheric boundary layer height, h is the wavelet function, W f (a, b) is the wavelet covariance transformation function, a refers to the spectral width of the wavelet function, which is also the spatial range or calculation step size, b refers to the height position of the center value of the wavelet function, X(z) is the laser radar distance correction signal that changes with height z, z t and zb They refer to the top height and bottom height of the laser radar backscatter echo signal, respectively. -1 is the inverse of the computational step size.

[0033] According to a method and device for inverting the all-day lidar ratio of a Raman-Mi signal provided by the present invention, taking into account that atmospheric aerosols mainly accumulate below the atmospheric boundary layer, the optimal lidar ratio is fitted with the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the Mi lidar at the corresponding time to obtain a relationship curve, including:

[0034] Determine the optimal lidar ratio and fit it with the average of the aerosol depolarization ratio below the atmospheric boundary layer height collected by the meter lidar at the corresponding time and the average of the logarithm of the lidar distance correction signal to obtain a relationship curve;

[0035] The present invention also provides a laser radar ratio inversion device for a meter laser radar signal, comprising:

[0036] A first inversion module is used to de-noise and invert the signal data collected by the Raman lidar at each moment within a preset time period to obtain a first aerosol backscattering coefficient profile at each moment;

[0037] A second inversion module is configured to apply a plurality of preset lidar ratios to the inversion of signal data collected by the meter lidar at the same moment within the preset time period, to obtain a plurality of second aerosol backscattering coefficient profiles at each moment;

[0038] A selection module is configured to calculate a relative error average of each second aerosol backscatter coefficient profile using the first aerosol backscatter coefficient profile at the same time as a reference standard, and use the preset lidar ratio corresponding to the minimum relative error average as the optimal lidar ratio;

[0039] A fitting module, configured to fit the optimal lidar ratio to an average of aerosol depolarization ratios below the atmospheric boundary layer height collected by the meter lidar at a corresponding time to obtain a relationship curve;

[0040] An acquisition module is used to substitute the average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment into the relationship curve to obtain the lidar ratio at the current moment.

[0041] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, it implements the all-day lidar ratio inversion method and device for the Raman-Mi signal as described in any one of the above.

[0042] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method and device for all-day laser radar ratio inversion of the Raman-Mi signal as described in any one of the above are implemented.

[0043] The present invention also provides a computer program product, comprising a computer program, which, when executed by a processor, implements the all-day lidar ratio inversion method and device for Raman-Mi signal as described in any one of the above.

[0044] The present invention provides a method and device for inverting the all-day Raman-Mie signal lidar ratio, which denoises the signal data collected by the Raman lidar at each moment in a preset time period and then inverts it, thereby obtaining a high-quality aerosol inversion result based on the Raman signal as a reference benchmark; optimizes the lidar ratio of the Mie data by the minimum mean relative error (MRE), introduces the optimal lidar ratio of the preset time period, and fits the mean of the aerosol depolarization ratio below the boundary layer collected by the Mie lidar, thereby realizing the inversion of the high-precision lidar ratio of the Mie data for all-day periods; adaptively constructs the lidar ratio based on the observation data, thereby avoiding the systematic deviation caused by the fixed ratio, is suitable for automated deployment, and can be used for continuous aerosol monitoring or batch processing of large data. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 1. It is a flow chart of the all-day laser radar ratio inversion method and device of the Raman-Mi signal provided by the present invention;

[0047] Figure 2 1. It is a schematic diagram of a process for obtaining the optimal lidar ratio in the all-day lidar ratio inversion method and device for Raman-Mi signal provided by the present invention;

[0048] Figure 3 Schematic diagram of aerosol backscattering coefficient and boundary layer height inverted by Raman lidar and Mie lidar at different times in the all-day lidar ratio inversion method and device for Raman-Mie signals provided by the present invention;

[0049] Figure 4 Schematic diagram of the deviation of aerosol backscattering coefficients inverted from Raman and Mie data due to differences in LiDAR ratios at different times in the all-day LiDAR ratio inversion method and device for Raman-Mie signals provided by the present invention;

[0050] Figure 5 Schematic diagram of aerosol extinction coefficient based on Mie lidar data at different times in the all-day lidar ratio inversion method and device for Raman-Mie signals provided by the present invention;

[0051] Figure 6 Schematic diagram of the structure of the all-day laser radar ratio inversion device for Raman-Mi signal provided by the present invention;

[0052] Figure 7 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0054] The following combination Figure 1 The present invention describes a method and device for all-day laser radar ratio inversion of Raman-Mi signal, comprising:

[0055] Step 101: Denoise and invert the signal data collected by the Raman lidar at each moment within a preset time period to obtain a first aerosol backscattering coefficient profile at each moment;

[0056] Raman lidar uses a laser to emit a single wavelength laser beam into the atmosphere. When this laser beam interacts with atmospheric molecules or aerosol particles, in addition to elastic scattering (i.e., Rayleigh and Mie scattering), it also produces some inelastic scattering, namely Raman scattering. Its wavelength undergoes a predictable shift, which is called the Raman wavelength.

[0057] Considering that the signal-to-noise ratio of the Raman channel data is higher at night and in the early morning and the background noise is lower, it is easier to extract the real and effective signal through various signal denoising methods.

[0058] Signal data denoising can be performed by extracting effective information through signal processing techniques such as wavelet transforms, ensuring the reliability of the reference results. Priority is given to inverting the nighttime and early morning Raman signal data after wavelet smoothing to obtain a high-precision first aerosol backscattering coefficient profile, which is used as the reference standard.

[0059] Step 102, applying a plurality of preset lidar ratios to inversion of signal data collected by the meter lidar at the same moment within the preset time period, to obtain a plurality of second aerosol backscatter coefficient profiles at each moment;

[0060] Mie lidar emits a laser beam of a specific wavelength into the atmosphere. When the laser encounters particles larger than molecular size, such as aerosol particles or water droplets, Mie scattering (particle scattering) occurs. A portion of the elastically scattered light with the same wavelength as the emission will return along the original path and be detected by the lidar receiver.

[0061] The lidar ratio is the ratio of the aerosol extinction coefficient to the aerosol backscatter coefficient. Set the lidar ratio search space and step size. For example, set the search space to 1 to 120 with a step size of 1. Select multiple preset lidar ratios from these ratios to form a lidar ratio sequence. Apply these preset lidar ratios to the Mie data inversion at the same time to obtain multiple second aerosol backscatter coefficient profiles at each time.

[0062] Step 103: Using the first aerosol backscatter coefficient profile at the same time as a reference standard, calculate the relative error average of each second aerosol backscatter coefficient profile, and use the preset lidar ratio corresponding to the minimum relative error average (MRE) as the optimal lidar ratio;

[0063] Using the Raman data inversion results as a reference standard, each second aerosol backscattering coefficient profile inverted from the Mie signal data at each moment is compared with the first aerosol backscattering coefficient profile inverted from the Raman signal data, and the mean relative error (MRE) of each second aerosol backscattering coefficient profile is calculated. The definition of MRE is as follows:

[0064]

[0065] in, and They are located at the i-th height z i The aerosol backscattering coefficient is obtained by inverting the Mie signal data and the Raman signal data, where n is the number of altitudes.

[0066] The flow chart for obtaining the optimal lidar ratio is as follows: Figure 2 As shown in the figure, the lidar ratio corresponding to the minimum MRE is considered to be the optimal value at that moment, and the aerosol optical parameters inverted from the Mie data based on the optimal lidar ratio are considered to be relatively accurate.

[0067] Step 104, fitting the optimal lidar ratio to the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the lidar at the corresponding time to obtain a relationship curve;

[0068] The optimal lidar ratios at multiple times during the night and early morning were calculated and used to establish an empirical model based on the average of the aerosol depolarization ratios below the atmospheric boundary layer altitude collected by the corresponding Mie lidar at the corresponding time. The optimal lidar ratios at multiple times during the night and early morning were calculated and incorporated into the optimal time period for daytime inversion. For example, data from 00:00 to 60:00 and 18:00 to midnight were extrapolated to 60:00 to 18:00. This enabled dynamic assignment of lidar ratio parameters for all-day Mie data inversion. This addressed the issue of poor signal-to-noise in the daytime Raman channel, which prevented direct reference.

[0069] Polarization meter lidar can detect the perpendicular component and parallel component (relative to the polarization plane of the outgoing light) of the backscattered echoes from atmospheric molecules and aerosol particles. The ratio of these two components is called the linear depolarization ratio. Taking into account the difference in optical and electronic gain of the two channels, the linear depolarization ratio is defined as follows:

[0070]

[0071] Among them, P ⊥ and P || are the vertical component and parallel component detected by the lidar, respectively, and K is the calibration constant, which describes the difference between the optical parameters of the two channels.

[0072] Step 105: Substitute the average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment into the relationship curve to obtain the lidar ratio at the current moment.

[0073] According to the fitted relationship curve, the lidar ratio of the Mie data was calculated from the average aerosol depolarization ratio below the boundary layer from 6:00 to 18:00 on the same day, thereby providing the lidar ratio for the Mie data throughout the day and realizing the unified inversion of day and night aerosol information.

[0074] This embodiment obtains high-quality Raman inversion results as a reference benchmark by denoising the signal data collected by the Raman lidar at each moment in a preset time period and then inverting it. The lidar ratio of the Mie data is optimized by minimum mean relative error (MRE). The optimal lidar ratio in the preset time period is introduced and fitted with the mean of the aerosol depolarization ratio below the boundary layer collected by the Mie lidar to achieve high-precision inversion of the lidar ratio of Mie data throughout the day. The lidar ratio is adaptively constructed based on the observation data, avoiding the systematic deviation caused by a fixed ratio. The method is suitable for automated deployment and can be used for continuous aerosol monitoring or batch processing of big data.

[0075] Based on the above embodiment, in this embodiment, the signal data collected by the Raman lidar at each moment within a preset time period is de-noised and then inverted to obtain the first aerosol backscattering coefficient profile at each moment, including:

[0076] Inverting the signal data collected by the Raman lidar to obtain an aerosol extinction coefficient;

[0077] The first aerosol backscattering coefficient profile is obtained by inverting the signal data collected by the Raman lidar and the Mie lidar, and the aerosol extinction coefficient.

[0078] Based on the above embodiment, in this embodiment, the signal data collected by the Raman lidar at each moment within a preset time period is de-noised and inverted using the following formula to obtain the first aerosol backscattering coefficient profile at each moment:

[0079]

[0080] in, is the aerosol backscattering coefficient at wavelength λ0 at height z in the first aerosol backscattering coefficient profile, is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is and They are the wavelength λ at height z R and the received power of λ0, N R (z) is the number density of nitrogen molecules, and The wavelengths of the laser radar at height z are λ0 and λ R The atmospheric molecular extinction coefficients are the extinction caused by atmospheric molecular absorption and Rayleigh scattering; and The wavelengths at height z are λ0 and λ R Aerosol extinction coefficient; P nR and P nMThey are the background noise received by Raman and Mie lidars respectively. The background noise mainly includes the background light noise in the atmosphere and the thermoelectric noise generated by the lidar detection system itself. Among them, the background light noise is usually estimated by extracting the average value of the high-altitude area in the lidar echo signal. Because in this altitude range, the aerosol concentration is extremely low, the echo signal basically does not contain aerosol information, and the change is stable, which is suitable as a background light reference. The thermoelectric noise generated by the Raman lidar system is generally removed by methods such as wavelet transform; in contrast, the Mie lidar has a smaller thermoelectric noise effect due to its high signal-to-noise ratio and can usually be ignored. Generally, the particle size spectrum of aerosol particles follows the Junge distribution, so the aerosol extinction coefficient is related to the wavelength λ k Inversely proportional, so k is a preset coefficient. Usually, the size of the aerosol is comparable to the laser wavelength, satisfying k = 1.

[0081] Based on the above embodiment, in this embodiment, multiple preset lidar ratios are applied to the inversion of signal data collected by the meter lidar at the same time within the preset time period through the following formula to obtain multiple second aerosol backscatter coefficient profiles at each time:

[0082]

[0083]

[0084]

[0085] in, is the aerosol backscattering coefficient with wavelength λ0 at height z in the second aerosol backscattering coefficient profile, is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is is the received power at wavelength λ0 at z, P nM are the background noise received by the lidar in meters; usually the high altitude position is selected as the reference height, and the reference height z c There is very little or even no aerosol at the reference altitude, so the distance correction signal X(z) of the lidar at the reference altitude is proportional to the atmospheric molecular backscatter coefficient. The ratio between The minimum value should be taken so that the reference height z can be determined c location; is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; S Ais the preset lidar ratio, and The laser radar wavelengths are λ0 and λ R The extinction coefficient of atmospheric molecules, and The wavelengths at height z are λ0 and λ R The aerosol extinction coefficient.

[0086] Based on the above embodiment, the aerosol backscattering ratio at height z in this embodiment is defined as follows:

[0087]

[0088] Generally, there is less aerosol at the reference height, and the aerosol backscatter ratio at this height can be preset to 1.01. c Aerosol backscattering ratio R(z c ) is:

[0089]

[0090] Based on the above embodiment, the atmospheric boundary layer height in this embodiment is determined using the gradient method based on the laser radar distance correction signal X(z), and the formula is:

[0091]

[0092] Wherein, the atmospheric boundary layer height z PBLH is the height z at which the gradient of the lidar range correction signal X(z) at height z is minimum.

[0093] Based on the above embodiment, the atmospheric boundary layer height in this embodiment is determined based on the laser radar distance correction signal X(z) using the wavelet covariance transformation function, and the formula is:

[0094] z PBLH =arg min(W f (a,b));

[0095]

[0096]

[0097] Among them, z PBLH is the atmospheric boundary layer height, h is the Haar wavelet function, W f (a, b) is the wavelet covariance transformation function, a refers to the spectral width of the wavelet function, which is also the spatial range or calculation step size, b refers to the height position of the center value of the wavelet function, X(z) is the laser radar distance correction signal that changes with height z, z t and z bThey refer to the top height and bottom height of the laser radar backscatter echo signal, respectively. -1 is the inverse of the computational step size.

[0098] In the selected range of the laser radar backscatter echo signal height, assuming that the step size a is selected as a certain value, the wavelet covariance transformation function value that changes with the height b is calculated. PBLH ) is generally the position where the gradient value of the laser radar distance correction signal changes the most. The boundary layer height can be calculated by the wavelet covariance transform method. The position where the minimum value of the appropriate wavelet covariance transform function is located can be selected as z PBLH .

[0099] On the basis of the above embodiment, in this embodiment, considering that atmospheric aerosols mainly accumulate below the atmospheric boundary layer, the optimal lidar ratio is fitted with the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the lidar at the corresponding time to obtain a relationship curve, including:

[0100] The optimal lidar ratio is determined and fitted with the average value of the aerosol depolarization ratio below the atmospheric boundary layer height collected by the meter lidar at the corresponding time and the average value of the logarithm of the lidar distance correction signal to obtain a relationship curve.

[0101] For example, the optimal lidar ratios at multiple times during the night (6:00 PM - midnight) and the morning (12:00 AM - 6:00 AM) were calculated and compared with the mean depolarization ratios of the aerosols below the boundary layer in the Mie data at those times to establish an empirical model, resulting in a well-fitted relationship curve. Based on this relationship curve, the lidar ratios of the Mie data were inferred from the mean depolarization ratios of the aerosols below the boundary layer between 6:00 AM and 6:00 PM that day. This provided the lidar ratios for the Mie data throughout the day, enabling a unified inversion of aerosol information for both day and night.

[0102] We can also calculate the optimal lidar ratio at multiple times between 18:00 and 24:00 at night and between 0:00 and 6:00 in the morning, and establish an empirical model with the mean of the aerosol depolarization ratio below the boundary layer of the Mie data at the corresponding time and the mean of the logarithm of the lidar distance correction signal. The empirical model is Using linear regression, polynomial regression, and machine learning regression methods, the lidar ratio is fitted to an empirical formula based on the mean of the aerosol depolarization ratio below the boundary layer and the logarithm of the lidar range-corrected signal from the Mie data at the corresponding time. Based on this empirical relationship, the lidar ratio of the Mie data is then inferred from the mean of the aerosol depolarization ratio below the boundary layer and the logarithm of the lidar range-corrected signal from the Mie data between 6:00 and 18:00 that day. This provides the lidar ratio for all-day Mie data, enabling a unified inversion of aerosol information for both day and night.

[0103] Figure 3Figures (a) to (h) are the aerosol backscattering coefficient and boundary layer height inverted by Raman and Mie lidar at different times.

[0104] Figure 4 Figures (a) to (h) show the deviations of aerosol backscattering coefficients inverted from Raman and Mie data due to differences in lidar ratios at different times.

[0105] Figure 5 Figures (a) to (h) are the aerosol extinction coefficients based on Mie lidar data at different times.

[0106] The following describes the all-day laser radar ratio inversion device for the Raman-Mié signal provided by the present invention. The all-day laser radar ratio inversion device for the Raman-Mié signal described below and the all-day laser radar ratio inversion method and device for the Raman-Mié signal described above can be referenced to each other.

[0107] like Figure 6 As shown, the apparatus includes a first inversion module 601, a second inversion module 602, a selection module 603, a fitting module 604 and an acquisition module 605, wherein:

[0108] The first inversion module 601 is used to de-noise the signal data collected by the Raman lidar at each moment within a preset time period and then invert it to obtain the first aerosol backscattering coefficient profile at each moment;

[0109] The second inversion module 602 is configured to apply a plurality of preset lidar ratios to the inversion of signal data collected by the meter lidar at the same moment within the preset time period, to obtain a plurality of second aerosol backscatter coefficient profiles at each moment;

[0110] The selection module 603 is configured to calculate the relative error average of each second aerosol backscatter coefficient profile using the first aerosol backscatter coefficient profile at the same time as a reference standard, and use the preset lidar ratio corresponding to the minimum relative error average as the optimal lidar ratio;

[0111] The fitting module 604 is used to fit the optimal lidar ratio with the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the lidar at the corresponding time to obtain a relationship curve;

[0112] The acquisition module 605 is used to substitute the average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment into the relationship curve to obtain the lidar ratio at the current moment.

[0113] This embodiment denoises the signal data collected by the Raman lidar at each moment within a preset time period and then inverts it to obtain high-quality Raman inversion results as a reference benchmark; the lidar ratio of the Mie data is optimized by minimum mean relative error (MRE), and the optimal lidar ratio of the preset time period is introduced to fit the mean of the aerosol depolarization ratio below the boundary layer collected by the Mie lidar to achieve inversion of the high-precision lidar ratio of the Mie data throughout the day; the lidar ratio is adaptively constructed based on the observation data, avoiding the systematic deviation caused by fixed ratios, making it suitable for automated deployment and can be used for continuous aerosol monitoring or batch processing of big data.

[0114] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as Figure 7 As shown, the electronic device may include: a processor (processor) 710, a communication interface (Communications Interface) 720, a memory (memory) 730 and a communication bus 740, wherein the processor 710, the communication interface 720, and the memory 730 communicate with each other through the communication bus 740. The processor 710 can call the logic instructions in the memory 730 to execute the all-day lidar ratio inversion method and device for the Raman-Mi signal, which includes: denoising the signal data of the Raman lidar within a preset time period and inverting it to obtain a first aerosol backscattering coefficient profile; applying multiple preset lidar ratios to the inversion of the Mi lidar at the same time to obtain multiple second aerosol backscattering coefficient profiles; using the first aerosol backscattering coefficient profile at the same time as a reference standard, calculating the relative error average of each second aerosol backscattering coefficient profile to obtain the optimal lidar ratio corresponding to the minimum relative error average; fitting the optimal lidar ratio with the average aerosol depolarization ratio of the Mi lidar below the boundary layer height at the corresponding time to obtain a relationship curve; substituting the average aerosol depolarization ratio at the current time into the relationship curve to obtain the lidar ratio.

[0115] In addition, the logic instructions in the above-mentioned memory 730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0116] On the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the all-day lidar ratio inversion method and device for the Raman-Mi signal provided by the above-mentioned methods. The method includes: denoising the signal data of the Raman lidar within a preset time period and then inverting it to obtain a first aerosol backscattering coefficient profile; applying multiple preset lidar ratios to the inversion of the Mi lidar at the same time to obtain multiple second aerosol backscattering coefficient profiles; using the first aerosol backscattering coefficient profile at the same time as a reference standard, calculating the relative error average of each second aerosol backscattering coefficient profile to obtain the optimal lidar ratio corresponding to the minimum relative error average; fitting the optimal lidar ratio with the average aerosol depolarization ratio of the Mi lidar below the boundary layer height at the corresponding time to obtain a relationship curve; substituting the average aerosol depolarization ratio at the current time into the relationship curve to obtain the lidar ratio.

[0117] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the all-day lidar ratio inversion method and device for the Raman-Mi signal provided by the above-mentioned methods, the method comprising: denoising the signal data of the Raman lidar within a preset time period and then inverting it to obtain a first aerosol backscattering coefficient profile; applying multiple preset lidar ratios to the inversion of the Mi lidar at the same time to obtain multiple second aerosol backscattering coefficient profiles; using the first aerosol backscattering coefficient profile at the same time as a reference standard, calculating the relative error average of each second aerosol backscattering coefficient profile to obtain the optimal lidar ratio corresponding to the minimum relative error average; fitting the optimal lidar ratio with the average aerosol depolarization ratio of the Mi lidar below the boundary layer height at the corresponding time to obtain a relationship curve; substituting the average aerosol depolarization ratio at the current time into the relationship curve to obtain the lidar ratio.

[0118] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0119] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method and device for all-day laser radar ratio inversion of Raman-Mi signal, characterized in that: include: The signal data collected by the Raman lidar at each moment within a preset time period is de-noised and then inverted to obtain the first aerosol backscattering coefficient profile at each moment; Applying a plurality of preset lidar ratios to inversion of signal data collected by the meter lidar at the same moment within the preset time period to obtain a plurality of second aerosol backscatter coefficient profiles at each moment; Taking the first aerosol backscatter coefficient profile at the same time as a reference standard, calculating the relative error average of each second aerosol backscatter coefficient profile, and taking the preset lidar ratio corresponding to the minimum relative error average as the optimal lidar ratio; Fitting the optimal lidar ratio to the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the meter lidar at the corresponding time to obtain a relationship curve; The average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment is substituted into the relationship curve to obtain the lidar ratio at the current moment.

2. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 1, characterized in that: After denoising, the signal data collected by the Raman lidar at each moment within a preset time period is inverted to obtain the first aerosol backscattering coefficient profile at each moment, including: Inverting the signal data collected by the Raman lidar to obtain an aerosol extinction coefficient; The first aerosol backscattering coefficient profile is obtained by inverting the signal data collected by the Raman lidar and the Mie lidar, and the aerosol extinction coefficient.

3. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 2, characterized in that: The signal data collected by the Raman lidar at each moment within the preset time period is de-noised and inverted using the following formula to obtain the first aerosol backscattering coefficient profile at each moment: in, is the aerosol backscattering coefficient at wavelength λ0 at height z in the first aerosol backscattering coefficient profile, is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is and The wavelength at z is λ R and the received power of λ0, N R (z) is the number density of nitrogen molecules, and The wavelengths of the laser radar at height z are λ0 and λ R The extinction coefficient of atmospheric molecules, and The wavelengths of the laser radar at height z are λ0 and λ R The aerosol extinction coefficient, P nR and P nM are the background noises received by Raman lidar and Mi lidar respectively, k is a preset coefficient.

4. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 1, characterized in that: Applying multiple preset lidar ratios to the inversion of signal data collected by the meter lidar at the same time within the preset time period is performed using the following formula to obtain multiple second aerosol backscattering coefficient profiles at each time: in, is the aerosol backscattering coefficient with wavelength λ0 at height z in the second aerosol backscattering coefficient profile, is the backscattering coefficient of atmospheric molecules with wavelength λ0 at height z, is the reference height z c The backscattering coefficient of atmospheric molecules at wavelength λ0 is is the received power at wavelength λ0 at z, P nM They are respectively the background noise received by the lidar at a reference height; the distance correction signal X(z) of the lidar at a reference height and the atmospheric molecular backscattering coefficient The ratio between Take the minimum value to determine the reference height z c location; is the reference height z c The aerosol backscattering coefficient at wavelength λ0 is determined according to the pre-set aerosol backscattering ratio; S A is the preset lidar ratio, and The laser radar wavelengths are λ0 and λ R The extinction coefficient of atmospheric molecules, and The wavelengths at height z are λ0 and λ R The aerosol extinction coefficient.

5. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 3 or 4, characterized in that: Reference height z c Aerosol backscattering ratio R(z c ) is:

6. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 1, characterized in that: The atmospheric boundary layer height is determined using the gradient method based on the laser radar distance correction signal X(z), and the formula is: Wherein, the atmospheric boundary layer height z PBLH is the height z at which the gradient of the lidar range correction signal X(z) at height z is minimum.

7. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 1, characterized in that: The atmospheric boundary layer height is determined based on the laser radar range correction signal X(z) using the wavelet covariance transformation function, and the formula is: With PBLH =arg min(W f (a,b)); Among them, z PBLH is the atmospheric boundary layer height, h is the wavelet function, W f (a, b) is the wavelet covariance transformation function, a refers to the spectral width of the wavelet function, which is also the spatial range or calculation step size, b refers to the height position of the center value of the wavelet function, X(z) is the laser radar distance correction signal that changes with height z, z t and z b They refer to the top height and bottom height of the laser radar backscatter echo signal, respectively. -1 is the inverse of the computational step size.

8. The all-day laser radar ratio inversion method and device of Raman-Mi signal according to claim 1, characterized in that: Considering that atmospheric aerosols mainly accumulate below the atmospheric boundary layer, the optimal lidar ratio is fitted with the average of the aerosol depolarization ratios below the atmospheric boundary layer height collected by the lidar at the corresponding time to obtain a relationship curve, including: The optimal lidar ratio is determined and fitted with the average value of the aerosol depolarization ratio below the atmospheric boundary layer height collected by the meter lidar at the corresponding time and the average value of the logarithm of the lidar distance correction signal to obtain a relationship curve.

9. A full-time laser radar ratio inversion device for Raman-Mi signal, characterized in that: include: A first inversion module is used to de-noise and invert the signal data collected by the Raman lidar at each moment within a preset time period to obtain a first aerosol backscattering coefficient profile at each moment; A second inversion module is configured to apply a plurality of preset lidar ratios to the inversion of signal data collected by the meter lidar at the same moment within the preset time period, to obtain a plurality of second aerosol backscattering coefficient profiles at each moment; A selection module is configured to calculate a relative error average of each second aerosol backscatter coefficient profile using the first aerosol backscatter coefficient profile at the same time as a reference standard, and use the preset lidar ratio corresponding to the minimum relative error average as the optimal lidar ratio; A fitting module, configured to fit the optimal lidar ratio to an average of aerosol depolarization ratios below the atmospheric boundary layer height collected by the meter lidar at a corresponding time to obtain a relationship curve; An acquisition module is used to substitute the average value of the aerosol depolarization ratio below the boundary layer collected by the meter lidar at the current moment into the relationship curve to obtain the lidar ratio at the current moment.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the all-day lidar ratio inversion method and device of the Raman-Mi signal as described in any one of claims 1 to 8 are implemented.

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