Zhu et al. (2025) Drought identification using standardized evaporative fraction: Perspective from surface energy partitioning

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-11-17
• Authors: Hongyu Zhu, Ren Wang, Lijuan Chen, Haishan Chen
• DOI: 10.1016/j.jhydrol.2025.134609

Research Groups

• State Key Laboratory for Climate System Predictions and Risk Management/Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China
• School of Atmospheric Science, Nanjing University of Information Science and Technology, Nanjing 210044, China
• Nanjing University of Science and Technology Zijin College, Nanjing 210023, China

Short Summary

This study introduces the Standardized Evaporative Fraction (SEF) as a new drought index, derived from surface energy partitioning, to better incorporate land-atmosphere interactions in drought identification. The SEF is shown to be effective globally from 1960–2022, demonstrating good consistency with existing indices and revealing increasing drought trends in several global hotspots.

Objective

• To propose and evaluate a new drought index, the Standardized Evaporative Fraction (SEF), constructed from the perspective of surface energy partitioning, to account for the impact of land-atmosphere interactions on drought intensity and evolution, and to identify global drought characteristics.

Study Configuration

• Spatial Scale: Global scale
• Temporal Scale: 1960–2022 (63 years)

Methodology and Data

• Models used: Standardized Evaporative Fraction (SEF) (newly proposed index), Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Soil Moisture Index (SSMI).
• Data sources: FLUXNET observations (for correlation analysis), global gridded data (implied for global analysis).

Main Results

• The SEF is effective for identifying drought events, particularly when surface solar radiation is unconstrained.
• Analysis based on FLUXNET observations indicates a significant correlation (p < 0.05) between SEF and the SPEI, demonstrating good consistency.
• The SEF identifies hot spots of increasing droughts globally.
• Drought frequency, duration, and intensity have increased in western North America, central South America, central Africa, southern Europe, and central and north-east Asia over the past 63 years.

Contributions

• Proposes a novel drought index (SEF) that incorporates surface energy partitioning and land-atmosphere coupling effects, addressing a limitation of traditional precipitation/temperature-based indices.
• Provides added value in capturing land-atmosphere interactions on drought, especially in regions with strong coupling.
• Offers a new perspective for global drought identification and trend analysis.

Funding

• [Not specified in the provided text.]

Citation

@article{Zhu2025Drought,
  author = {Zhu, Hongyu and Wang, Ren and Chen, Lijuan and Chen, Haishan},
  title = {Drought identification using standardized evaporative fraction: Perspective from surface energy partitioning},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134609},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134609}
}