Feng et al. (2025) Spatiotemporal evolution and driving mechanisms of compound dry and hot events in the Yellow River Basin under climate warming

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-11-01
• Authors: Xinyuan Feng, Yanghua Wang, Yi‐Chi Wang, Jianshun Wang, Xiaoli Liu, Fei Liu
• DOI: 10.1007/s00704-025-05870-9

Research Groups

• Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province, Key Open Laboratory of Arid Change and Disaster Reduction of CMA, Lanzhou, China
• Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, Gansu, China
• Nanjing University of Information Science and Technology, Nanjing, 210044, China

Short Summary

This study investigates the spatiotemporal evolution and driving mechanisms of compound dry and hot events (CDHEs) in the Yellow River Basin from 1960 to 2023, revealing a significant increase in extreme CDHEs since a 1996 climate regime shift, primarily driven by positive land-atmosphere feedbacks with spatially varying mechanisms.

Objective

• To examine the multi-scale variations in CDHEs frequency, intensity, and spatial distribution, along with their response to climate warming.
• To quantify the regulatory roles of key meteorological factors and identify dominant formation mechanisms across different climatic subregions.

Study Configuration

• Spatial Scale: Yellow River Basin, China, with an approximate area of 750,000 square kilometers, divided into six climatic subregions (A–F).
• Temporal Scale: June to October annually, over the period 1960–2023.

Methodology and Data

• Models used:
  • Compound Dry and Hot Event (CDHE) index (developed in study)
  • Standardized Precipitation Index (SPI)
  • Standardized Temperature Index (STI)
  • Mann–Kendall test (for trend-break analysis)
  • Correlation analysis
  • Random Forest Regression
  • Principal Component Analysis (PCA)
  • SMOTE (Synthetic Minority Oversampling Technique) algorithm
• Data sources:
  • Daily precipitation and temperature data (1960–2023) from meteorological station observations.
  • Reanalysis data (e.g., ERA5-Land for Surface sensible heat flux (SSHF), Skin reservoir content (SRC), Potential evaporation (PET), Volumetric soil water layer 1 (VSWL1)).
  • Remote sensing products (e.g., Normalized Difference Vegetation Index (NDVI)).

Main Results

• High-frequency CDHEs zones exhibit significant spatial clustering, with the central Loess Plateau and the Guanzhong Plain identified as hotspots, particularly for high-intensity events (L4 and L5). The frequency of L4–L5 CDHEs significantly increased at rates of 3.03% and 4.72% per decade, respectively.
• A climatic mutation point was identified in 1996 by the Mann–Kendall test. Following this shift (1997–2023), the frequency of extreme CDHEs increased from 4.67% to 11.59%, and their spatial coverage expanded from 20% to 43%, indicating a substantial intensification and expansion due to climate warming.
• CDHEs are primarily driven by positive land–atmosphere feedbacks. The dominant driving mechanisms show a spatial evolution from energy-dominated in the upper reaches, to hydrothermal-dominated in the middle reaches, and finally to moisture-dominated in the lower basin, reflecting spatial heterogeneity in hydrothermal conditions.

Contributions

This study addresses the underexplored long-term evolution, spatial heterogeneity, and formation mechanisms of compound dry and hot events (CDHEs) in the Yellow River Basin, contrasting with previous research focused primarily on the Yangtze River Basin. It provides a systematic investigation of CDHEs' spatiotemporal evolution and regional differences in their formation mechanisms using long-term multi-source data, identifies a critical climate regime shift in 1996, and details the spatially varying land-atmosphere feedback mechanisms across the basin's diverse climatic zones.

Funding

• The Science and Technology Program of Gansu Province [grant number 25JRRA1113]
• The National Natural Science Foundation of China (Key Project) [grant number 42230611]
• The Innovation and Development Project of The China Meteorological Administration [grant number CXFZ20241037]
• The Meteorological Soft Science Research Project of the China Meteorological Administration [grant number 2020ZDIANXM22]
• The Third Cohort of the Longyuan Young Elites Program

Citation

@article{Feng2025Spatiotemporal,
  author = {Feng, Xinyuan and Wang, Yanghua and Wang, Yi‐Chi and Wang, Jianshun and Liu, Xiaoli and Liu, Fei},
  title = {Spatiotemporal evolution and driving mechanisms of compound dry and hot events in the Yellow River Basin under climate warming},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05870-9},
  url = {https://doi.org/10.1007/s00704-025-05870-9}
}