Stoffels et al. (2025) Precipitation, moisture sources and transport pathways associated with summertime North Atlantic deep cyclones

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Identification

• Journal: Repository for Publications and Research Data (ETH Zurich)
• Year: 2025
• Date: 2025-12-09
• Authors: Rikke Stoffels, Imme Benedict, Lukas Papritz, Frank Selten, Chris Weijenborg
• DOI: 10.3929/ethz-c-000789954

Research Groups

Not specified in the provided text.

Short Summary

This study investigates how summertime extratropical cyclones influence the water cycle by identifying their moisture sources and transport pathways. It finds that precipitation primarily occurs near the cyclone center during intensification, sourced from high ocean evaporation regions and some continental areas, with moisture residence time remaining constant at approximately 4 days throughout the cyclone's life cycle.

Objective

• To improve understanding of how summertime extratropical cyclones shape the characteristics of the water cycle, focusing on their moisture sources and the transport of moisture to cyclone centers.

Study Configuration

• Spatial Scale: North Atlantic
• Temporal Scale: Summertime cyclones; 8-day backward trajectories; analysis across the cyclone life cycle.

Methodology and Data

• Models used: WaterSip (moisture source diagnostic)
• Data sources: ERA5 reanalysis data

Main Results

• The bulk of precipitation associated with summertime cyclones falls close to the cyclone center beneath the warm conveyor belt (WCB) and along the fronts, mainly during the cyclone's intensification phase.
• Moisture originates from areas of high ocean evaporation, with significant hotspots on the warm side of the Gulf Stream Front, and from continental sources, especially for cyclones in the Labrador Sea.
• Moisture uptake occurs primarily in regions with strong sea surface temperature (SST) gradients inducing intense ocean evaporation and during cold-air advection within the cyclone's cold sector, where oceanic evaporation is enhanced due to strong air-sea temperature contrast.
• Moisture accumulated in the cold sector can act as a source for subsequent cyclones.
• As cyclones mature, distances between the moisture source and the location where moisture precipitates decrease, but the atmospheric residence time of moisture remains approximately 4 days throughout the cyclone life cycle.
• Compared to winter cyclones, summer cyclones show greater moisture supply from continental sources and significant influence from tropical cyclones undergoing extratropical transition, while winter cyclones have more moisture exchange between primary and secondary cyclones and stronger vertical ascent in the WCB.

Contributions

• Provides a detailed understanding of moisture sources and transport mechanisms for summertime extratropical cyclones, a less-studied phenomenon compared to their winter counterparts.
• Highlights present-day summer conditions as an analogue for future winter cyclones in a warmer climate, contributing to climate change impact understanding.
• Identifies specific oceanic and continental moisture hotspots and their dynamic interaction with cyclone development.

Funding

Not specified in the provided text.

Citation

@article{Stoffels2025Precipitation,
  author = {Stoffels, Rikke and Benedict, Imme and Papritz, Lukas and Selten, Frank and Weijenborg, Chris},
  title = {Precipitation, moisture sources and transport pathways associated with summertime North Atlantic deep cyclones},
  journal = {Repository for Publications and Research Data (ETH Zurich)},
  year = {2025},
  doi = {10.3929/ethz-c-000789954},
  url = {https://doi.org/10.3929/ethz-c-000789954}
}