A four-decade global 5-km daily SM product has been generated from 1982 to 2021, as part of the Global Land Surface Satellite (GLASS) products suite. This product (GLASS-AVHRR SM) was derived mainly from the GLASS-AVHRR albedo and LST products, the ERA5-Land reanalysis SM product, and auxiliary datasets, using an attention-based deep learning model. The GLASS-AVHRR SM product has the advantages of long-term coverage, spatial and temporal integrity, reliable accuracy and consistency.

The data values in the GLASS-AVHRR SM product represent the volumetric water content of the uppermost soil layer (0–5 cm). The files are stored in geographic projection and provided in Geo Tiff format, with areas of permanent snow and ice and water bodies masked. A scale factor of 1000 is applied, and 'No Data' values are set to -9999.