Sokol et al. (2025) Estimating changes in precipitation event characteristics with projected temperature increase in the 21st century

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-12-12
• Authors: Zbyněk Sokol, Daniela Řezáčová, Jana Popová
• DOI: 10.1016/j.atmosres.2025.108698

Research Groups

• Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
• Faculty of Science, Charles University, Prague, Czech Republic

Short Summary

This study investigates how precipitation event characteristics (duration, frequency, total, mean, and maximum precipitation) change with increasing ground temperature in the Czech Republic during the warm season of the 21st century, using observed, reanalysed, and high-resolution climate model projections. It finds that while precipitation totals increase with temperature up to a certain point before decreasing, the duration of precipitation events does not exhibit any significant change with rising temperature.

Objective

• To investigate how the duration and four calculated characteristics of precipitation events change in relation to the projected increase in ground temperature during the 21st century in the warm part of the year.

Study Configuration

• Spatial Scale: Czech Republic, using data from 97 meteorological stations and model simulations with a horizontal resolution of 2.3 km.
• Temporal Scale:
  • Observations: 1998–2014 (April–September), hourly data.
  • Reanalysis: 1990–2014 (April–September), hourly data.
  • Projections: 2026–2100 (April–September), hourly data, divided into three 25-year periods (2026–2050, 2051–2075, 2076–2100).

Methodology and Data

• Models used:
  • ALADIN-CZ numerical weather prediction (NWP) model (for reanalysis).
  • ALADIN-CLIMAT-CZ regional climate model (for projections).
  • Both are convection-permitting models with a horizontal resolution of 2.3 km.
• Data sources:
  • Measured hourly precipitation totals and 2 m ground temperature from 97 rain gauge stations in the Czech Republic (CLIDATA database).
  • Hourly precipitation and 2 m ground temperature from ALADIN-CZ NWP model reanalysis, coupled with ERA5.
  • Hourly precipitation and 2 m ground temperature projected by the ALADIN-CLIMAT-CZ climate model for two CMIP6 scenarios: SSP2-4.5 ("middle of the road") and SSP5-8.5 ("very high baseline emission").
  • A precipitation event (PE) was defined as a continuous sequence of hourly precipitation values of at least 0.2 mm/h, with a duration from 1 to 23 hours.
  • Four characteristics of PEs were analyzed: relative frequency (F), relative total precipitation (Fw), relative mean precipitation (Fmean), and relative maximum precipitation (Fmax).
  • Ground temperature measured one hour before the onset of precipitation was used to minimize the influence of precipitation on temperature.

Main Results

• Observed PEs (1998-2014): The number of PEs and total precipitation increase with temperature up to approximately 14–15 °C, then decrease. Most frequent PEs are 1–5 hours long, occurring between 14–17 °C. Relative mean precipitation shows highest values for longer PEs (>17 hours) at cooler temperatures (<16 °C).
• Reanalysed PEs (1990-2014): Show generally consistent characteristics with observed PEs but occur over a wider temperature range. Reanalysis indicates longer PEs at higher temperatures where observations show none. The total mean precipitation (6.58 mm) is very similar to observations (6.24 mm), but the maximum precipitation (67.8 mm) is significantly lower than observed (130.8 mm).
• Projected PEs (2026-2100): Results are consistent with reanalysed PEs. The SSP5-8.5 scenario projects higher precipitation amounts than SSP2-4.5, with precipitation increasing further into the future under SSP5-8.5.
• Key Finding: The duration of precipitation events does not exhibit any significant change with increasing temperature in future projections; most frequent PEs remain 2–3 hours long.
• High precipitation totals do not occur at very high temperatures; they increase with temperature up to a certain "tipping point" and then decrease, with this tipping point being higher for projected precipitation and scenario-dependent.

Contributions

• Introduces a novel event-based approach to analyze precipitation characteristics (frequency, total, mean, maximum) in relation to duration and pre-event ground temperature.
• Utilizes high-resolution (2.3 km) convection-permitting regional climate models (ALADIN-CZ, ALADIN-CLIMAT-CZ) for reanalysis and future projections over the Czech Republic.
• Provides a comprehensive comparison of observed, reanalysed, and projected precipitation event characteristics, highlighting model biases and consistencies.
• Demonstrates that while precipitation intensity may change with temperature (up to a tipping point), the duration of precipitation events is projected to remain largely unaffected by increasing temperatures in the 21st century.
• Emphasizes the importance of using pre-event ground temperature to avoid precipitation-induced cooling effects on temperature-precipitation relationships.

Funding

• Technology Agency of the Czech Republic (grant no. SS02030040, PERUN)
• Johannes Amos Comenius Programme (P JAC), project No. CZ.02.01.01/00/22_008/0004605, Natural and anthropogenic georisks

Citation

@article{Sokol2025Estimating,
  author = {Sokol, Zbyněk and Řezáčová, Daniela and Popová, Jana},
  title = {Estimating changes in precipitation event characteristics with projected temperature increase in the 21st century},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108698},
  url = {https://doi.org/10.1016/j.atmosres.2025.108698}
}