Validation of land surface evapotranspiration remote sensing products

GB/T 40033-2021.Validation of land surface evapotranspiration remote sensing products.
1 Scope
GB/T 40033 specifies the basic requirements, test methods and test reports for the authenticity test of land surface evapotranspiration remote sensing products.
GB/T 40033 is applicable to the authenticity test of land surface evapotranspiration remote sensing products at daily/monthly/annual global and regional scales.
2 Normative references
The following documents are indispensable for the application of this document. For all dated references, only the dated versions apply to this document. For all undated references, the latest versions (including all revised versions) apply to this document.
GB/T 36296-2018 Guidelines for authenticity verification of remote sensing products
GB/T 39468-2020 General method for authenticity verification of land quantitative remote sensing products
3 Terms and definitions
GB/T 36296-2018 and GB/T 39468-2020 and the following terms and definitions apply to this document.
3.1
land surface evapotranspiration
The process by which liquid water or solid water enters the atmosphere through the interfaces of vegetation, soil, water bodies, ice and snow on the land surface and turns into water vapor.
Note 1: It includes vegetation evaporation, evaporation of precipitation stored in soil, water bodies and vegetation canopy, and sublimation of ice and snow.
Note 2: The unit is millimeter (mm).
3.2
Flux source area
The upwind area that makes the main contribution to the flux observation.
Note: It can be obtained by integrating the instrument observation value and the transmission rainfall number of the spatial distribution of surface sources/sinks in the near-surface layer over a specific area.
4 Basic requirements
The authenticity test of surface evapotranspiration remote sensing products shall comply with the provisions of Chapter 7 of GB/T 36296-2018 and meet the following requirements:
a) The reference object shall be in the same area at the same time as the surface evapotranspiration remote sensing product to be tested;
b) The reference object shall cover the main surface types in the test area and have high, medium and low surface evapotranspiration values;
c) The reference object shall first be the ground-based observed surface evapotranspiration data, or the tested or multiple tested surface evapotranspiration remote sensing products (or model products, reanalysis data, etc.) with the same projection method and consistent temporal and spatial resolution as the surface evapotranspiration remote sensing product to be tested, or the tested surface evapotranspiration influencing factor data.
This standard specifies the basic requirements, test methods and test reports for the authenticity test of surface evapotranspiration remote sensing products. This standard is applicable to the authenticity verification of daily/monthly/annual global and regional scale surface evapotranspiration remote sensing products.