Standard number: QX/T 533-2019
Standard name: Technical specifications for sun photometer calibration
English name: Technical specifications for sun photometer calibration ||
tt||Standard format: PDF
Release time: 2019-12-26
Implementation time: 2020-04-01
Standard size: 1.04M
Standard introduction: This standard specifies the calibration technical indicators of sun photometers, the principle, composition and wavelength range of observation instruments, calibration conditions, calibration contents and methods, data archiving and calibration cycle
This standard is applicable to the regular calibration of sun photometers such as CE318-VBS8, CE-318NS9, CE318NP9 polarization, CE-318TS9, CE-318TP9, etc. The calibration of other types of sun photometers can be used as a reference.
2 Normative references
The following documents are indispensable for the application of this document. For any dated reference, only the dated version applies to this document. For any undated reference, the latest version (including all amendments) applies to this document
QX/T270—2015CE318 Sun photometer observation procedures
3 Terms and definitions
The following terms and definitions apply to this document
Multi- wavelength sun photometer
An instrument that measures the radiation signal intensity of the sun and sky at different wavelengths from visible light to near-infrared, at different zenith angles, and at different times, and inverts the optical depth of atmospheric aerosols and other characteristics.
[QX/T20-2015, Definition 2.3] This standard was drafted in accordance with the rules given in GB/T1.1-2009
This standard was proposed and managed by the Sub-Technical Committee on Atmospheric Composition Observation, Forecast and Warning Services of the National Technical Committee for Climate and Climate Change Standardization (SACTC540/SC1)
Drafting units of this standard: China Meteorological Science Academy, Meteorological Observation Center of China Meteorological Administration Main drafters of this standard: Che Huizheng, Zhang Xiaoye, Zhang Xiaochun, Zheng Yu, Lu Sai, Li Xiaopan
This standard specifies the calibration technical indicators of sunphotometers, the principle, composition and wavelength range of observation instruments, calibration conditions, calibration content and methods, data archiving and calibration cycle. This standard is applicable to the regular calibration of sun photometers of models such as CE318-VBS8, CE-318NS9, CE-318NP9 polarization, CE-318TS9, CE-318TP9, etc. The calibration of other types of sun photometers can be used as a reference.

ICS07.060
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Meteorological Industry Standard of the People's Republic of China
QX/T533—2019
Technical specifications for sun photometer calibration
Technical specifications for sun photometer calibration2019-12-26Release
China Meteorological Administration
Implementation on 2020-04-01
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Normative reference documents
Terms and definitions
Calibration technical indicators
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Observation instrument principle, composition and wavelength range·6
Calibration conditions||tt ||Calibration content and methods
Data archiving
Calibration cycle
Appendix A (Informative Appendix)
References
Sunlight meter calibration record form template
QX/T533—2019
QX/T533-2019
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This standard was drafted in accordance with the rules given in GB/T1.1—2009. This standard was proposed and managed by the Atmospheric Composition Observation, Forecast and Warning Service Sub-Technical Committee of the National Technical Committee for Climate and Climate Change Standardization (SACTC540/SC1).
Drafting units of this standard: China Meteorological Science Research Institute, Meteorological Observation Center of China Meteorological Administration. The main drafters of this standard: Che Huizheng, Zhang Xiaoye, Zhang Xiaochun, Zheng Yu, Lu Sai, Li Xiaopan. 1 Scope
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Calibration Technical Specifications for Sun Photometers
QX/T533—2019
This standard specifies the calibration technical indicators of sun photometers, the principle, composition and wavelength range of observation instruments, calibration conditions, calibration contents and methods, data archiving and calibration cycles.
This standard applies to the regular calibration of sun photometers of models such as CE318-VBS8, CE-318NS9, CE-318NP9 polarization, CE-318TS9, CE-318TP9, etc. The calibration of other models of sun photometers can refer to this. 2 Normative References
The following documents are indispensable for the application of this document. For all referenced documents with dates, only the versions with the dates apply to this document. For any undated referenced document, its latest version (including all amendments) applies to this document QX/T270—2015CE318 Sunlight Photometer Observation Procedure 3 Terms and Definitions
The following terms and definitions apply to this document. 3.1
Multi-wavelength sunphotometer
Multi-wavelength sunphotometer is an instrument that measures the radiation signal intensity of the sun and sky at different wavelengths from visible light to near infrared, at different zenith angles, and at different times, and inverts the optical depth of atmospheric aerosols and other characteristics. [QX/T270—2015.Definition 2.3]
Atmospheric mass number
airmass
The ratio of the path of direct light from the sun at any position to that of the direct light from the sun at any position through the weather to the observation point [QX/T270—2015.Definition 2.4]
Integrating sphere
integratingsphere
Ulbrichtsphere is a hollow sphere whose inner surface is as non-selective diffuse reflection layer as possible. Note: Rewrite GB/T26178—2010, definition 2.2.3. 4 Calibration technical indicators
The calibration technical indicators of multi-wavelength sun photometer are as follows: a) The maximum allowable error of aerosol optical thickness at each wavelength between the instrument to be calibrated and the standard instrument should be less than ±0.02. b) The maximum allowable error of sky scattered radiance at each wavelength between the instrument to be calibrated and the standard instrument should be less than ±5%. 1
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5 Principle, composition and wavelength range of observation instruments 5.1 Principle
The photometer automatically tracks the sun and performs measurements such as direct solar radiation, solar equal-angle sky scan, solar main plane scan and polarization channel sky scan. The microphysical and optical radiation parameters such as the optical thickness of aerosols are obtained through algorithm inversion. 5.2 Composition
See Chapter 4 of QX/T2702015.
5.3 Wavelength range
See 5.2 of QX/T270—2015.
6 Calibration conditions
6.1 Overview
6.1.1 It includes two parts: calibration of the direct solar radiation channel and calibration of the sky scattered radiation channel. The direct solar radiation channel calibration should be carried out first, and then the sky diffuse radiation channel calibration should be carried out, and the time interval between the two calibrations should not exceed 7 days. 6.1.2 Direct solar radiation calibration (outdoor calibration): including Langley calibration method (Langley method) and standard instrument relative calibration method (coefficient transfer method), should be carried out in an open-air observation field with a wide field of view. 6.1.3 Sky diffuse radiation channel calibration (indoor calibration): should be carried out in a dark room without the influence of other light sources. 6.1.4 The calibration site should be clean, avoid particulate pollution, and flammable, explosive and highly corrosive materials should not be stored. There should be no strong mechanical vibration and electromagnetic interference around.
6.2 Direct solar radiation channel calibration conditions
6.2.1 During the calibration period (09:00 to 15:00 Beijing time), the sky is clear, cloudless and the atmospheric conditions are stable. 6.2.2 The aerosol optical thickness of the standard instrument at a central wavelength of 440nm should be less than 0.20. 6.2.3 The area near the observation point should be open and there should be no obstacles blocking the observation field of view. 6.2.4 The altitude of the site calibrated using the Langley method should be no less than 2500m. 6.3 Calibration conditions for sky scattered radiation channels
6.3.1 The ambient temperature in the darkroom should be 23℃±1℃, and the relative humidity should be between 20% and 60%. 6.3.2 The power supply in the darkroom should have a good grounding line, and the grounding resistance should be less than 4Ω: it is advisable to be equipped with an uninterruptible power supply with voltage stabilization and filtering functions.
6.4 Calibration equipment, facilities and materials
6.4.1 Standard instrument: a sun photometer with the same functions, parameters and number of channels as the instrument to be calibrated, and meeting the requirements of Chapter 4 a) and b). 6.4.2 Auxiliary calibration equipment: including integrating sphere (spectral range 400nm ~ 2500nm, power not less than 1000W and adjustable, surface non-uniformity less than 1%), integrating sphere control box and bracket and other supporting facilities, computer and calibration software, etc. 6.4.3 Thermometer (instrument): measuring range (-40 ~ 50) ℃, maximum allowable error ± 0.3 ℃. 6.4.4 Humidity meter (instrument): measuring range (10 ~ 100)%, maximum allowable error ± 5%. 6.4.5 Other auxiliary facilities: serial or USB communication cable, dry clean air or dry clean compressed air, deionized water, absorbent cotton, dust-free wiping paper, brush, screwdriver tools, etc.
7 Calibration content and methods
7.1 Preparation before calibration
7.1.1 External inspection
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The overall appearance of the instrument to be calibrated is good, the structure is complete, and all parts are complete. 7.1.2 Internal inspection
QX/T533—2019
7.1.2.1 Check whether the surface of the optical head lighting lens is clean and free of dust, mud, etc. If necessary, use dry and clean compressed air to clean the surface of the lens to remove dust, or use deionized water, absorbent cotton and dust-free wipes to carefully clean the surface of the lens to avoid scratches. 7.1.2.2 Check the transparency of the optical path of the sight. Point the sight toward the light. Use your eyes to observe whether the inside is clean. The optical path should be unobstructed and free of willow catkins, spider webs, insect eggs and other debris. If necessary, use a brush and dry and clean compressed air to clean the inside. 7.1.3 Operation inspection
7.1.3.1 Correctly connect the relevant components of the instrument to be calibrated and the power charger and other components. The instrument should operate normally and the computer should receive data without error display.
7.1.3.2 The integrating sphere, integrating sphere control box and bracket and other supporting facilities in the darkroom, the computer and calibration software can work normally. 7.1.4 Data clearing processing
Before calibrating the instrument, the original observation data should be cleared through the control box. 7.2 Sky scattered radiation calibration
7.2.1 Basic requirements
7.2.1.1 The instrument to be calibrated and the auxiliary calibration equipment required in 6.4.2 should work normally. 7.2.1.2 Turn on the integrating sphere, and the stabilization time of the integrating sphere light source should be no less than 20 minutes. 7.2.2 Installation of the instrument to be calibrated
7.2.2.1 Correctly connect the computer, control box, optical head and other instrument components. 7.2.2.2 Connect the optical head to the sighting tube, and fix the optical head on the bracket system of the integrating sphere. Adjust the bracket so that the sighting tube is aligned with the light exit hole of the integrating sphere.
7.2.3 Calibration of the instrument to be calibrated
7.2.3.1 Check the instrument control box and record the gain value of the instrument to be calibrated before calibration (for CE-318TS9 and CE-318TP9 models, only steps 7.2.3.3 and 7.2.3.6 need to be performed in sequence). 7.2.3.2 Use the instrument control box to adjust the instrument to the manual sky scattered radiation channel observation state, and adjust the gain value so that the signal value obtained by the photometer at each wavelength is between 10000 and 30000. 7.2.3.3 By adjusting the instrument control box, one dark current value observation and no less than 20 sky scattered radiation measurements should be performed at each wavelength, and the calibration data should be saved.
7.2.3.4 Check the calibration data. If the signal value exceeds 30,000, turn off one of the light sources of the integrating sphere in sequence and clear the original calibration data in the instrument control box. After the light source is stable, repeat steps 7.2.3.3 and 7.2.3.4 until the signal value does not exceed 30,000 and the calibration is completed. 3
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7.2.3.5 Adjust the gain value back to the value before the control box calibration and save it. 7.2.3.6 Save the calibration data output as a data file. The file name should contain the optical head number and calibration time information. 7.2.4 Calibration data processing
7.2.4.1 Check the stability of the measurement signal of each wavelength. The relative deviation between the measurement data of the same wavelength should be less than 0.5%. 7.2.4.2 According to the radiation brightness of each wavelength of the integrating sphere, the indoor calibration coefficient is obtained, as shown in formula (1): L()
C() = V()-V().
Wherein:
wavelength, in nanometers (nm);
the calibration coefficient of the sky scattered radiation of the instrument to be calibrated in the input wavelength channel, dimensionless; the radiation brightness of the integrating sphere at the input wavelength, in watts per steradian square meter (W/(sr·m)); the signal value of the instrument to be calibrated in the input wavelength channel, dimensionless; the dark current value of the instrument to be calibrated in the input wavelength channel, dimensionless. 7.3 Direct solar radiation calibration
7.3.1 Basic requirements
7.3.1.1 Under the conditions of 6.2, the Langley method should be used first,...(1)
7.3.1.2 If the calibration site cannot meet the altitude requirements, or the Langley method cannot be used for calibration, the standard instrument relative calibration method should be used for calibration
7.3.1.3 Adjust the gain value of the instrument so that the measurement signal value of each wavelength is between 10000 and 30000. (CE-318TS9 and CE-318TP9 models do not need to perform this step)
7.3.1.4 The instrument to be calibrated should be operated in an outdoor environment for at least 24 hours. 7.3.1.5 When using the relative calibration method of standard instruments, the instrument to be calibrated and the standard instrument should be placed in the same observation field and observed synchronously, and the deviation of the observation time between the two should be less than 10 seconds.
7.3.1.6 The observation data from 10:00 to 14:00 Beijing time and the air mass number between 2 and 6 should be selected as the calibration data. 7.3.2 Calibration method
Principle of Langley calibration method
Use formula (2) to obtain the measured signal value and air mass number curve of the instrument to be calibrated, and calculate the signal value of each wavelength when the air mass number is 0, which is the calibration coefficient of the instrument to be calibrated at this wavelength; InV(a) = In(C(a).R-2)-mt
Where:
wavelength, unit is nanometer (nm);
signal value of the instrument to be calibrated in the input wavelength channel, dimensionless: C().
Calibration coefficient of direct solar radiation of the instrument to be calibrated in the input wavelength channel, dimensionless; R
Correction factor of the distance between the sun and the earth, dimensionless;
Weather mass number, dimensionless;
Total optical thickness of the atmosphere, dimensionless
7.3.2.2 Principle of relative calibration method of standard instrument According to formula (3), the calibration coefficient of each wavelength of the instrument to be calibrated is calculated as follows: 4
. (2)
Where:
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C(in). =C(in), ×
wavelength, in nanometers (nm);
Calibration coefficient of direct solar radiation of the instrument to be calibrated in the input wavelength channel, dimensionless: C().
C(in)——Calibration coefficient of direct solar radiation of the standard instrument in the input wavelength channel. dimensionless; v(a).
The average value of the signal value of the instrument to be calibrated in the input wavelength channel, dimensionless; v(a)
The average value of the signal value of the standard instrument in the input wavelength channel, dimensionless. 7.3.3 Calibration data processing
7.3.3.1 Langley calibration method
The data processing process and method are as follows:
QX/T533—2019
....(3)
Check the relative deviation between the data of each wavelength each time. The ultraviolet wavelength (340nm and 380nm) should be less than 1%, and the other wavelengths should be less than 0.5%. If the requirements cannot be met, the calibration should be carried out again on a selected day. b) Perform the least squares linear fit on the observed values ​​and the atmospheric mass number, and eliminate the discrete values ​​outside the interval of 3 times the standard deviation of the fitting straight line distance obtained by formula (2) (the eliminated data should not exceed 5% of the original data). Obtain at least 10 sets of calibration coefficients for the instrument to be calibrated, and calculate the average value of the calibration coefficients for each wavelength as the final calibration coefficient for the instrument to be calibrated.
7.3.3.2 Relative calibration method for standard instruments
The data processing process and method are as follows:
Remove singular values ​​(values ​​where the observed signal value is 0 or exceeds 30,000). b) Calculate the ratio of the measured signal values ​​of each wavelength between the instrument to be calibrated and the standard instrument. The relative deviation of the ultraviolet wavelength ratio should be less than 2%, and the relative deviation of the ratios of other wavelengths should be less than 1%. If the requirements cannot be met, calibration observations should be carried out on another day. Obtain at least 5 valid data ratios for each wavelength, calculate the average value of the ratios of each wavelength, and substitute them into formula (3) to obtain the calibration coefficient of the instrument to be calibrated.
8 Data archiving
All measurement data shall be named and stored with the optical head number, and at least two copies shall be kept off-site. The integrating sphere observation values ​​and corresponding calibration coefficients measured by the standard instrument and station instrument indoor calibration shall be summarized and organized in a table (see Table A.1 and Table A.2 in Appendix A for the calibration record table template) for subsequent verification.
9 Calibration cycle
Standard instruments and instruments to be calibrated shall be calibrated for the direct solar radiation channel and the sky diffuse radiation channel at least once every 12 months. The integrating sphere shall be calibrated at least once every 24 months. 5
QX/T533—2019
Operator
Standard instrument number
Wavelength/nm
Gain value
Observed value of standard instrument
Calibration coefficient of standard instrument
Observed value of instrument to be calibrated
Calibration coefficient of instrument to be calibrated
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Appendix A
(Informative Appendix)
Calibration record form template for sun photometer
Outdoor calibration record of sun photometer
Calibration date of sun photometer solar direct radiation channel
Optical head number of instrument to be calibrated
Note: Instrument observed value and gain value are dimensionless parameters. Table A.2
Sunlight meter indoor calibration record
Sunlight meter sky diffuse radiation channel calibration operator
Standard instrument number
Select AUREOLE channel
Gain value
Integrating sphere observation value
Calibration coefficient
Select SKY channel
Gain value
Integrating sphere observation value
Calibration coefficient
1020A1
1020@1
1640A2
1640@2
Note: Integrating sphere observation value and gain value are dimensionless parameters Date
Optical head number of instrument to be calibrated
AUREOLE channel refers to the central wavelength of the channel near the solar halo, unit: nm. SKY channel refers to the central wavelength outside the channel near the solar halo, unit: nm. 6
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References
GB/T26178—2010 Measurement method of luminous fluxJJF1002—2010
Rules for compiling national metrological verification procedures
JJF1071—2010 Rules for compiling national metrological calibration specificationsQX/T270—2015
CE318 Observation procedures for sun photometersbzxz.net
China Meteorological Administration. Atmospheric composition observation business specifications (trial) [M. Beijing: Meteorological Press, 2012QX/T533—2019
Holben B. AERONET:A federated instrument network and data archive for aerosol char-16
acterization[J].RemoteSensing of Environment, 1998, 66(1): 1-167
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People's Republic of China
Meteorological Industry Standard
Technical Specification for Calibration of Sunlight Meters
QX/T533-2019
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