Gilmour et al. (2025) Mesoscale Convective Systems over South America: Representation in Kilometer-Scale Met Office Unified Model Climate Simulations

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

Identification

• Journal: Journal of Climate
• Year: 2025
• Date: 2025-12-04
• Authors: Harriet Gilmour, Robin Chadwick, Jennifer L. Catto, Kate Halladay, Neil Hart, Amanda Rehbein
• DOI: 10.1175/jcli-d-24-0754.1

Research Groups

• Met Office

Short Summary

This study assesses the representation of mesoscale convective systems (MCSs) in multiyear convection-permitting regional climate model simulations over South America against satellite observations. It finds that while simulations capture MCS climatology well, they show biases in frequency (overestimated in Amazon, underestimated in La Plata basin) and precipitation characteristics (overestimated intensity, underestimated area), leading to an underestimation of MCS contribution to total rainfall.

Objective

• To assess the representation of simulated present-day mesoscale convective systems (MCSs) in convection-permitting regional climate model simulations over South America compared with satellite observations.

Study Configuration

• Spatial Scale: South America, kilometer-scale resolution.
• Temporal Scale: Multiyear simulations, focusing on present-day MCS climatology.

Methodology and Data

• Models used: South America Convection-Permitting Regional Climate Model (SA-CPRCM) simulations (Met Office kilometer-scale climate simulations).
• Data sources: Satellite observations, processed using the Tracking and Object-Based Analysis of Clouds (tobac) algorithm.

Main Results

• Simulations effectively capture the observed MCS climatology, including spatial distribution patterns and diurnal and seasonal cycles.
• MCS frequency is overestimated over the Amazon basin by a factor of 1.5.
• MCS frequency is underestimated over the La Plata basin, with a smaller bias, likely due to weaker simulated moisture flux.
• Regional variations in MCS characteristics are generally well simulated.
• Simulated MCSs overestimate precipitation intensity by a factor of 1.5–2.
• Simulated MCSs underestimate precipitation area by a factor of 2–2.5.
• The model underestimates the MCS contribution to total rainfall by 20%–30%, particularly in subtropical South America.

Contributions

• Provides an evaluation of mesoscale convective system representation in Met Office kilometer-scale simulations over South America.
• Highlights the benefits and limitations of using these convection-permitting climate simulations for MCSs in the region.
• Contributes to a broader understanding of modeling challenges for high-impact weather events like MCSs, which are poorly represented in global climate models.

Funding

• Not specified in the abstract.

Citation

@article{Gilmour2025Mesoscale,
  author = {Gilmour, Harriet and Chadwick, Robin and Catto, Jennifer L. and Halladay, Kate and Hart, Neil and Rehbein, Amanda},
  title = {Mesoscale Convective Systems over South America: Representation in Kilometer-Scale Met Office Unified Model Climate Simulations},
  journal = {Journal of Climate},
  year = {2025},
  doi = {10.1175/jcli-d-24-0754.1},
  url = {https://doi.org/10.1175/jcli-d-24-0754.1}
}