other information
drafter:Jin Rui, Kang Jian, Ma Chunfeng, Zhu Zhongli, Ran Youhua, Zhao Tianjie, Wu Shengli, Li Xin, Liu Zhaoyan
Drafting unit:Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Beijing Normal University, Institute of Space Information Innovation, Chinese Academy of Sciences, National Satellite Meteorological Center, Institute of Tibetan Plate
Focal point unit:National Remote Sensing Technology Standardization Technical Committee (SAC/TC 327)
Proposing unit:Chinese Academy of Sciences
Publishing department:State Administration for Market Regulation National Standardization Administration
Some standard content:
ICS07.040
National Standard of the People's Republic of China
GB/T40039—2021
Validation of soil moisture remote sensing products Issued on April 30, 2021
State Administration for Market Regulation
National Administration of Standardization
Implementation on November 1, 2021
GB/T40039—2021
Normative reference documents
Terms and definitions
Basic requirements
Test methods
Selection of test methods
White-link test method
Selection of validation area
Sample selection
Synchronous measurement of ground data
Determination of relative true value at pixel scale
Accuracy evaluation| |tt||Uncertainty analysis
Indirect test method
6 Test report
Cover information
Main text information
Overview of remote sensing products of soil moisture to be tested
Description of reference objects
Test methods and processes
Authenticity test conclusion
Additional information
6.3 Brief table of test report information
Appendix A (Normative Appendix) 10 References to soil moisture measurement methods·
Ring knife method
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This standard was drafted according to the rules given in GB/T1.12009. The standard was proposed by the Chinese Academy of Sciences.
This standard is issued by the National Remote Sensing Technology Standardization Technical Committee (SAC/TC327) and is under the jurisdiction of GB/T40039—2021
The drafting units of this standard are: Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Beijing Normal University, Institute of Space Information Innovation, Chinese Academy of Sciences, National Satellite Meteorological Center, Institute of Tibetan Plateau Research, Chinese Academy of Sciences. The drafters of this standard card are: Jin Rui, Kang Jian, Ma Chunfeng, Zhu Zhongli, Zai Youhua, Zhao Tianjie, Wu Shengli, Li Xin, Liu Zhaoyan. rrKaeerkAca-
GB/T 40039—2021
Upper soil moisture is one of the core variables of the global climate system and plays an important role in the energy and water balance of the surface and atmosphere. Upper soil moisture directly determines the proportion of precipitation converted into evapotranspiration, infiltration and runoff, and is a basic variable in the formation, transformation and consumption of terrestrial water resources. In addition, soil moisture is also the basic material condition for vegetation growth, affecting the photosynthesis rate of vegetation and the respiration of soil microorganisms: soil moisture remote sensing products have become an indispensable key parameter in the fields of climate, meteorology, hydrology, ecology and agriculture. The authenticity test of soil moisture remote sensing products is a basic method to independently evaluate the accuracy and uncertainty of soil moisture remote sensing products. At present, there is still a lack of standards for the objective evaluation and quantitative test of the quality of soil moisture remote sensing products. Therefore, it is necessary to form a set of reasonable, standardized and feasible soil moisture remote sensing product authenticity test standards to ensure the quality and consistency of soil moisture remote sensing products in related research and applications.
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1Scope
Authenticity test of soil moisture remote sensing products, GB/T40039—2021
This standard specifies the basic requirements, test methods and test reports for the authenticity test of soil moisture remote sensing products. This standard is applicable to the authenticity test of soil moisture remote sensing products at global and regional scales. Normative references
The following documents are essential for the application of this document: For all references with dates, only the versions with dates apply to this document. For all references without dates, the latest versions (including all amendments) apply to this document. GB/T28418-2012 Basic technical conditions for soil moisture (abstract) monitoring instruments GB/T36296-2018 Guidelines for authenticity inspection of remote sensing products G3/T39468-2020 General method for authenticity inspection of land quantitative remote sensing products 3 Terms and definitions
The terms and definitions defined in GB/T28418-2012, (B/T36296-2018, G3/T39468-2020) and the following terms and definitions apply to this document.
Soil moisture
soilmoisture
Water adsorbed on soil particles and existing in soil pores: Note: mainly liquid water, a small amount is solid ice frozen in cold seasons and gaseous water in the form of water vapor, 3.2
Volume soil moisture
Volumetric soil moisture
The volume of liquid water contained in a unit volume of soil. Note: The unit is cubic centimeters per cubic meter (cm*/cm2) 3.3
Gravimetric soil moisture
Gravimetric soil moisture
Gravimetric soil moisture
The ratio of the mass of liquid water retained in the soil to the mass of dry soil. Note: The unit is grams per gram (g/).
Bulk density
Bulk density of soil
The mass of soil in the original state per unit volume. Note: The unit is grams per cubic centimeter (g/cm). 4 Basic requirements
The authenticity inspection of soil moisture remote sensing products shall comply with the provisions of Chapter 7 of (G13/T36296-2018) and meet the following requirements: -rrKaeerkca-
GB/T 40039—2021
The reference object shall be the soil moisture data of the same region in the same or adjacent period (no more than 24 hours) as the soil moisture remote sensing product to be tested.
b) The reference object and the soil moisture remote sensing product to be tested shall be the same soil volume moisture content; if it is soil weight moisture content, it shall be converted to soil volume moisture content through soil bulk density.
c) The reference object shall cover the main lichen types in the verification area (except water bodies, ice and snow, towns and construction land), and each main surface type shall include three soil moisture conditions of high, medium and low. d) The root mean square error of the reference object shall be less than 0.01 cm/cm, 5 Verification method
Verification method selection
The authenticity verification methods of soil moisture remote sensing products include direct verification method and indirect verification method: Select the verification method according to the availability of the reference object:
a) Soil moisture and ground synchronous measurement data should be selected as the reference object, and the direct verification method should be adopted: b) When there is no synchronous measurement data of soil moisture and ground, the verified soil moisture products can be used as the reference object, and the indirect verification method should be adopted.
5.2 Direct verification method
5.2.1 Overview||tt| |The operation process of the joint inspection method should comply with the provisions of 8.1 of GB/T362962018. The main operation process is shown in Figure 1. Verification area selection
To be inspected·Moisture remote sensing products
5.2.2 Verification area selection
Spatial matching
Accuracy evaluation
Uncertainty analysis
Direct inspection method operation process
Group selection
Ground data synchronous measurement
Pixel scale relative true value determination
When the spatial resolution of the soil moisture remote sensing product to be inspected is coarser than or equal to When the spatial resolution of the soil moisture remote sensing product to be tested is better than 5km, at least the surface area corresponding to 1 pixel of the soil moisture remote sensing product to be tested should be selected as the verification area: when the spatial resolution of the soil moisture remote sensing product to be tested is better than 5km, at least the surface area corresponding to 2×2 pixels of the soil moisture remote sensing product to be tested should be selected as the verification area. The verification area should be spatially matched with the soil moisture remote sensing product to be tested, and the prior information related to the verification area and soil moisture should be collected. According to the provisions of 4.2 in (G13/T39168-2020, the soil moisture is judged in -rKaeerkca-
GB/T40 039—2021
Spatial differences: Prior information can be soil moisture, surface thermal inertia, surface temperature, vegetation index, soil evaporation efficiency, etc. The spatial resolution of the prior information should not be lower than the spatial resolution of the ten soil moisture remote sensing products to be tested. 5.2.3 Sample selection
According to the results of the spatial heterogeneity analysis of soil moisture in the verification area. According to 4.3.1 of GB/T39468-2020, select an appropriate spatial sampling model to determine the sample location: the sample size of each pixel in the verification area is not less than 4, and there is at least 1 sample for each major surface type. 5.2.4 Synchronous measurement of ground data
According to 5.2.3. Determine the sample position and carry out synchronous ground measurement of soil moisture. The specific requirements are as follows: a) It should be measured in retrograde mode in the original state. b) If the soil moisture remote sensing product to be tested is surface soil moisture, the measurement depth should be between 0cm and 10cm. If the soil moisture remote sensing product to be tested is root zone soil moisture, the measurement depth should be determined according to the vegetation root system. c) It is preferred to use dynamic monitoring instruments to measure soil moisture. The basic technical conditions of the soil moisture monitoring instrument shall comply with the provisions of (G3/T281182012, and the measurement value range shall be 0cm/cm~0.6cm/cm, the measurement resolution shall not be lower than 0.001cm/cm, the measurement error of the soil moisture monitoring instrument shall be calibrated by the drying method, the absolute error shall not be higher than 0.03cm/cm, and the standard deviation of the repeatability of the measurement result shall not be greater than 0.02cm/cm. The soil moisture measurement of the soil moisture monitoring instrument includes two methods: fixed-position continuous measurement and mobile measurement. The fixed-position continuous measurement can use the observation value closest to the acquisition time of the soil moisture remote sensing product to be tested as the sample measurement value. The mobile measurement should continuously measure at least two soil moisture at the same sample position and calculate the average value as the sample measurement value. If no dynamic monitoring instrument is equipped, the ring knife method is used: collect at least two original samples at the same sample location to measure the soil moisture e)
and then calculate the mean value as the sample measurement value. The measurement method is shown in Appendix A. 5.2.5 Determination of relative true value of pixel scale
According to the spatial resolution of the soil moisture remote sensing product to be tested, the spatial heterogeneity of soil moisture in the verification area and the spatial representativeness of the sample, select the corresponding situation and method in accordance with 4.4.1 of GB/T39468-2020, and convert the sample measurement value scale into a relative true value consistent with the pixel resolution and space of the soil moisture remote sensing product to be tested. 5.2.6 Accuracy evaluation
According to the accuracy evaluation indicators specified in 6.1 of GB/T36296-2018, such as root mean square error, correlation coefficient, average error, average absolute error, relative error, average relative error, and average absolute relative error, the accuracy of the soil moisture remote sensing product to be tested is quantitatively expressed. For the calculation method of accuracy evaluation index, please refer to Appendix A of GB/T36296-2018. 5.2.7 Uncertainty analysis
According to the uncertainty evaluation indexes such as standard deviation, variance, covariance, standard uncertainty, etc. specified in 6.2 of GB/T36296-2018, the uncertainty of the soil moisture remote sensing product to be tested is quantitatively expressed. For the calculation method of uncertainty evaluation index, please refer to Appendix B of GB/T36296-2018.
5.3 Indirect verification method
The spatial resolution of the tested soil moisture product should not be lower than the spatial resolution of the soil moisture remote sensing product to be tested. It is advisable to adopt the cross-verification method specified in 8.2.1 of GB/T3629-2018. The specific operation process is shown in Figure 2. The main steps are as follows: a) Spatial consistency check: When the pixel resolution of the soil moisture remote sensing product to be checked is different from that of the tested soil moisture product or the spatial resolution is not consistent, the tested soil moisture product is scaled using the spatial averaging method; b) Sample selection: When the number of pixels of the soil moisture remote sensing product to be checked is less than or equal to 10,000, all pixels can be directly compared and verified: When the number of pixels is greater than 10,000, a spatial sampling method that meets statistical significance is used for sample selection. For sample selection method and sample size determination, please refer to Appendix G3/139468-2020 [3. Accuracy evaluation: When the time span of the soil moisture remote sensing product to be tested is less than 15 days, analyze the consistency of the spatial distribution between the soil moisture remote sensing product to be tested and the tested soil moisture products; when the time span of the soil moisture remote sensing product to be tested is greater than or equal to 15 days, the consistency of the time change trend of the soil moisture remote sensing product to be tested and the tested soil moisture products should also be tested. The accuracy of the soil moisture remote sensing product to be tested is quantitatively expressed according to the root mean square error, correlation coefficient, average error, average absolute error, relative error, average relative error, average absolute relative error and other accuracy evaluation indicators specified in 6.1 of GB/T36296-2018. For the calculation method of accuracy evaluation indicators, please refer to Appendix A of GB/T36296-2018. Uncertainty analysis: The uncertainty of the soil moisture remote sensing product to be tested is quantitatively expressed according to the uncertainty evaluation indicators such as standard deviation, variance, covariance, standard uncertainty and other uncertainty evaluation indicators specified in 6.2 of GB/T36296-2018. For the calculation method of uncertainty evaluation index, please refer to Appendix B of GB/T36296-2018.
Soil moisture remote sensing product to be inspected
6 Inspection report
Cover information
The cover of the inspection report should include the following information: Inspection report number;
Inspection report name;
Inspection person in charge:
Inspection checker;
Inspection issuer;
Inspection unit;
Inspection unit;
Inspection time,
Spatial consistency||tt| |Sample selection
Accuracy evaluation
Uncertainty analysis
Inspected soil moisture products
Spatial scale conversionwww.bzxz.net
Operation process of indirect verification method
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Main information
6.2.1 Overview of soil moisture remote sensing products to be tested GB/T40039—2021
Describe the data source, spatiotemporal coverage, spatiotemporal resolution, projection method, data unit, data format, and product algorithm of the soil moisture remote sensing products to be tested.
6.2.2 Description of reference object
Describe the measuring instrument, measurement method, measurement time, measurement location, data unit, data format, data processing flow, octave conversion method and data quality of the reference object. 6.2.3 Verification method and process
Describe the adopted verification method and verification process, which includes: a) Verification method; b) Verification process; c) Evaluation index.
6.2.4 Authenticity verification conclusion
Describe the authenticity verification result. It is recommended to include: a) Overall evaluation: Describe the overall accuracy, temporal continuity, spatial continuity, etc. of the soil moisture remote sensing product to be tested; b) Accuracy evaluation: Quantitatively give the statistical results of each accuracy evaluation index, describe the accuracy of the soil moisture remote sensing product to be tested, the accuracy under different surface types and different soil moisture conditions, and the degree of consistency with the spatial distribution and temporal changes of the reference object.
) Uncertainty analysis: describe the observation error, representative error, octave conversion error and uncertainty of the soil moisture remote sensing product to be tested.
d) Propose improvement suggestions for the soil moisture remote sensing product to be tested 6.2.5 Additional information
Explain and describe the problems in the authenticity test process of the ten soil moisture remote sensing products. 6.3 Test report information summary
For the preparation of the soil moisture remote sensing product test report information summary, please refer to G3/T36296-2018 Appendix 1). 5
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GB/T 40039—2021
Appendix A
(Normative Appendix)
Soil moisture measurement method
The specific method for measuring soil moisture by ring knife method is as follows: Ring knife method
Select ring knives of different specifications according to the gravel content in the soil: when the gravel content is less than 10%, use a ring knife with a volume of 100cm200cm
; when the gravel content is greater than or equal to 10%, use a ring knife with a volume of 500cm. Prepare an empty aluminum box with a volume of more than 20%, wash and dry it, weigh it, and record the weight of the aluminum box. b)
Use a circular knife to obtain the original state. When taking samples, apply even force to avoid compacting the sample. All soil samples obtained by the circular knife are placed in an aluminum box and sealed with a lid. Bring it back to the laboratory for analysis as soon as possible: d)
Use an electronic balance with an accuracy of not less than 0.018 for weighing in the experiment, and record the weight W of the wet soil plus the aluminum box. Remove the lid of the aluminum box and put it in the oven, and dry it at 105°C to constant weight (the difference between the two weighings should not be less than 0.02g): Take out the aluminum box from the oven. Cover the box, cool it to room temperature, and immediately weigh it with an electronic balance, and record the weight of the aluminum box. When measuring samples with high organic matter or root content, the oven temperature can be appropriately lowered to 85°C~90°C to record the measurement data (see Table A.1). Calculate the soil moisture according to formula (A.1) to formula (A.3): g)
W±-W+×100%
Mw-WT-W
M-MwXph
Where:
+soil weight moisture content.The unit is gram per gram (g/g); the weight of the wet lead box is in grams (g); the weight of the aluminum box is in grams (g); the weight of the aluminum box is in grams (g); the bulk density of the soil is in grams per cubic meter (g/cm\); the ring knife volume is in cubic meter (cm); the soil volume water content is in cubic centimeters per cubic centimeter (cm/cm\) Table A.1 Ring knife method soil moisture data recording table (A.1)| |tt||.(A.2)
Aluminum box numberBox weight/gBox/wet soil/gBox ten soil/dry soil weight/gBulk density/(g/cm2)Weight moisture content/(g/g)Volume moisture content/(cm2/cm)Place of collection:
Recording time:
Person of collection:
Recording person:
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Weighing person:
[1_GB/T1526 1989
Documentation symbols and conventions for source drawings
L2_GB/T3358.1—2009
Information processing
References
GB/T40039—2021
Data flow chart, program flow chart, system flow chart, program network diagram and system information Statistics vocabulary and symbols Part 1: - Statistical terms and terms used in probability [3 (G13/T3358.2—2009
Statistical vocabulary and symbols Part 2: Applied statistics [[4_JJF1059.12012 Evaluation and expression of uncertainty in measurement L5_
QX/T752007
Determination of soil moisture in microwave ovens
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GB/T 40039-2021
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National Standard
Authenticity inspection of soil moisture remote sensing products
GB/T 4G0392021
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First edition in April 2021
Book number: 135066·167032
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