Zhao et al. (2026) Moisture Transport from Tropical Oceans Drives Summertime Rainfall Variability over Southwest North America

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-01-12
• Authors: Siyu Zhao, H. Zhang, Jie He
• DOI: 10.1175/jcli-d-24-0664.1

Research Groups

[Information not available in the provided abstract.]

Short Summary

This study investigates the primary sources and physical mechanisms driving summer atmospheric moisture variability over Southwest North America (SWNA) using a combined Lagrangian–Eulerian approach, revealing that tropical oceans are substantial moisture sources and wind anomalies are key drivers of moisture transport variations.

Objective

• To examine the leading sources and physical processes related to Southwest North America (SWNA) summer atmospheric moisture variability.

Study Configuration

• Spatial Scale: Southwest North America (SWNA), divided into a western Mediterranean-type climate region (region 1) and an eastern monsoonal climate region (region 2), extending to tropical oceans (subtropical Pacific, tropical Atlantic).
• Temporal Scale: Summer months (May–June, July–August, June–August), focusing on wet and dry extreme events.

Methodology and Data

• Models used: Semi-Lagrangian moisture-tracking model, Eulerian moisture budget analysis.
• Data sources: [Information not available in the provided abstract.]

Main Results

• Tropical oceans are a substantial source of summer atmospheric moisture variability over SWNA.
• The subtropical Pacific accounts for 74% (wet extremes) / 58% (dry extremes) of atmospheric moisture variations in region 1 during May–June.
• The tropical Atlantic is the leading source (83% wet extremes / 70% dry extremes) for region 2 during June–August.
• Moisture transport variations are primarily attributed to wind anomalies, though oceanic moisture anomalies can also be significant.
• Eulerian moisture budget analysis confirms that moisture advection is critical for the growth of atmospheric moisture anomalies over SWNA.
• The dynamic component of moisture advection enhances atmospheric moisture over the coastal ocean (SWNA) via anomalous southerlies (easterlies).
• The thermodynamic component transports moisture anomalies farther inland via climatological southwesterlies.
• The decline of atmospheric moisture over SWNA is associated with peak precipitation triggered by wind convergence.

Contributions

• Provides an enhanced understanding of SWNA summer moisture variability by identifying leading oceanic sources and the physical processes involved.
• Offers insights into the implications for associated rainfall predictability in the region.
• Utilizes a novel combined Lagrangian–Eulerian approach for a comprehensive analysis of atmospheric moisture dynamics.

Funding

[Information not available in the provided abstract.]

Citation

@article{Zhao2026Moisture,
  author = {Zhao, Siyu and Zhang, H. and He, Jie},
  title = {Moisture Transport from Tropical Oceans Drives Summertime Rainfall Variability over Southwest North America},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-24-0664.1},
  url = {https://doi.org/10.1175/jcli-d-24-0664.1}
}