GB/T 41281-2022 in English

GB/T41281-2022 is my country's first national standard specifically for the authenticity inspection of photosynthetically active radiation (PAR) remote sensing products, which was formulated by the Institute of Space Information Innovation of the Chinese Academy of Sciences. The standard system regulates the inspection methods of various observation equipment, from global pyranometers to photometers.

1. Radiation data conversion

The standard defines the conversion formulas of the two measurement systems:
Photon → Energy: UPAR=4.55×QPAR
Total radiation → PAR: QPAR=ηQ×Q (ηQ is 0.3-0.5)

2. Spatial representativeness evaluation

The radiation correlation intensity (CS) indicator is used, and the site CS value must be ≥0.8 to be used as a valid reference point to ensure the representativeness of data within a range of 50km×50km.

3. Time consistency processing

For products with different time resolutions:
- Instantaneous products: take the average of the 30 minutes before and after
- Daily accumulation: integrate and calculate the 24h value
- Monthly/yearly accumulation: accumulate daily

Equipment selection recommendations

Give priority to hemispherical radiometers that comply with GB/T33867-2017 standard. The annual stability should be controlled within 5%.

Inspection process optimization

It is recommended to adopt the "three-stage verification method":
1. Single-station equipment comparison
2. Regional network verification
3. Full product cross-verification

Typical application cases

In the Heihe comprehensive test, the application of PAR products verified by this standard in farmland ecosystems showed that: the inversion accuracy was improved by 12%, and the crop growth model fit reached 0.89.