Agosta et al. (2026) From dynamic control to thermodynamic amplification: The structural redistribution of Iberian precipitation (1950–2024)

Identification

• Journal: Atmospheric Research
• Year: 2026
• Date: 2026-04-01
• Authors: Eduardo A. Agosta, David Corell, Javier J. Miró, María José Estrela
• DOI: 10.1016/j.atmosres.2026.108985

Research Groups

• “Departamento de Ecología Integral Conferencia Episcopal Española” [Integral Ecology Department, Spanish Catholic Bishops' Conference]
• Grupo CLIMAMET, Departamento de Geografía, Facultad de Geografía e Historia, Universidad de Valencia [CLIMAMET Group, Department of Geography, Faculty of Geography and History, University of Valencia]
• Departamento de Análisis Geográfico Regional y Geografía Física, Universidad de Alicante [Department of Regional Geographical Analysis and Physical Geography, University of Alicante]

Short Summary

This study evaluates the hydroclimatic transition of the Iberian Peninsula (1950–2024), revealing a structural redistribution of precipitation where total volume remains stable but extreme precipitation intensifies, particularly along coasts, driven by thermodynamic amplification in a moisture-enriched environment.

Objective

• To comprehensively evaluate the hydroclimatic transition of the Iberian Peninsula (1950–2024), characterizing its spatial structure and temporal evolution.
• To determine the drivers of the observed shift in precipitation patterns, specifically the intensification of extreme precipitation.

Study Configuration

• Spatial Scale: Iberian Peninsula
• Temporal Scale: 1950–2024 (75 years)

Methodology and Data

• Models used: Stepwise regression models
• Data sources: ERA5 atmospheric water balances, high-density station observations

Main Results

• The Iberian Peninsula is undergoing a structural redistribution of precipitation, with total precipitation volume remaining statistically unchanged.
• The region is transitioning toward a moisture-limited sink, characterized by declining surface evaporation and rising atmospheric evaporative demand.
• Volumetric stability of total precipitation is observed across 90.5% of the territory.
• A zero-sum redistribution is occurring: the fractional contribution of extreme precipitation (Rp95) has systematically increased relative to ordinary rainfall (Ro) across 29.6% of the observational network, intensifying along the coasts while ordinary rainfall declines inland.
• Stationary frequency of large-scale circulation patterns (NAO, WeMO, subtropical ridges, blocks) explains the long-term stability of total precipitation volume but does not account for the intensification of extremes.
• Distinct seasonal mechanisms are observed: winter extremes show an amplification of dynamic efficiency, while autumn extremes (Rp95) are entirely uncoupled from large-scale circulation.
• The intensification of autumn extremes has accelerated significantly in the recent period (1988–2024).
• The results provide diagnostic evidence consistent with thermodynamic amplification, where stable dynamic triggers act as more efficient triggers in a moisture-enriched environment (due to increased total column water vapor), enhancing coastal extremes.

Contributions

• Provides comprehensive observational evidence of a structural redistribution of precipitation in the Iberian Peninsula, where total volume stability masks an intensification of extreme events.
• Diagnoses the underlying mechanisms, distinguishing between dynamic control for total precipitation and thermodynamic amplification for extreme events, particularly uncoupled autumn extremes.
• Highlights the role of increased total column water vapor in driving the enhanced efficiency of classical synoptic configurations, leading to a more extreme and hydrologically volatile regime.

Funding

• Not available in the provided text.

Citation

@article{Agosta2026From,
  author = {Agosta, Eduardo A. and Corell, David and Miró, Javier J. and Estrela, María José},
  title = {From dynamic control to thermodynamic amplification: The structural redistribution of Iberian precipitation (1950–2024)},
  journal = {Atmospheric Research},
  year = {2026},
  doi = {10.1016/j.atmosres.2026.108985},
  url = {https://doi.org/10.1016/j.atmosres.2026.108985}
}