Rixen et al. (2025) Influence of Mesoscale Organization on the Formation of Humidity Haloes

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

Identification

• Journal: Repository for Publications and Research Data (ETH Zurich)
• Year: 2025
• Date: 2025-11-28
• Authors: Rixen, Marius, Windmiller, Julia, Stevens, Bjorn
• DOI: 10.3929/ethz-c-000788368

Research Groups

Not explicitly stated in the provided text.

Short Summary

This study investigates humidity haloes around trade wind shallow cumulus clouds using observatory data, finding they increase downward longwave radiation by 10 W/m² and are primarily driven by mesoscale organization rather than single-cloud detrainment.

Objective

• To analyze the radiative environment around shallow cumulus clouds, specifically focusing on humidity haloes and their influence on downward longwave radiation.
• To examine the cause of humidity halo formation.

Study Configuration

• Spatial Scale: Localized around shallow cumulus clouds, with observations extending up to 1 kilometer from the clouds.
• Temporal Scale: Continuous observation of the radiative environment around clouds.

Methodology and Data

• Models used: Not explicitly stated, but a rough mass flux estimate was performed.
• Data sources: Barbados Cloud Observatory (longwave radiation measurements), co-located CORAL LiDAR instrument (moisture profiles).

Main Results

• Humidity haloes, regions of enhanced water vapor, were observed up to a distance of 1 kilometer from shallow cumulus clouds.
• These humidity haloes cause an average increase in downward longwave radiation of 10 watts per square meter (W/m²).
• Detrainment from a single cloud alone is insufficient to explain the formation of these humidity haloes.
• Mesoscale organization is suggested to play a key role in modulating boundary layer moisture and increasing humidity around clouds.

Contributions

• Provides observational evidence and quantification of the radiative impact of humidity haloes around shallow cumulus clouds using ground-based data.
• Offers insights into the formation mechanism of humidity haloes, suggesting the dominant role of mesoscale organization over single-cloud detrainment.
• Confirms consistency with previous satellite-based observational estimates of radiative impact.

Funding

Not explicitly stated in the provided text.

Citation

@article{Rixen2025Influence,
  author = {Rixen, Marius and Windmiller, Julia and Stevens, Bjorn},
  title = {Influence of Mesoscale Organization on the Formation of Humidity Haloes},
  journal = {Repository for Publications and Research Data (ETH Zurich)},
  year = {2025},
  doi = {10.3929/ethz-c-000788368},
  url = {https://doi.org/10.3929/ethz-c-000788368}
}