Medina et al. (2026) Evaluation and projections of total and maximum-daily rainfall in Northwestern Argentina by CMIP6 models

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2026
• Date: 2026-01-01
• Authors: Franco D. Medina, Bruno S. Zossi, Ana G. Elı́as
• DOI: 10.1007/s00704-025-05995-x

Research Groups

• LIANM, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Argentina
• INFINOA (CONICET-UNT), Tucumán, Argentina

Short Summary

This study evaluates the performance of 16 CMIP6 global circulation models in simulating maximum daily (Rx1) and total (TOT) precipitation in Northwestern Argentina (NWA) and projects future changes under intermediate (SSP2-4.5) and high (SSP5-8.5) global warming scenarios. Results indicate a general increase in Rx1 by the end of the century, implying higher flood risk, alongside a projected decrease in winter and spring TOT, increasing the risk of water deficits.

Objective

• To evaluate the ability of CMIP6 models to simulate the climatology of maximum daily (Rx1) and total (TOT) seasonal and annual precipitation in Northwestern Argentina.
• To determine projected changes in mean values of Rx1 and TOT under different global warming scenarios (SSP2-4.5 and SSP5-8.5), distinguishing between models with higher and lower bias.
• To analyze the agreements and discrepancies among the projected changes across models.

Study Configuration

• Spatial Scale: Northwestern Argentina (NWA), specifically a sub-region between 22°S to 30°S latitude and 62°W to 66°W longitude, focusing on low and intermediate elevations (below 3000 m) to the eastern front of the Andes.
• Temporal Scale:
  • Historical/Reference period: 1981–2010.
  • Model historical runs: 1980–2014.
  • Near-future projections: 2025–2049.
  • Far-future projections: 2075–2099.

Methodology and Data

• Models used: 16 Global Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6).
• Data sources:
  • Observational: CPC Global Unified Gauge-Based Analysis of Daily Precipitation (CPC) by NOAA’s Climate Prediction Center (0.5° x 0.5° spatial resolution, daily temporal resolution).
  • Model data: Daily precipitation data from CMIP6 historical runs and projections under Shared Socioeconomic Pathways (SSP) SSP2-4.5 (radiative forcing of 4.5 W/m² by 2100) and SSP5-8.5 (radiative forcing of 8.5 W/m² by 2100), obtained from Earth System Grid Federation (ESGF) and Copernicus Climate Data Store (CDS).
  • Metrics: Maximum daily precipitation (Rx1) and total precipitation (TOT).
  • Evaluation: Model bias assessed using Root Mean Square Error (RMSE). Significance of projected changes assessed using Student’s t-test. Model data regridded to CPC grid using bilinear interpolation.

Main Results

• CMIP6 models generally overestimate Rx1 and TOT values in NWA, with higher biases observed in wetter seasons. The IPSL-CM6A-LR model showed the lowest bias for both Rx1 and TOT simultaneously.
• By the end of the century (far-future, 2075–2099), a general increase in Rx1 is projected for NWA, particularly for annual, DJF (December-January-February), and MAM (March-April-May) periods. Selected models project annual Rx1 increases of 20–50% under SSP5-8.5. This implies a heightened flood risk.
• A decrease in TOT is projected during the drier seasons (JJA (June-July-August) and SON (September-October-November)), exacerbating water deficits and increasing risks for precipitation-dependent economic activities.
• For TOT DJF under SSP5-8.5, a dipole-like pattern is projected, with increases in central and southern NWA and decreases in the northeastern extreme.
• Rx1 is found to be more sensitive to global warming than TOT, with projected percentage changes for Rx1 being notably higher.
• The contribution of Rx1 to TOT is projected to increase in the far-future under both SSPs, indicating a higher concentration of precipitation and a shift towards more intense, less evenly distributed rainfall.
• The increase in Rx1 is consistent with thermodynamic effects (increased atmospheric moisture), while TOT changes (decreases or non-significant changes) suggest a significant role of dynamic circulation changes.

Contributions

• This study provides the first comprehensive evaluation of CMIP6 models specifically focused on extreme precipitation (Rx1) and total precipitation (TOT) in Northwestern Argentina.
• It offers crucial, regionally-focused projections of precipitation changes, distinguishing model performance and identifying models with lower bias, which is vital for local decision-making and risk reduction strategies.
• The research highlights the differential sensitivity of Rx1 and TOT to global warming, demonstrating that extreme daily precipitation events are projected to intensify at a faster rate than total precipitation, leading to a greater concentration of rainfall.
• It contributes to understanding the physical mechanisms driving these changes, attributing Rx1 increases primarily to thermodynamic factors and TOT changes to dynamic circulation shifts.

Funding

• Research project PIP 2957 (CONICET)

Citation

@article{Medina2026Evaluation,
  author = {Medina, Franco D. and Zossi, Bruno S. and Elı́as, Ana G.},
  title = {Evaluation and projections of total and maximum-daily rainfall in Northwestern Argentina by CMIP6 models},
  journal = {Theoretical and Applied Climatology},
  year = {2026},
  doi = {10.1007/s00704-025-05995-x},
  url = {https://doi.org/10.1007/s00704-025-05995-x}
}