All-sky background radiometer full-channel calibration method based on spectrum inversion

Abstract

The invention discloses an all-sky background radiometer full-channel calibration method based on spectral inversion, and the method comprises the steps: obtaining a discrete response value of a non-absorption wave band of an all-sky background radiometer based on solar direct radiation and a Langley calibration method in combination with the solar irradiance of an atmospheric boundary layer, the atmospheric relative quality and a sun-ground distance correction factor; a solar direct radiation and gas absorption calibration method is utilized, a gas absorption effect is considered, and a discrete response value of an absorption wave band is calculated through inversion of the total amount of water vapor; determining a full-band discrete irradiance calibration coefficient based on the discrete response values of the non-absorption band and the absorption band; fitting by using the full-band discrete irradiance calibration coefficient and adopting an interpolation algorithm to obtain a full-band instrument irradiance calibration function; and transmitting an instrument irradiance calibration function to the direct incidence channel and the scattering channel, and obtaining radiance calibration coefficients of the direct incidence channel and the scattering channel in combination with the field angle and the attenuation coefficient of the optical filter, thereby completing full-channel calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical radiation measurement and calibration, and in particular to a full-channel calibration method for a full-sky background radiometer in the 300-1700nm band range, which can be widely applied to the field of accurate measurement of full-sky background radiation in atmospheric optical monitoring, environmental remote sensing and related scientific research and industrial fields. BACKGROUND

[0002] The spectral sky background radiometer generally has three measurement modes: direct sunlight channel measurement, sun-scattered channel point observation, and sun-scattered channel full-sky observation. From the perspective of measurement channels, it is mainly divided into direct channel and scattered channel. In the prior art, Langley calibration method is generally used for direct channel calibration. This method is based on the characteristics of relatively stable extraterrestrial solar irradiance in a short time. By measuring the solar irradiance reaching the ground under different atmospheric quality, the Beer-Bouguer-Lambert law is used to invert the atmospheric optical thickness and other parameters, and then the calibration coefficient of the radiometer in the non-absorption band is determined. The laboratory standard light source method is used for scattered channel calibration, that is, in the laboratory environment, the scattered channel is calibrated using a standard light source that has been strictly calibrated. By measuring the response of the standard light source in the scattered channel, a quantitative relationship between the output of the radiometer and the actual brightness is established.

[0003] Limitations of Langley calibration method: Langley calibration method relies on the accurate known extraterrestrial solar irradiance and the accuracy of atmospheric transmission model. In actual application, this method can only obtain relatively accurate calibration results in the non-absorption band. When it involves water vapor absorption band (such as near 936nm, 1100nm, 1400nm), oxygen absorption band and other bands with strong gas absorption, due to the complexity of atmospheric absorption, the existing atmospheric transmission model cannot accurately describe the radiation transmission process, resulting in a serious decline in calibration accuracy, which cannot meet the actual measurement requirements. Disadvantages of laboratory standard light source method: The laboratory standard light source method requires extremely strict calibration environment, which needs to be carried out in a laboratory with strictly controlled temperature, humidity, air pressure and other environmental parameters to ensure the stability and accuracy of the standard light source. At the same time, the calibration of the standard light source itself also requires professional equipment and complex operation process, which is high in cost. This makes the method greatly limited in actual outdoor measurement and calibration, especially for full-sky background radiometers that need to be observed continuously in the field for a long time. The scattered channel cannot be calibrated in real time at the observation site, which leads to the drift of the measurement results due to instrument aging, environmental changes and other factors during long-term observation, and cannot guarantee the long-term accuracy and reliability of the data.

[0004] Due to the above defects of the existing calibration method, the scattering channel of the spectral sky background radiometer as an important field observation equipment is difficult to be effectively calibrated in the complex outdoor environment. This seriously affects the accuracy and reliability of the overall measurement data of the radiometer in actual application, especially in long-term observation in extreme environments (such as polar regions and high-altitude areas), and cannot provide high-quality data support for atmospheric optical research, environmental monitoring and other fields, thereby restricting the development of related fields. SUMMARY

[0005] The purpose of the present application is to provide a full-channel calibration method for a full-sky background radiometer based on spectral inversion, which overcomes the problem that the scattering channel calibration of the full-sky background radiometer in the prior art depends on the laboratory environment and is invalid in the absorption band, effectively improves the calibration accuracy and data reliability of the radiometer, and better meets the demand for high-precision measurement of the full-sky background radiometer in the field of atmospheric optical monitoring.

[0006] In order to achieve the above task, the present application adopts the following technical solutions: The full-channel calibration method for the full-sky background radiometer based on spectral inversion comprises: Based on the solar direct radiation and the Langley calibration method, and combined with the atmospheric boundary layer solar irradiance and the atmospheric relative mass and the distance correction factor between the earth and the sun, the discrete response value of the non-absorption band of the full-sky background radiometer is obtained; Using the solar direct radiation and the gas absorption calibration method and considering the gas absorption effect, the discrete response value of the absorption band is calculated by inverting the total amount of water vapor; Based on the discrete response values of the non-absorption band and the absorption band, the full-band discrete irradiance calibration coefficient is determined; the full-band instrument irradiance calibration function is obtained by fitting using the interpolation algorithm with the full-band discrete irradiance calibration coefficient; The instrument irradiance calibration function is transmitted to the direct channel and the scattering channel, and combined with the field of view angle and the attenuation coefficient of the optical filter, the radiance calibration coefficient of the direct channel and the scattering channel is obtained, and the full-channel calibration is completed; The actual measurement value of the full-sky background radiometer in the direct channel and the scattering channel is used to obtain the radiance value of the direct channel and the scattering channel through the radiance calibration coefficient.

[0007] Further, in the non-absorption band, the direct channel is observed, and the actual measurement value of the solar spectrum reaching the ground measured by the full-sky background radiometer is is:

[0008] In the above formula, is the discrete irradiance calibration coefficient of the full-sky background radiometer; Solar irradiance in the atmospheric boundary layer. This is the Earth-Sun distance correction factor. The relative mass of the atmosphere; The atmospheric optical thickness along the vertical path; It is a natural exponential function; atmospheric relative mass The solar zenith angle θ changes; under clear weather conditions, the all-sky background radiometer continuously observes the sun to obtain different results. Actual measured value under the value Obtained through linear fitting and The fitting relationship between them will include the relative atmospheric mass in the fitting relationship. When set to 0, the actual measured value at this time That is, relative to the outside of the atmospheric boundary layer Corresponding discrete response value .

[0009] Furthermore, in the gas absorption band, the actual measured values ​​of the solar spectrum reaching the ground obtained by the all-sky background radiometer. It can be represented as:

[0010] in The gas absorption coefficient; when the atmospheric optical relative mass... When it is 0, at this time The value is relative to the area outside the atmospheric boundary layer. Wavelength response value after gas absorption .

[0011] Furthermore, atmospheric optical thickness was obtained in the non-absorption band using the Langley calibration method. Using an inversion algorithm based on water vapor absorption to... Converted to total water vapor :

[0012] Fitting parameters were obtained by combining atmospheric models and measured data. ; The total amount of water vapor will be calculated. Substituting into the following formula, the water vapor transmission rate can be obtained. :

[0013] Use wavelength response values ​​for the absorption band Perform gas absorption correction:

[0014] At this time The value refers to the absorption band of the all-sky background radiometer under conditions of no atmospheric interference. The discrete response value.

[0015] Furthermore, after obtaining the discrete response values ​​for the non-absorption and absorption bands, the discrete response values ​​of the all-sky background radiometer across the entire 300-1700 nm wavelength range were constructed. Then we have:

[0016] The corresponding full-band discrete irradiance calibration coefficients can be obtained through calculation:

[0017] For all-sky background radiometers, the full-band discrete irradiance calibration factor Within a certain range, it can be considered a continuously changing linear function. Therefore, by continuously adjusting the discrete irradiance calibration coefficients across the entire band... Interpolation yields the instrument irradiance calibration function for the entire spectral band. .

[0018] Furthermore, assuming the actual measured values ​​of each channel obtained by the all-sky background radiometer at the Earth's surface are... Then, through the instrument's irradiance calibration function This voltage value can then be converted into an irradiance value. .

[0019] Furthermore, given the known irradiance calibration function of the all-sky background radiometer... and In this case, the radiance calibration coefficient of the direct channel of the all-sky background radiometer can be calculated by the following formula:

[0020] In actual measurements, the only difference between the direct channel and the scattered channel in terms of optical transfer function is the filter; the radiance calibration coefficient of the direct channel is... Radiance scaling factor converted to scattering channel :

[0021] in is the attenuation coefficient of the filter.

[0022] Furthermore, assuming that the actual measured values ​​of the direct and scattered channels obtained by the all-sky background radiometer at the Earth's surface are... Then, through the instrument's radiance calibration coefficient or This voltage value can be converted into a radiance value : Or .

[0023] A terminal device comprising a processor, a memory, and a computer program stored in the memory; the processor implements the full channel calibration method of the sky background radiation meter based on spectral inversion when executing the computer program.

[0024] A computer readable storage medium, the medium stores a computer program; the computer program is executed by a processor to implement the full channel calibration method of the sky background radiation meter based on spectral inversion.

[0025] Compared with the prior art, the present application has the following technical characteristics: 1. Overcome the calibration problem in the absorption band: the present application innovatively combines the gas absorption calibration method, fully considers the influence of gas absorption on solar radiation transmission, effectively breaks through the limitations of Langley calibration method in the absorption band, and successfully realizes accurate and reliable calibration in the full waveband range of 300-1700nm, providing key technical support for high-precision measurement of the sky background radiation meter in complex atmospheric environment. 2. Break away from the shackles of laboratory environment: cleverly use solar radiation as a stable and natural radiation source, and accurately transfer the calibration results of the direct channel to the scattering channel by deeply studying the optical transfer function relationship between the direct channel and the scattering channel, realizing the outdoor observation calibration of the full channel of the sky background radiation meter. This breakthrough completely breaks the strict requirements of the traditional laboratory standard light source method on the calibration environment, greatly improving the calibration flexibility and practicality of the radiometer in complex environment. 3. Significantly improve the applicability in complex environment: the calibration method can complete the full channel calibration of the sky background radiation meter in real time and quickly in the field, effectively overcoming the problem that the traditional calibration method is difficult to implement in extreme environment (such as low temperature in winter polar region, low pressure in high altitude area, etc.). This makes the reliability of long-term observation data of the radiometer in complex environment significantly improved, providing strong data guarantee for the research and application of atmospheric optical monitoring, environmental remote sensing and other fields in extreme environment, and promoting the further development of related fields. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the method of the present application is shown; Figure 2 The schematic diagram of the channel structure of the sky background radiation meter is shown. DETAILED DESCRIPTION

[0027] This invention provides a full-channel calibration method for all-sky background radiometers based on spectral inversion. It aims to address the difficulty of calibrating the scattering channels of existing spectral sky background radiometers in outdoor observations, which rely heavily on laboratory light sources. This method achieves high-precision calibration of the all-sky background radiometer across the entire 300-1700 nm wavelength range, covering both direct and scattering channels. This significantly improves the reliability and stability of long-term measurement data under complex environments, meeting the urgent needs of atmospheric optical monitoring, environmental remote sensing, and other fields for high-precision all-sky background radiation measurements. The successful completion of full-channel calibration is marked by the successful solution of the following two core parameters: Discrete response value : Represents the instrument response value corresponding to solar irradiance outside the atmosphere, used for radiation calibration of the direct sunlight channel; radiance calibration coefficient of the direct sunlight channel. : Obtained through direct channel parameter transfer, used for radiance calibration of the scattering channel.

[0028] Once these parameters are calculated and verified through the calibration process, the full-channel calibration is considered complete. This invention provides a full-channel calibration method for all-sky background radiometers based on spectral inversion. From calculating the response values ​​of the non-absorbing and absorbing bands, to fitting the full-band response values, and then to the transfer of calibration coefficients between the direct and scattered channels, it comprehensively and efficiently solves the problem of full-channel calibration for all-sky background radiometers. This invention includes the following steps: Step 1: Based on direct solar radiation and the Langley calibration method, the discrete response values ​​of the non-absorption band of the all-sky background radiometer are obtained by using the Beer-Bouguer-Lambert law and combining atmospheric boundary layer solar irradiance, atmospheric relative mass, and Sun-Earth distance correction factors.

[0029] Solar irradiance received by the atmospheric boundary layer It fluctuates only slightly over a short period of time, and can be considered a standard value; the solar irradiance of the atmospheric boundary layer with wavelength λ. After absorption and scattering in the atmosphere, the remaining radiant energy reaching the ground follows the Beer-Bouguer-Lambert law: Formula 1 in Solar irradiance in the atmospheric boundary layer is obtained through theoretical models or standardized data sources; This represents the solar irradiance received by the ground. This is the Earth-Sun distance correction factor, used to correct the impact of changes in the Earth-Sun distance caused by the Earth's revolution on solar irradiance; The relative mass of the atmosphere; The atmospheric optical thickness along the vertical path; is a natural exponential function. Atmospheric optical thickness is a dimensionless number, which represents the total weakening of the radiation caused by all absorption and scattering effects along the unit cross section of the radiation transmission path. is the ratio of the actual path length of the sunlight through the earth's atmosphere to the path length in the vertical direction (when the zenith angle is 0°).

[0030] is the actual measurement value of the ground-based sky brightness radiometer. is a voltage signal, whose value is proportional to the solar irradiance received by the ground; therefore, it is assumed that is the response value of the ground-based sky brightness radiometer to the atmospheric boundary layer solar irradiance in practical applications, then equation 1 can be written as: Equation 2 Therefore, after the completion of the calibration of the ground-based sky brightness radiometer, the total optical thickness containing the data can be calculated by the actual measurement value .

[0031] In the non-absorption waveband (e.g., the visible light waveband of 400-700 nm) in the range of 300-1700 nm, the actual measurement value of the solar spectrum reaching the ground measured by the ground-based sky brightness radiometer in the direct channel is: Equation 3 In the above equation, is the discrete irradiance calibration coefficient of the ground-based sky brightness radiometer; at this time, the atmospheric relative mass is changed by changing the solar zenith angle θ, that is, in the case of fine weather, the ground-based sky brightness radiometer continuously observes the sun to obtain data at different values, and the fitting relationship between and is obtained by linear fitting. When the atmospheric relative mass in the fitting relationship is set to 0, the actual measurement value at this time is the corresponding discrete response value of the non-absorption waveband relative to the atmospheric boundary layer outside .

[0032] Step 2: Using the solar direct radiation and gas absorption calibration method and considering the gas absorption effect, the discrete response value of the absorption waveband is calculated by inverting the total amount of water vapor.

[0033] ​​​​​In the gas absorption band, since there are multiple absorption bands for a single gas in the 300-1700nm range (such as around 936nm, 1100nm, and 1400nm), it can be represented as: Formula 4 When atmospheric optical relative mass When it is 0, at this time The value is relative to the area outside the atmospheric boundary layer. Wavelength response value after gas absorption Due to the same gas absorption coefficient under the same measurement conditions It is only related to concentration, optical path and absorption coefficient. Taking water vapor as an example, its absorption peaks exist near 936nm, 1100nm and 1400nm. The absorption of water vapor in this band is known.

[0034] Atmospheric optical thickness obtained by Langley calibration in the non-absorption band Using empirical models (such as inversion algorithms based on water vapor absorption) to... Converted to total water vapor : Formula 5 In practice, parameters need to be fitted by combining atmospheric models and measured data. .

[0035] The total amount of water vapor will be calculated. Substituting into equation 7 below, the water vapor transmission rate can be obtained. : Formula 6 Use wavelength response values ​​for the absorption band (for Gas absorption correction is applied to ground-measured values ​​>0. Formula 7 At this time The value is the value of the all-sky background radiometer when there is no atmospheric interference in the absorption band. The discrete response value.

[0036] Similarly, discrete response values ​​for different absorption bands can be obtained for other gas absorption bands.

[0037] Step 3: Based on the discrete response values ​​of the non-absorbing and absorbing bands, determine the discrete irradiance calibration coefficients for the entire band; using the discrete irradiance calibration coefficients for the entire band, use an interpolation algorithm to fit the data to obtain the instrument irradiance calibration function for the entire band.

[0038] Steps 1 and 2 yielded discrete response values ​​for the non-absorption and absorption bands, thus forming the discrete response values ​​of the all-sky background radiometer across the 300-1700 nm wavelength range. Then we have: Formula 8 The corresponding full-band discrete irradiance calibration coefficients can be obtained through calculation: Formula 9 For all-sky background radiometers, the full-band discrete irradiance calibration factor Within a certain range, it can be considered a continuously changing linear function. Therefore, by continuously adjusting the discrete irradiance calibration coefficients across the entire band... Interpolation yields the instrument irradiance calibration function for the entire spectral band: Formula 10 in, These are the parameters for linear fitting.

[0039] In the process of spectral data processing, to achieve smooth data transition and accurate reconstruction, this invention employs interpolation algorithms to process discrete data points. Specifically, the interpolation algorithm chosen is either cubic spline interpolation or polynomial interpolation. Cubic spline interpolation, by constructing a piecewise cubic polynomial and ensuring the continuity of function values, first derivatives, and second derivatives between segments, effectively avoids the Runge phenomenon and exhibits good stability and smoothness when processing complex spectral curves. Polynomial interpolation, on the other hand, determines the polynomial order based on the number of data points and fits the optimal polynomial function using the least squares method. In scenarios with limited data and relatively simple spectral curves, it can quickly and accurately perform data interpolation, meeting the stringent requirements of full-channel calibration for data integrity and continuity. By appropriately selecting the interpolation algorithm, not only can the discreteness of spectral data be effectively handled, but a high-quality data foundation is also provided for subsequent data acquisition and preprocessing, calibration result verification, and other steps, ensuring the coherence and scientific rigor of the entire calibration process.

[0040] For example, suppose the voltage values ​​of each channel measured by the all-sky background radiometer at the Earth's surface are... Then, through the instrument's irradiance calibration function This voltage value can then be converted into an irradiance value. .

[0041] Formula 11 Step 4: Transfer the instrument irradiance calibration function to the direct and scattered channels. Combine the field of view and the attenuation coefficient of the filter to obtain the irradiance calibration coefficients of the direct and scattered channels, and complete the full-channel calibration. Based on the actual measurement values ​​of the all-sky background radiometer in the direct and scattered channels, the irradiance values ​​of the direct and scattered channels can be obtained using the irradiance calibration coefficients.

[0042] In actual measurements, the conversion between radiance and irradiance is achieved by dividing the irradiance measurement by the current field of view of the all-sky background radiometer. Given the irradiance calibration function of the all-sky background radiometer and In this case, the radiance calibration coefficient of the direct channel of the all-sky background radiometer can be calculated by Equation 10: Formula 12 In actual measurements, the only difference between the direct-view channel and the scattering channel in terms of optical transfer function is the use of filters. The direct-view channel has a filter, while the scattering channel does not. Therefore, at a known field of view... In this case, the direct channel radiance calibration coefficient can be calculated using Equation 11. Radiance scaling factor converted to scattering channel .

[0043] Formula 13 in is the attenuation coefficient of the filter.

[0044] For example, suppose the actual measured values ​​of the direct and scattered channels obtained by the all-sky background radiometer at the Earth's surface are... Then, through the instrument's radiance calibration coefficient or This voltage value can then be converted into a radiance value. : or

[0045] Calibration result verification: Select a high-precision blackbody radiation source with known spectral radiance or other authoritative calibration standard radiation source, and use the calibrated all-sky background radiometer to perform multiple measurements. Compare the measurement results with the standard values, calculate the absolute error and relative error, and evaluate the calibration effect. If the error exceeds the allowable range, check each step of the calibration process and adjust the parameters or recalibrate.

[0046] This invention breaks through the limitations of traditional calibration methods in absorption bands and outdoor calibration scenarios, and can achieve high-precision and high-efficiency calibration of all-sky background radiometers in the full band of 300-1700nm. It has the characteristics of high calibration accuracy and strong environmental adaptability.

[0047] Example: (1) Data acquisition preparation: Before calibration, the all-sky background radiometer is fully inspected and debugged, and installed and debugged at the observation site; ensure that the parameters of the all-sky background radiometer are set correctly and the working status is stable; at the same time, prepare auxiliary equipment for measuring environmental parameters such as atmospheric relative mass and Earth-Sun distance, such as solar photometers and weather stations; and ensure that their measurement accuracy meets the requirements.

[0048] Based on the observation mission and environmental conditions, the observation parameters of the all-sky background radiometer should be set appropriately, including spectral sampling interval, integration time, and observation time interval. This ensures that high-quality spectral data can be acquired under different weather and lighting conditions. During data acquisition and preprocessing, strict adherence to operating procedures is essential. Regular equipment maintenance is crucial to ensure the reliability and stability of the acquired data. A data backup mechanism must be established to prevent data loss from affecting the accuracy and completeness of the calibration work. Furthermore, detailed experimental records must be maintained throughout the calibration process, accurately documenting each step of the operation, measurement data, and processing results for subsequent traceability and analysis. Additionally, the observation frequency and calibration cycle can be adjusted appropriately for different climatic conditions and observation scenarios to ensure the long-term stable and accurate operation of the all-sky background radiometer.

[0049] (2) Direct Sun Channel Observation: Continuous and high-precision observations of direct solar radiation are conducted using the direct sun channel of the all-sky background radiometer. Actual measurements are collected at set time intervals, and environmental parameters such as observation time, atmospheric relative mass, and Earth-Sun distance correction factor are recorded simultaneously. During data acquisition, the instrument's operating status is closely monitored to ensure data integrity and accuracy. The collected raw data undergoes preprocessing, including outlier removal, dark current subtraction, and detector response inhomogeneity correction. Data smoothing and filtering algorithms are used to reduce the impact of noise on the data, improving data quality and stability.

[0050] (3) Environmental parameter measurement: Environmental parameters such as atmospheric relative mass and Earth-Sun distance correction factor are measured in real time using professional meteorological instruments and astronomical observation equipment. These parameters will serve as important inputs for subsequent calibration calculations, ensuring the accuracy and reliability of the calibration results.

[0051] (4) Non-absorption band processing: In the 300-1700nm spectral range, select representative non-absorption bands, such as the visible light band (400-700nm). These bands are less affected by atmospheric absorption and are suitable for calibration using the Langley calibration method.

[0052] Based on the collected environmental parameters and combined with Formula 3 in Step 1, multiple sets of data were collected at different times and under different atmospheric conditions to construct a system of linear equations. The system of linear equations was solved using data fitting algorithms such as the least squares method to obtain the discrete response values ​​of the non-absorption band.

[0053] (5) Absorption band processing: Key absorption bands such as the water vapor absorption bands (around 936nm, 1100nm, and 1400nm) are calibrated. These bands are sensitive to changes in atmospheric water vapor content, and accurate calibration is of great significance for atmospheric optics research and environmental monitoring.

[0054] For the data in the absorption band, firstly, based on the atmospheric optical thickness and other information obtained from the calibration of the non-absorption band, and combined with the gas absorption model, parameters such as the total water vapor volume along the vertical path are calculated; finally, the discrete response value of the absorption band is obtained through the formula in step 2.

[0055] (6) Full-band response fitting: Using the discrete response values ​​of the non-absorbing and absorbing bands as input, and comprehensively considering the characteristics of the instrument response function and the distribution of the discrete response values, a suitable interpolation algorithm (such as cubic spline interpolation) is selected for fitting; through calculation, a continuous full-band instrument irradiance calibration function is constructed. The cubic spline interpolation algorithm can maintain the continuity and smoothness of the response function while ensuring fitting accuracy. During the fitting process, interpolation nodes and boundary conditions were appropriately set to ensure that the fitting results accurately reflected the instrument's response characteristics across the entire 300-1700 nm wavelength range. A continuous instrument irradiance calibration function was constructed through calculation. .

[0056] (7) Determination of the radiance calibration coefficient of the direct channel: Based on the instrument irradiance calibration function obtained by fitting, the radiance calibration coefficient of the direct channel in the entire 300-1700nm band is calculated.

[0057] (8) Transfer of radiance calibration coefficients of the scattering channel: Based on the optical transfer function relationship between the direct channel and the scattering channel, as well as the known filter attenuation coefficient and instrument field of view, the radiance calibration coefficients of the direct channel are converted into the radiance calibration coefficients of the scattering channel to complete the calibration of the scattering channel.

[0058] Following the steps outlined above, the full-channel calibration of the all-sky background radiometer was successfully completed. The calibration results were comprehensively checked and verified to ensure that the calibration accuracy met design requirements. A calibration result report was output to provide accurate calibration parameters for subsequent radiation measurements.

[0059] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A full-sky background radiometer full-channel calibration method based on spectral inversion, characterized in that, The method comprises the following steps: Based on the direct solar radiation and Langley calibration method, combined with the atmospheric boundary layer solar radiation and the atmospheric relative mass and the distance correction factor, the discrete response value of the non-absorption band of the all-sky background radiometer is obtained; Using the direct solar radiation and gas absorption calibration method and considering the gas absorption effect, the discrete response value of the absorption band is calculated by inverting the total amount of water vapor; Based on the discrete response values of the non-absorption band and the absorption band, the full-band discrete irradiance calibration coefficient is determined; the full-band instrument irradiance calibration function is obtained by using the full-band discrete irradiance calibration coefficient and adopting the interpolation algorithm for fitting; The instrument irradiance calibration function is transmitted to the direct channel and the scattering channel, combined with the field angle and the attenuation coefficient of the filter, the radiance calibration coefficient of the direct channel and the scattering channel is obtained, and the full-channel calibration is completed; The actual measurement values of the all-sky background radiometer in the direct channel and the scattering channel are used to obtain the radiance values of the direct channel and the scattering channel through the radiance calibration coefficient.

2. The full-sky background radiometer full-channel calibration method based on spectral inversion according to claim 1, characterized in that, In the non-absorbing wavelength range, the actual measured value of the solar spectrum reaching the ground obtained by measuring the sky background radiation in the direct channel is: in the above formulae, is the discrete irradiance scaling factor for the all-sky background radiometer; is the atmospheric boundary layer solar irradiance, is the earth-sun distance correction factor, is the relative air mass of the atmosphere; is the optical thickness of the atmosphere along the vertical path; is the natural exponential function; atmospheric relative mass The solar zenith angle θ changes; under clear weather conditions, the all-sky background radiometer continuously observes the sun to obtain different results. Actual measured value under the value Obtained through linear fitting and The fitting relationship between them will include the relative atmospheric mass in the fitting relationship. When set to 0, the actual measured value at this time That is, relative to the outside of the atmospheric boundary layer Corresponding discrete response value .

3. The full-sky background radiometer full-channel calibration method based on spectral inversion according to claim 1, characterized in that, In the gas absorption band, the actual measured value of the solar spectrum reaching the ground obtained by measuring the whole sky background radiation may be expressed as: wherein is the gas absorption coefficient; when the atmospheric optical relative mass is 0, at which time the value is the relative to the outside of the atmospheric boundary layer corresponding to the wavelength response value after the gas absorption .

4. The full-sky background radiometer full-channel calibration method based on spectral inversion according to claim 1, characterized in that, The atmospheric optical thickness in the non-absorption band is obtained by Langley calibration method , and the total water vapor content is converted from the atmospheric optical thickness by using the inversion algorithm based on water vapor absorption . : Fitting parameters are obtained in combination with an atmospheric model and measured data ; The total amount of water vapor is calculated Substituting into the following equation, the water vapor transmission rate can be obtained : using wavelength response values for the absorption band performing gas absorption correction: At this time The value is the discrete response value of the total sky background radiation meter in the absorption band without atmospheric interference. of the total sky background radiation meter in the absorption band without atmospheric interference.

5. The full-sky background radiometer full-channel calibration method based on spectral retrieval according to claim 1, characterized in that, After the discrete response values of non-absorption band and absorption band are obtained, the discrete response values corresponding to the full band of 300-1700nm of the full sky background radiation meter are constituted ; then The corresponding full-band discrete irradiance calibration coefficient can be obtained by calculation: Full band discrete irradiance calibration coefficient for all-sky background radiometer In a certain range, it can be regarded as a linear function of continuous change, so by continuously Interpolation can obtain the corresponding full-band instrument irradiance calibration function .

6. The full-sky background radiometer full-channel calibration method based on spectral retrieval of claim 1, wherein, Assuming the actual measured value of each channel measured by the sky- brightness radiometer at the surface is then the irradiance calibration function of the instrument can be used to convert this voltage value to an irradiance value .

7. The full-sky background radiometer full-channel calibration method based on spectral retrieval of claim 1, wherein, In the case where the total sky background radiometer irradiance calibration function and The radiance calibration coefficient of the direct channel of the total sky background radiometer can be calculated from the following equation: In actual measurement, the direct channel and the scattering channel only have the difference of the filter in the optical transfer function; Direct channel radiance scaling factor Conversion to diffuse channel radiance scaling factor : wherein is the attenuation coefficient of the filter.

8. The full-sky background radiometer full-channel calibration method based on spectral retrieval of claim 1, wherein, Assuming that the actual measured values of the direct channel, the diffuse channel, measured by the sky brightness radiometer at the surface are , then by the radiance calibration factor of the instrument or one can convert this voltage value into a radiance value : or . 9.A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes the computer program, the full-channel calibration method based on spectral inversion of the all-sky background radiometer is realized.

10. A computer readable storage medium having stored therein a computer program; characterized in that, When the computer program is executed by the processor, the full-channel calibration method based on spectral inversion of the all-sky background radiometer is realized.

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