Han et al. (2026) Decoupling dry and wet heat contributions: a station-based index for detecting regional compound heat extremes

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Identification

• Journal: Environmental Research Letters
• Year: 2026
• Date: 2026-08-18
• Authors: Ruixue Han, Yizhou Zhuang, Meng Chun Gao
• DOI: 10.1088/1748-9326/ae9b24

Research Groups

• Department of Atmospheric Science, University of Colorado Boulder
• National Center for Atmospheric Research (NCAR)

Short Summary

This study introduces the dynamic weather-climate index (DWCI), a novel framework that decomposes temperature, moisture-loading, and dry-evaporative-demand anomaly pathways to attribute contributions during compound heat events. DWCI is applied to identify 68,417 regional compound heat extremes globally from 1973-2024.

Objective

• Investigate the role of humidity in extreme heat events and develop a physically interpretable framework for compound-heat monitoring and attribution.

Study Configuration

• Spatial Scale: Global scale with focus on mid-latitude regions.
• Temporal Scale: 51-year period (1973–2024) with daily data resolution.

Methodology and Data

• Models used: None mentioned, but the study utilizes a station-based framework for DWCI development.
• Data sources: Observational datasets from various stations worldwide.

Main Results

• The dynamic weather-climate index (DWCI) captures both wet and dry heat extremes without allowing competing atmospheric pathways to cancel each other out mathematically.
• Humidity magnitude fraction accounts for 27.6% of the anomaly magnitude on regional compound heat extreme days globally, peaking in continental climates at 43.7%.
• Long-term RCHE amplification is driven primarily by widespread increases in event frequency rather than event-mean intensity.

Contributions

• The study provides a physically interpretable framework for compound-heat monitoring and attribution by separating dry and wet heat pathways.
• DWCI's ability to capture both wet and dry heat extremes without mathematical cancellation contributes to the existing literature on extreme heat events.

Funding

• This research was supported by the National Science Foundation (NSF) under grant number [not specified].

Citation

@article{Han2026Decoupling,
  author = {Han, Ruixue and Zhuang, Yizhou and Gao, Meng Chun},
  title = {Decoupling dry and wet heat contributions: a station-based index for detecting regional compound heat extremes},
  journal = {Environmental Research Letters},
  year = {2026},
  doi = {10.1088/1748-9326/ae9b24},
  url = {https://doi.org/10.1088/1748-9326/ae9b24}
}