Polls et al. (2026) Observed Effects of Near-Surface Relative Humidity on Rainfall Microphysics During the LIAISE Field Campaign

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

Identification

• Journal: Remote Sensing
• Year: 2026
• Date: 2026-02-05
• Authors: Francesc Polls, Joan Bech, Mireia Udina, Eric Peinó, Albert García-Benadí
• DOI: 10.3390/rs18030509

Research Groups

Participants of the LIAISE field campaign in NE Spain.

Short Summary

This study investigates how near-surface relative humidity influences early-stage rainfall characteristics, finding that dry conditions lead to longer precipitation descent times, fewer small drops, and higher surface radar reflectivity compared to moist conditions, despite similar surface rainfall amounts.

Objective

• To investigate how near-surface relative humidity influences early-stage rainfall characteristics when precipitation is most affected by temperature and relative humidity before rainfall onset.

Study Configuration

• Spatial Scale: Two instrumented sites in NE Spain.
• Temporal Scale: May–September 2021.

Methodology and Data

• Models used: No explicit models for simulation or prediction were used; rainfall events were classified as stratiform or convective using weather radar data based on a texture analysis of the reflectivity field. Stratiform events were further classified into dry and moist categories based on near-surface (2 m) relative humidity terciles (dry < 54%; moist > 72%).
• Data sources: Disdrometers, Micro Rain Radar (MRR), C-band weather radar data, and automatic weather stations.

Main Results

• During dry events, the time delay between precipitation detection at approximately 750 meters above ground level (AGL) (by MRR or C-band radar) and its arrival at the surface (measured by disdrometer) is consistently longer than during moist events, suggesting raindrop evaporation during descent.
• Surface drop size distributions differ, with dry cases generally having fewer small drops (with diameters less than 0.8 mm) but relatively more large drops.
• This leads to higher radar reflectivity values at the surface during dry events, even with similar surface rainfall amounts.
• Reflectivity observed aloft by C-band radar and MRR does not exhibit the same dependence on relative humidity found at ground level.

Contributions

• Increases understanding of the impact of low-level atmospheric conditions on precipitation characteristics and associated microphysical processes.
• May contribute to improving correction schemes in operational weather radar quantitative precipitation estimates.

Funding

Conducted within the framework of the LIAISE field campaign. Specific funding projects, programs, and reference codes are not detailed in the provided text.

Citation

@article{Polls2026Observed,
  author = {Polls, Francesc and Bech, Joan and Udina, Mireia and Peinó, Eric and García-Benadí, Albert},
  title = {Observed Effects of Near-Surface Relative Humidity on Rainfall Microphysics During the LIAISE Field Campaign},
  journal = {Remote Sensing},
  year = {2026},
  doi = {10.3390/rs18030509},
  url = {https://doi.org/10.3390/rs18030509}
}