A seamless global 5 km surface soil moisture product from 1982 to 2021

Soil moisture (SM) is an essential climate-sensitive variable that exhibits high spatial and temporal variability. Long-term SM data records (> 30 years) can benefit a range of climate change-related applications. 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 "No Data" values set to -9999.

土壤湿度（Soil Moisture, SM）是至关重要的气候敏感变量，表现出高度的空间与时间变异性。时长超过30年的长期土壤湿度数据记录，可服务于诸多气候变化相关的研究与应用场景。作为全球陆面卫星（Global Land Surface Satellite, GLASS）产品套件的组成部分，本数据集生成了一套1982年至2021年、时间跨度达四十年的全球5公里分辨率逐日土壤湿度产品。该产品（GLASS-AVHRR SM）主要基于注意力机制的深度学习模型，融合GLASS-AVHRR反照率与地表温度（Land Surface Temperature, LST）产品、ERA5-Land再分析土壤湿度产品及辅助数据集生成。GLASS-AVHRR SM产品具备长期覆盖范围广、时空完整性佳、精度可靠且一致性优异的优势。GLASS-AVHRR SM产品的数据值代表最上层0至5厘米土层的体积含水量。数据文件采用地理投影坐标系存储，以GeoTIFF格式提供，无数据（No Data）值设为-9999。