CN113358160B - Atmospheric data measuring method and system - Google Patents
Atmospheric data measuring method and system Download PDFInfo
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- CN113358160B CN113358160B CN202110774905.4A CN202110774905A CN113358160B CN 113358160 B CN113358160 B CN 113358160B CN 202110774905 A CN202110774905 A CN 202110774905A CN 113358160 B CN113358160 B CN 113358160B
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Abstract
The application discloses an atmospheric data measuring method and system, which are used for solving the problem that the reliability, accuracy and timeliness of the existing atmospheric data measuring system cannot meet the requirements of a new generation of aircraft. The system comprises a laser light source, a detection unit and a computer: the laser light source comprises a signal generator for generating a waveform of tuning laser, a laser controller for controlling the temperature and the injection current of the tunable laser, and the tunable laser for emitting the tuning laser with corresponding wavelength; the detection unit comprises an optical lens group for receiving the backward scattered light of the tuned laser after the scattering and absorption of the gas molecules, and a detector for converting the signal of the backward scattered light into a corresponding electric signal; the computer acquires digital signals corresponding to the electrical signals to obtain detection data, an absorption spectral line shape is obtained through base line fitting of the detection data, and linear function fitting is carried out on the absorption spectral line shape to obtain corresponding absorption spectral line parameters for calculating atmospheric data.
Description
Technical Field
The present application relates to the field of atmospheric data measurement, and in particular, to an atmospheric data measurement method and system.
Background
The air data is important input information of an aircraft flight control system and an engine control system, the accurate and reliable air data is an important guarantee for safe and stable flight of the aircraft, and the air data sensing is one of the key technologies of modern aircraft. With the rapid development of aircraft technology, the new generation of aircraft has faster flight speed, stronger maneuverability and larger attack angle, needs to fly in the near space, depends on the accurate measurement of atmospheric data, and simultaneously also puts higher requirements on the atmospheric data sensing technology.
At present, in the process of measuring atmospheric data, the atmospheric data are respectively measured under different time-space conditions through a plurality of sensors with different principles, so that the reliability, the accuracy and the timeliness of the measured atmospheric data have problems, and the requirements of a new generation of aircrafts cannot be met.
Disclosure of Invention
The embodiment of the application provides an atmospheric data measuring method and system, which are used for solving the problem that the reliability, accuracy and timeliness of the conventional atmospheric data measuring system cannot meet the requirements of a new generation of aircraft.
The atmospheric data measurement system provided by the embodiment of the application is characterized by comprising a laser light source, a detection unit and a computer; the laser light source comprises a signal generator, a laser controller and a tunable laser; the signal generator is used for generating a waveform of tuned laser light, the laser controller is used for controlling the temperature and the injection current of the tunable laser, and the tunable laser is used for emitting the tuned laser light with corresponding wavelength; the detection unit comprises an optical filter, an optical lens group and a detector; the optical filter filters stray light in the backward scattering light of the tuned laser after gas molecule scattering and absorption, the optical lens group is used for receiving the filtered backward scattering light, and the detector is an array type, image type or single-point type photoelectric conversion device and is used for converting the backward scattering light into a corresponding electric signal through photoelectric conversion; the computer is used for obtaining digital signals corresponding to the electric signals to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, and performing linear function fitting on the absorption spectral line shapes to obtain corresponding absorption spectral line parameters for calculating atmospheric data.
The atmospheric data measurement method provided by the embodiment of the application comprises the following steps: generating a waveform of the tuned laser by a signal generator; emitting tuning laser with corresponding wavelength by a tunable laser to irradiate the air; an optical lens group is adopted to receive the back scattered light of the tuned laser after the back scattered light and the absorbed light of the gas molecules; converting the backscattered light into a corresponding electrical signal by a detector; and acquiring digital signals corresponding to the electric signals through a computer to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, and performing linear function fitting on the absorption spectral line shapes to obtain corresponding absorption spectral line parameters for calculating atmospheric data.
The embodiment of the application provides an atmospheric data measuring method and system, which at least have the following beneficial effects: by detecting the composite spectrum signals of atmospheric scattering and oxygen molecule absorption, multiple parameters of air such as density, oxygen concentration, air temperature, pressure and speed are inverted at the same time, and the synchronous measurement of multiple parameters of atmospheric data required by an aircraft is realized. The method is not limited by the height and the speed of the aircraft, can obtain reliable backscattering signals at different heights, meets the requirement of large airspace application from the near ground to the near space, adapts to various different flight modes and environments, improves the reliability of atmospheric data measurement, improves the measurement precision, and is beneficial to guaranteeing the flight safety.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic structural diagram of an atmospheric data measurement system according to an embodiment of the present disclosure;
FIG. 2 is a schematic view of a scattering system provided in an embodiment of the present application;
FIG. 3 is a flow chart of an atmospheric data measurement method provided by an embodiment of the present application;
fig. 4 is a detailed flowchart corresponding to fig. 3 according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 is a schematic structural diagram of an atmospheric data measurement system according to an embodiment of the present application.
As shown in fig. 1, the atmospheric data measurement system includes a laser light source 1, a detection unit 2, and a computer 3.
The laser light source 1 comprises a signal generator 11, a laser controller 12 and a tunable laser 13; the signal generator 11 is used for generating a waveform of the tuned laser light, the laser controller 12 is used for controlling the temperature and the injection current of the tunable laser, and the tunable laser 13 is used for emitting the tuned laser light with corresponding wavelength. The detection unit 2 comprises a filter 21, an optical lens group (not shown in fig. 1), a detector 22; the optical filter 21 is configured to filter stray light in the backscattered light after the tuned laser is scattered and absorbed by the gas molecules, the optical lens group is configured to receive the backscattered light after the filtering processing, and the detector 22 is configured to convert the collected backscattered light into a corresponding electrical signal through photoelectric conversion, and send the electrical signal to the computer 3. The detector may be an array, image, or single-point photoelectric converter, such as an enhanced charge coupled device (ICCD) camera, a CCD camera, a CMOS camera, an APD detector, a single photon detector, or any other device capable of covering the used wavelength. The computer 3 is used for obtaining digital signals corresponding to the electric signals to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, performing linear function fitting on the absorption spectral line shapes, obtaining corresponding absorption spectral line parameters according to feedback iteration in a multi-iteration process, and then calculating to obtain corresponding atmospheric data according to the absorption spectral line parameters. Wherein the detection data may be represented as a parameter of the backscattered light (such as light intensity).
In one embodiment, the main gas components in the atmosphere such as oxygen, carbon dioxide, methane and the like have small volume-to-concentration changes within 100km of high altitude, have characteristic absorption effects and are suitable for measuring atmospheric data. Therefore, the present application can set the gas molecules used for measurement and determine the center wavelength of the laser signal corresponding thereto. For example, a laser signal of 760nm or other spectrum capable of interacting with oxygen molecules is used to generate characteristic absorption of oxygen molecules.
In one embodiment, the tunable laser cyclically emits laser light of different wavelengths according to a preset period when emitting the laser light to form periodic emission. The detector 22 collects electrical signals of backscattered light corresponding to the tuned laser beams of different wavelengths, respectively, to form periodic data. The computer 3 selects the detection data belonging to different periods according to the periodicity of the data acquired by the detector as the data to be measured, performs average processing on the data to be measured, and uses the processed data to be measured as the data to be measured in one period, so that random errors can be reduced, and the accuracy of atmospheric data measurement can be improved. The data to be detected should satisfy a preset condition, such as a signal-to-noise ratio higher than a preset value, which is representative, so that the characteristics of the corresponding detection data can be fully expressed.
In one embodiment, when selecting the light spots to be measured, the computer 3 selects multiple groups of light spots to be measured according to different optical path lengths and scattering angles. And then, after the corresponding atmospheric data are respectively obtained by subsequent calculation according to the multiple groups of light spots to be measured, averaging the multiple groups of corresponding atmospheric data to obtain the average value of the multiple groups of atmospheric data, wherein the average value is used as the final atmospheric data, so that the accuracy of atmospheric data measurement is improved, and errors are reduced.
In one embodiment, fig. 2 is a schematic view of a scattering system provided in an embodiment of the present application. In FIG. 2, L is an ultraviolet laser, a detector receives scattered light and converts the scattered light into an electrical signal, r is the distance between the two, and θ is1、θ2Respectively the angle between the laser and the ICCD and the horizontal plane, phi1Is the divergence angle of the laser, phi2For the receiving field angle of the detector, θ s is the scattering angle, and V is the scattering area.
In one embodiment, the measurement system may be arranged from three directions of the X, Y, Z axis of the three-dimensional coordinate system, and measure the atmospheric data respectively, and mutually verify the data measured from the three directions, and determine the accuracy of the measured atmospheric data. Alternatively, the atmospheric data measured by the three methods can be averaged to improve the accuracy of the atmospheric data measurement.
When the computer calculates the detection data, the method is specifically realized by the following modes:
firstly, the backscattered light includes rayleigh scattering of gas molecules and rice scattering of aerosol, and the computer needs to describe the corresponding scattered light by respectively adopting a rice scattering model or a rayleigh scattering model according to scattering information carried in the detection data and a relation between the diameter of the gas molecules and the wavelength of the tuning laser. The scattering effect between the tuning laser and the air particles depends on the size relation between the laser wavelength and the particle diameter, if the particle diameter is close to or larger than the wavelength, the light intensity of the scattering signal is described through a meter scattering model, and if the particle diameter is far smaller than the wavelength, the light intensity of the scattering signal is described through a Rayleigh scattering model.
Secondly, according to absorption information carried in the detection data, a Gaussian function describing a Doppler broadening line shape and a Lorentzian function describing a collision broadening line shape are convoluted to obtain a gas absorption line broadening line shape described by a Forgt function.
In particular, molecular absorption is selective, and occurs only when the incident light wavenumber (or wavelength) resonates with a certain transition of the gas molecule. When the gas molecules are assumed to be oxygen molecules, the absorption depends on the characteristic absorption spectrum of the oxygen molecules. The absorption of gas molecules follows the Lambert beer law, the gas absorption spectrum depends on the molecular structure, the corresponding transition energy level and the environment condition, and the gas absorption spectrum is influenced by the environment condition to present different linear shapes. In low pressure environments or high temperature environments, one of the main factors in broadening of the gas absorption line is doppler broadening, which results from the thermal motion of the gas molecules. The molecular thermal motion rule follows Maxwell-Boltzmann statistical distribution, the higher the temperature is, the more violent the molecular motion is, the Doppler broadening effect is enhanced, and can be described by a Gaussian function. Collisions between gas molecules cause broadening of the molecular absorption lines, which can be described by the Lorentzian function. In many cases, there will be both doppler broadening and collisional broadening, with the gas line broadening being determined by both. Therefore, the line shape of the gas line broadening described by the Forgt function Voigt can be obtained by the convolution of the Gaussian function and the Lorentzian function. The method comprises the following specific steps:
wherein phiDRepresenting the line broadening, phi, described by a Gaussian functionLRepresenting collisional broadening described by Lorentzian function, u representing the wavenumber of the Gaussian line, v representing the wavenumber of the Forgtt line, v0The central wave number, a, representing a Gaussian line shapevAnd w are dimensionless numbers, respectively expressed as:
thirdly, according to the description of the scattered light and the description of the line shape of the gas spectral line broadening, detection data corresponding to the backward scattered light are calculated. Specifically, when the tuned laser simultaneously generates the mie scattering, the rayleigh scattering, and the molecular absorption in the air, the parameter of the backscattered light (i.e., the detection data) is calculated by the following formula (4):
wherein, I0Denotes the incident light intensity, v denotes the wave number of the incident laser light, λ denotes the wavelength, r denotes the distance from the scattering point to the observation point, n denotes the refractive index, w denotes the mass concentration, ρ denotes the particle density, d denotes the average particle diameter of the particles, i denotes the particle diameter1(theta) and i2(θ) is a function of the polarization scattering intensity perpendicular and parallel to the scattering plane, respectively, and is a function related to the particle diameter d, refractive index n, and wavelength λ of the particles. The plane formed by the r axis and the Z axis is a scattering surface, and theta is a scattering angle. α (v) represents an absorption coefficient of a gas molecule, the absorption coefficient represents the unit concentration and the absorbance of the gas at the unit optical path length, and represents the absorption capacity of the gas molecule for light of different wave numbers, C represents the average concentration of the gas on the measurement path of the atmospheric data measurement system, and L represents the optical path length of the measurement path. Equation (4) includes multiple scattering and absorption processes, and the signals are extremely complex, but the characteristics of each signal are different. Mie scattering and Rayleigh scattering have different angular distributions and have insignificant wavelength characteristics, i.e., appear as broadband characteristics, while absorption appears as narrowband characteristics with wavelength. The separation of different signals is obtained by measuring and analyzing the spatial angle and wavelength characteristics of the received back scattering signals, and then the data such as particle density, molecular density, pressure, temperature, speed and the like carried in the signals can be calculated.
In one embodiment, the computer calculates the atmospheric data from the absorption line parameters by: first, the integrated absorbance is calculated by the following formula:
wherein A (v) represents the integrated absorbance of the gas molecule, It(v) Indicates the intensity of emitted light, I0(v) The method is characterized in that the method represents incident light intensity, alpha (v) represents a gas molecule absorption coefficient, P represents total pressure of a gas system, C represents average gas concentration on a measuring path, S (T) represents gas molecule absorption line intensity, L represents optical path length of the measuring path, and phi (v) is an absorption line linear function which is a normalization function, and the integral of the function is 1.
When the gas concentration is calculated, the gas concentration can be calculated according to the integral absorbance, the gas pressure, the measurement optical path length and the absorption line intensity. Specifically, the calculation is performed by the following formula:
wherein the meaning of the parameters is referred to equation (5).
When the atmospheric temperature is calculated, the particle number distribution of the molecular energy level meets the Boltzmann distribution under the thermodynamic equilibrium state, the line intensity of the absorption spectrum is related to the particle number of the corresponding energy level transition and the transition probability, and the size of the spectrum line intensity is only related to the temperature for a specific absorption spectrum line. Therefore, the temperature of the environment can be reflected within a certain temperature range by using two absorption lines of the same gas molecule. Since the integrated absorbance of the absorption spectrum is closely related to the pressure, the line intensity of the absorption spectrum, the molar concentration of the substance and the optical path length, the integrated absorbance of the two absorption spectrum lines are measured in the same environment, and the molar concentration, the pressure, the temperature and the optical path length of the substance are considered to be the same, the ratio of the integrated absorbance of the two absorption peaks can be simplified to the ratio of the line intensity, namely:
wherein A1 and A2 are the integrated absorbances, E ″, of the two absorption lines, respectively1、E″2Energy of low transition level, S, of two spectral lines respectively1(T0)、S2(T0) Respectively two spectral lines at a reference temperature T0Strong line of time, kBBoltzmann constant, and c is the speed of light in vacuum. In practice, the reference temperature T0Strong line of time S (T)0) May be obtained by a spectral database (HITRAN or HITEMP) query, or by experimental measurements.
When calculating atmospheric pressure, the gas pressure can be calculated according to the measured absorbance of the gas and the Lorentz broadening of the spectral line, and the calculation is specifically realized by the following formula:
wherein, Δ vcRepresenting the lorentz line width, and a represents the integrated absorbance of the gas.
When calculating the velocity, because of the gas flow of the air, the central frequency of the scattered light and the central frequency of the absorption spectrum both generate doppler shift, and the relationship between the gas molecular motion velocity V and the doppler shift is:
wherein λ is the central wavelength of the laser, Δ fDFor the doppler shift, θ is the angle between the laser beam and the direction of particle motion.
The scattering and molecular absorption in the air have Doppler effect, and can be used for air velocity measurement respectively, and a frequency discriminator is not needed when the air velocity is calculated through the absorption spectrum. And by simultaneously measuring the speed and comparing the speed measurement results of the two, mutual authentication can be realized, and a more accurate measurement result can be obtained. When the two are applied simultaneously, the method can also be used for measuring and diagnosing the turbulent flow structure of a complex flow field.
In calculating the atmospheric density, formula (4) may be expressed as I ═ M + R) I0. Wherein M represents the proportion of the meter scattering in the total scattered energy, and R represents the proportion of the rayleigh scattering in the total scattered energy. Through the calculation of M and R under different scattering angles and scattering distances, the proportion of the Mie scattering and the Rayleigh scattering at the laser wavelength of 760nm can be obtained, and the atmospheric density can be obtained.
In addition, since the speed measurement accuracy and the pressure measurement accuracy of the absorption spectrum both depend on the spectral resolution and accuracy, the factors such as the laser linewidth, the spectral sampling bandwidth, and the laser scanning linearity, which may affect the spectral resolution, need to be analyzed comprehensively and designed strictly. If the laser power is low, the sensitivity of the detector and the signal-to-noise ratio of the signal can be increased to ensure the signal-to-noise ratio of the received signal and improve the quality of the detected signal.
In one embodiment, in order to improve the accuracy of the atmospheric data measurement, the tunable laser emits a plurality of tuning lasers with different wavelengths, and a plurality of corresponding gas molecule absorption spectral lines are obtained through the passband wavelength range of the optical filter. And then, after the computer respectively measures the atmospheric data according to the plurality of absorption spectral lines, the obtained atmospheric data can be mutually verified to determine the reliability of the measured atmospheric data. If the difference between the atmospheric data measured by the plurality of spectra is within a preset difference, the measured atmospheric data can be determined to have certain accuracy.
Further, the choice of spectral lines is important when making atmospheric data measurements, especially temperature measurements with dual spectral lines. The computer can select the absorption spectral lines according to preset spectral line selection conditions. The preset spectral line selection conditions comprise: first, the line intensity difference between the selected spectral line and other adjacent spectral lines should be greater than a preset value. The selected spectral lines are relatively independent, and no others are aroundStrong line interference, and relatively weak absorption of other adjacent lines, can accurately distinguish the lines from the measured absorption spectrum. Secondly, for the temperature measurement range, the air broadening coefficient of the spectral line needs to be larger than 0.04cm-1atm-1So as to ensure that the spectral line has larger width in the temperature range to be detected, and is more favorable for single spectral line temperature measurement. Thirdly, the temperature coefficient of the line-air broadening is as large as possible, at least larger than a preset value (e.g. 0.5), to ensure sufficient sensitivity of the line width to temperature variations. Fourthly, according to the measured ambient temperature, the low-level energy of the spectral line is considered in a targeted manner. When the ambient temperature is less than a preset value (such as below 2000K), the low-level energy should be less than 1000cm-1To ensure that there is sufficient population of particles.
In addition, after the absorption line spectrum is obtained, the wave number precision calibration and correction can be carried out on the absorption line spectrum, and the Gaussian filter function is adopted to filter the absorption line spectrum so as to reduce random noise. Thereafter, in order to evaluate the laser wavenumber accuracy, uncertainty analysis was performed.
The system simultaneously inverts a plurality of parameters of air such as density, oxygen concentration, air temperature, pressure, speed and the like by detecting a composite spectrum signal of atmospheric scattering and oxygen molecule absorption, thereby realizing synchronous measurement of a plurality of parameters of atmospheric data required by an aircraft. The method is not limited by the height and the speed of the aircraft, can obtain reliable backscattering signals at different heights, meets the requirement of large airspace application from the near ground to the near space, adapts to various different flight modes and environments, improves the reliability of atmospheric data measurement, improves the measurement precision, and is beneficial to guaranteeing the flight safety.
Fig. 3 is a flowchart of an atmospheric data measurement method according to an embodiment of the present application, which specifically includes the following steps:
s301: the waveform of the tuned laser is generated by a signal generator.
S302: and emitting tuning laser with corresponding wavelength by the tunable laser to irradiate the air.
S303: and an optical lens group is adopted to receive the back scattered light of the tuned laser after the back scattered light and the absorbed light of the gas molecules.
And controlling the tuning laser to irradiate the air, wherein aerosol and gas molecules in the air have scattering and absorption effects on the tuning laser, so that corresponding backward scattering light can be obtained, and scattering and absorption information carried in the backward scattering light can be subsequently used for calculating atmospheric data.
S304: the backscattered light is converted into a corresponding electrical signal by a detector.
S305: and acquiring digital signals corresponding to the electric signals through a computer to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, and performing linear function fitting on the absorption spectral line shapes to obtain corresponding absorption spectral line parameters for calculating atmospheric data.
The nonlinear fitting LM algorithm is improved and called as AI-LM fitting algorithm, Voigt linear function fitting is carried out on the absorption spectral line shape, corresponding parameters of initial value assignment in the next iteration process are predicted according to the iteration fitting result and corresponding fitting parameters in the current iteration process, standard iteration initial values are determined through feedback iteration and serve as optimal iteration initial values, effective fitting of the multi-parameter nonlinear function is achieved, and corresponding absorption spectral line parameters are obtained. The method is not influenced by signal-to-noise ratio, interference and the like, and effectively solves the problems of large fitting error and fitting failure. The convolution of Lorentz and Gaussian line shapes according to Voigt line shape fitting can effectively remove some interference and errors to a certain extent, and the accuracy of a measurement result is improved, so that the measurement standard deviation is relatively small. And the Voigt linear fitting result is more stable, and the method can be used for calculating subsequent atmospheric data such as temperature.
Fig. 4 is a detailed flowchart corresponding to fig. 3 provided in an embodiment of the present application. As shown in fig. 4, the detector collects the electrical signals, and the electrical signals are calculated by the computer and introduced into the data processing software to be stored as the detection data in the form of matrix data. And then, selecting the light spot to be detected as data to be detected on the light path, carrying out cycle division on the data to be detected, and carrying out average processing to obtain the data to be detected in one cycle so as to reduce errors. And performing baseline fitting on the data to be measured in one period, and obtaining the linear shape of the absorption spectrum by using the Lambert beer law. And (4) performing wave number calibration and correction on the linear shape of the absorption spectrum, and filtering by adopting Gaussian filtering. And then carrying out AI-LM linear function fitting on the absorption spectrum line shape to obtain corresponding absorption spectrum parameters. And calculating to obtain corresponding integral absorbance according to the absorption spectrum parameters, and calculating to obtain corresponding atmospheric data.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (5)
1. An atmospheric data measurement system is characterized by comprising a laser light source, a detection unit and a computer;
the laser light source comprises a signal generator, a laser controller and a tunable laser; the signal generator is used for generating a waveform of tuned laser light, the laser controller is used for controlling the temperature and the injection current of the tunable laser, and the tunable laser is used for emitting the tuned laser light with corresponding wavelength;
the detection unit comprises an optical filter, an optical lens group and a detector; the optical filter filters stray light in the backward scattering light of the tuned laser after gas molecule scattering and absorption, the optical lens group is used for receiving the filtered backward scattering light, and the detector is an array type, image type or single-point type photoelectric conversion device and is used for converting the backward scattering light into a corresponding electric signal through photoelectric conversion;
the computer is used for acquiring digital signals corresponding to the electric signals to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, and performing linear function fitting on the absorption spectral line shapes to obtain corresponding absorption spectral line parameters for calculating atmospheric data;
the computer is specifically configured to describe, according to scattering information carried in the detection data, corresponding scattered light by using a mie scattering model or a rayleigh scattering model, describe, according to absorption information carried in the detection data, a fogter function obtained by convolution of a gaussian function and a lorentz function, and describe a line shape of a broadened gas absorption spectrum line, and calculate, according to the description of the scattered light and the description of the line shape of the broadened gas absorption spectrum line, detection data corresponding to the backscattered light.
2. The system of claim 1, wherein the computer is specifically configured to calculate an integrated absorbance from the absorption line parameter;
calculating to obtain corresponding air flow velocity according to the Doppler frequency shift of the central frequency of the absorption spectral line;
calculating to obtain the atmospheric temperature according to the corresponding absorption spectrum line pair, the integral absorbance of the absorption spectrum line pair and the line intensity at the reference temperature;
calculating to obtain gas pressure according to the integral absorbance, the measured optical path length and the Lorentz line width of an absorption spectral line;
and calculating to obtain the gas concentration according to the integral absorbance, the gas pressure, the measuring optical path length and the line intensity of the absorption spectrum.
3. The system according to claim 1, wherein the tunable laser is specifically configured to emit tuned laser light of a corresponding wavelength according to a preset period;
the computer is specifically configured to acquire periodic detection data, select data to be detected belonging to different periods from the detection data, and perform averaging and filtering processing.
4. The system of claim 1, wherein the computer is specifically configured to measure the atmospheric data from a first direction, a second direction, and a third direction, respectively, and to mutually authenticate corresponding measurements; the first direction, the second direction and the third direction are mutually vertical.
5. An atmospheric data measurement method, comprising:
generating a waveform of the tuned laser by a signal generator;
emitting tuning laser with corresponding wavelength by a tunable laser to irradiate the air;
an optical lens group is adopted to receive the back scattered light of the tuned laser after the back scattered light and the absorbed light of the gas molecules;
converting the backscattered light into a corresponding electrical signal by a detector;
acquiring digital signals corresponding to the electric signals through a computer to obtain detection data, performing baseline fitting on the detection data to obtain corresponding absorption spectral line shapes, and performing linear function fitting on the absorption spectral line shapes to obtain corresponding absorption spectral line parameters for calculating atmospheric data;
and describing, by the computer, the corresponding scattered light by respectively adopting a meter scattering model or a Rayleigh scattering model according to scattering information carried in the detection data, describing the line shape of the broadening of the gas absorption spectrum by adopting a Forgter function obtained by convolution of a Gaussian function and a Lorentz function according to absorption information carried in the detection data, and calculating the detection data corresponding to the backward scattered light according to the description of the scattered light and the description of the line shape of the broadening of the gas absorption spectrum.
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