Duan et al. (2025) The Impact of Soil Preconditioning on the Evolution of Heatwaves Under Constrained Circulation: A Case Study of the 2021 Pacific Northwest Heatwave

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Identification

• Journal: Earth s Future
• Year: 2025
• Date: 2025-09-01
• Authors: Suqin Q. Duan, Karen A. McKinnon, Isla R. Simpson
• DOI: 10.1029/2025ef006216

Research Groups

Not specified in the provided text.

Short Summary

This study utilizes CESM2 ensemble simulations to evaluate the role of initial soil moisture and land-atmosphere interactions in the June 2021 Pacific Northwest heatwave, finding that while circulation is the primary driver, soil moisture state significantly modulates the event's intensity and duration.

Objective

• To assess the influence of prior soil moisture (SM) and evaporative regimes on the temporal evolution and magnitude of the 2021 Pacific Northwest heatwave.

Study Configuration

• Spatial Scale: Pacific Northwest (PNW) region.
• Temporal Scale: Late June 2021 (event-specific) and future climate projections.

Methodology and Data

• Models used: Community Earth System Model version 2 (CESM2).
• Data sources: Observational data (used to constrain circulation outside the PNW region).

Main Results

• Large-scale circulation is the dominant driver, producing peak temperatures approximately $17\text{ K}$ above the climatological mean.
• Perturbations in initial soil moisture preconditioning result in a temperature spread of approximately $3\text{ K}$ across ensemble members.
• Land-atmosphere interactions evolve based on a critical soil moisture threshold; crossing this threshold leads to a substantial reduction in evapotranspiration.
• In future climate scenarios (higher greenhouse gases and drier soils), there is an increased probability of shifting from a wet to a transitional evaporative regime, which exacerbates and prolongs heatwave events.

Contributions

• Quantifies the specific contribution of soil moisture preconditioning to the intensity of the 2021 PNW heatwave.
• Identifies the role of critical soil moisture thresholds in triggering shifts in evaporative regimes.
• Projects the impact of future climate change on the probability and severity of land-atmosphere feedback during extreme heat events.

Funding

Not specified in the provided text.

Citation

@article{Duan2025Impact,
  author = {Duan, Suqin Q. and McKinnon, Karen A. and Simpson, Isla R.},
  title = {The Impact of Soil Preconditioning on the Evolution of Heatwaves Under Constrained Circulation: A Case Study of the 2021 Pacific Northwest Heatwave},
  journal = {Earth s Future},
  year = {2025},
  doi = {10.1029/2025ef006216},
  url = {https://doi.org/10.1029/2025ef006216}
}