HONG et al. (2026) Characteristics and influencing factors of soil moisture memory across mainland China

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-03-10
• Authors: Xu HONG, Shaofeng Jia, Wenbin Zhu
• DOI: 10.1016/j.jhydrol.2026.135281

Research Groups

• Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
• University of Chinese Academy of Sciences, Beijing, China

Short Summary

This study utilized 2,218 daily in situ soil moisture observations across mainland China to characterize the spatial patterns and influencing factors of soil moisture memory (SMM) using an exponential drydown model, highlighting its heterogeneity and discrepancies with satellite/reanalysis products.

Objective

• To provide the first comprehensive assessment of soil moisture memory (SMM) over mainland China using extensive in situ observations, investigating its spatial and depth-dependent characteristics and key controlling factors.

Study Configuration

• Spatial Scale: Mainland China
• Temporal Scale: Daily observations

Methodology and Data

• Models used: Exponential drydown model
• Data sources: 2,218 daily in situ soil moisture observations across mainland China; Independent site-specific wilting point observations; Multiple satellite and reanalysis soil moisture products

Main Results

• The exponential drydown model reliably captures soil moisture status, with fitted estimated lower bound of soil moisture (̂θw) values showing good agreement with independent wilting point observations (adjusted R² = 0.58).
• All fitted parameters (e-folding time scale τ, ̂θw, and magnitude of the drydown event Δθ) exhibit pronounced spatial heterogeneity across mainland China, particularly between North and South China and between coastal and inland areas.
• As soil depth increases, Δθ decreases, ̂θw increases, and τ shows a non-monotonic pattern (first increases and then decreases).
• ̂θw is primarily governed by soil texture, especially clay content.
• τ is more sensitive to meteorological factors, particularly evapotranspiration.
• Most satellite and reanalysis soil moisture products systematically underestimate τ and show spatially inconsistent patterns compared to in situ observations.

Contributions

• Provides the first comprehensive assessment of soil moisture memory (SMM) over mainland China based on a large amount of in situ soil moisture observations.
• Reveals the spatial and depth-dependent characteristics of SMM and its key controlling factors.
• Offers new insights into the mechanisms governing SMM and highlights limitations in current land surface models regarding soil drying processes.
• Has implications for improving drought diagnosis and land–atmosphere interaction modeling.

Funding

• Not specified in the provided text.

Citation

@article{HONG2026Characteristics,
  author = {HONG, Xu and Jia, Shaofeng and Zhu, Wenbin},
  title = {Characteristics and influencing factors of soil moisture memory across mainland China},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135281},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135281}
}