GB/T 40033-2021
Validation of land surface evapotranspiration remote sensing products (English Version)
- Standard No.
- GB/T 40033-2021
- Language
- Chinese, Available in English version
- Release Date
- 2021
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 40033-2021
- Scope
- This standard specifies the basic requirements, inspection methods and inspection reports for the authenticity inspection of surface evapotranspiration remote sensing products. This standard is applicable to the authenticity inspection of daily/monthly/yearly global scale and regional scale surface evapotranspiration remote sensing products.
- Introduction
Analysis of the core content of the standard
This standard systematically specifies the technical requirements for the entire process of authenticity verification of surface evapotranspiration remote sensing products, focusing on solving the problem of incomparable current verification results. Its technical framework includes the standardized application of ground observation equipment such as eddy correlator and scintillometer, as well as innovative verification methods such as the triple test method and the triangular hat method.
Comparison of test methods
Dimension Direct test method Cross-test method Spatial-temporal trend analysis method Applicable conditions With ground observation data ≥3 kinds of remote sensing products With influencing factor data Spatial scale Pixel/regional scale Spatial registration required Spatial-temporal consistency required Accuracy indicators RMSE, Bias Triple/Triangle Hat Method Trend Fit
Key Implementation Points
Instrument Selection Specifications
Appendix A of the standard clearly states: Eddy Correlator is suitable for medium and high resolution product verification (tens to hundreds of meters in the source area), and Dual Band Scintillometer is for 1-5km low resolution products. During installation, it is necessary to ensure that the ultrasonic anemometer has a balanced horizontal bubble and the scintillator light path should be perpendicular to the main wind direction.
Data Quality Control
Data quality is graded through turbulence stationarity test (eddy correlator) and Monin-Obukhov theory verification (scintillator), and only high/medium quality data can be used for verification. A typical example is that the Qinghai-Tibet Plateau stations need to additionally consider the data correction of the ice and snow sublimation process.
Background of technological evolution
This standard makes up for the problems of scale mismatch (such as flux source area and pixel deviation) and inconsistent methods in traditional verification. By introducing relative true value calculation (Appendix B) and error covariance matrix (Appendix C), the verification results of different institutions are comparable. Compared with the previous draft, the 2021 version adds a spatiotemporal trend analysis method to adapt to the verification scenarios where there is a lack of ground data in large areas.
Industry application suggestions
- Water conservancy department: Establish an operational verification system for watershed evapotranspiration products in combination with this standard
- Ecological monitoring: Give priority to homogeneous surface sites for long-term observation data accumulation
- Satellite missions: Consider the requirements of this standard for resolution matching during the sensor design stage
GB/T 40033-2021 Referenced Document
- GB/T 36296-2018 Guide for the validation of remote sensing products
- GB/T 39468-2020 General methods for the validation of terrestrial quantitative remote sensing products
GB/T 40033-2021 history
- 2021 GB/T 40033-2021 Validation of land surface evapotranspiration remote sensing products