Qi et al. (2026) Soil-atmosphere compound extreme droughts have become more frequent and severe in China over the past four decades

Identification

• Journal: Weather and Climate Extremes
• Year: 2026
• Date: 2026-07-01
• Authors: Guizeng Qi, Jinxi Song, Dunxian She, Shouzhi Chen, Yufeng Gong, Hongying Bai, Jun Xia, Yongshuo H. Fu
• DOI: 10.1016/j.wace.2026.100932

Research Groups

• College of Water Sciences, Beijing Normal University
• Xi'an Key Laboratory of Environmental Simulation and Ecological Health in the Yellow River Basin, Northwest University
• State Key Laboratory of Water Resources Engineering and Management, Wuhan University
• Hubei Key Laboratory of Water System Science for Sponge City Construction, Wuhan University

Short Summary

This study reveals the spatiotemporal evolution patterns of compound drought events in China from 1980 to 2023. The results show a significant negative correlation between soil moisture (SM) and vapor pressure deficit (VPD), with their joint distribution exhibiting a bimodal pattern. The frequency, duration, and exposed area of compound extreme droughts have all increased significantly.

Objective

• Investigate the spatiotemporal evolution characteristics and driving factors of soil-atmosphere compound droughts in China.
• Characterize the temporal changes in the annual occurrence window of compound extreme droughts.

Study Configuration

• Spatial Scale: Continental scale, covering the entire territory of China.
• Temporal Scale: Daily-scale data from 1980 to 2023.

Methodology and Data

• Models used: Copula models for describing the dependence between SM and VPD; Structural Equation Modeling (SEM) for analyzing the driving factors of compound extreme drought severity.
• Data sources: ERA5-Land soil moisture and meteorological variables, leaf area index (LAI), gross primary productivity (GPP), Digital Elevation Model (DEM).

Main Results

• The joint occurrence probability of extremely low SM and extremely high VPD was substantially higher than the expected probability under the assumption of independence.
• The start time of compound extreme drought events in China has advanced at a rate of 0.19 day⋅yr−1, while the end time has been delayed at a rate of 0.40 day⋅yr−1.
• The frequency (0.25 events⋅yr−1), duration (0.16 day⋅yr−1), and affected area (0.53%⋅yr−1) of compound extreme droughts increased significantly.

Contributions

• This study provides a comprehensive understanding of the spatiotemporal evolution patterns of compound drought events in China.
• The results highlight the importance of considering the coupling mechanism between SM and VPD for predicting compound drought occurrence.

Funding

• National Natural Science Foundation of China (Grant No. 42175053)
• Ministry of Education of China (Grant No. 21YJC910001)
• Hubei Provincial Department of Education (Grant No. B2020001)

Citation

@article{Qi2026Soilatmosphere,
  author = {Qi, Guizeng and Song, Jinxi and She, Dunxian and Chen, Shouzhi and Gong, Yufeng and Bai, Hongying and Xia, Jun and Fu, Yongshuo H.},
  title = {Soil-atmosphere compound extreme droughts have become more frequent and severe in China over the past four decades},
  journal = {Weather and Climate Extremes},
  year = {2026},
  doi = {10.1016/j.wace.2026.100932},
  url = {https://doi.org/10.1016/j.wace.2026.100932}
}