Researchers Highlight Need for Caution in Selecting Global Soil Moisture Data

A new study led by Prof. DUAN Weili from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences emphasizes the importance of selecting appropriate datasets for global soil moisture research. The study was published in Science Bulletin on Oct.31.

Soil moisture is a critical factor in regulating the global exchange of water, energy, and carbon.  Accurate measurement is paramount for disaster warning and agricultural planning. However, the proliferation of datasets derived from satellites, land surface models, and reanalysis systems often yields contradictory signals regarding wet and dry trends, particularly in arid regions where water resources are scarce.

In this study, the researchers conducted a comprehensive evaluation of 23 mainstream global soil moisture datasets spanning from 1980 to 2023. They implemented an innovative dual-validation framework, comparing data from 992 stations in the International Soil Moisture Network and a filtered subset of 483 highly representative stations to quantify the impact of spatial heterogeneity.

The findings revealed starkly divergent trends in global soil moisture dynamics. While a slight drying trend dominated the long-term period (1980–2023), a significant number of datasets indicated a shift towards wetting after 2010. In terms of performance, Soil Moisture Active Passive satellite products demonstrated superior capability in capturing temporal dynamics.

Crucially, the study reveals that “spatial representativeness error”—the discrepancy between a single spot measured on the ground and the vast area observed by satellites—can inaccurately mask the true quality of the data.

The researchers found that while the data significantly improved in precision when tested against ground sites that accurately represented the surrounding landscape in tropical regions, the results in arid zones were inconsistent. This underscores the ongoing challenge of accurately monitoring water in drylands.

"Our analysis shows that there is no one-size-fits-all approach to data selection," said Dr. ZHU Ziyang, the study’s first author. "By comparing the strengths and weaknesses of differentdata products, we can significantly enhance the reliability of our research."

This study provides valuable insights and warnings regarding the selection of soil moisture data for hydrological and climatical research in specific regions.

Read the full article: https://doi.org/10.1016/j.scib.2025.10.046

Contact

LONG Huaping

Xinjiang Institute of Ecology and Geography

E-mail: longhp@ms.xjb.ac.cn

Web: http://english.egi.cas.cn