Chadwick et al. (2025) Processes Controlling the South American Monsoon Response to Climate Change

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

Identification

• Journal: Journal of Climate
• Year: 2025
• Date: 2025-11-10
• Authors: Robin Chadwick, Peter Good, Jorge L. García‐Franco, Lincoln Muniz Alves, Neil Hart, Marcia Zilli, Hervé Douville, Marion Saint‐Lu, Brian Medeiros
• DOI: 10.1175/jcli-d-25-0012.1

Research Groups

Not specified in the abstract.

Short Summary

Future projections consistently show early South American monsoon drying, primarily driven by sea surface temperature (SST) changes (uniform warming and patterned changes), with Atlantic SST gradients explaining over half of the intermodel uncertainty in November.

Objective

• To investigate the drivers of projected early South American monsoon precipitation drying in CMIP6 models and a convection-permitting simulation, specifically focusing on the roles of uniform and patterned sea surface temperature changes.

Study Configuration

• Spatial Scale: South America (SA monsoon core region), Atlantic Ocean (for SST gradients).
• Temporal Scale: Early monsoon season (September–November), future projections.

Methodology and Data

• Models used: Coupled Model Intercomparison Project phase 6 (CMIP6) models, convection-permitting model, idealized atmosphere-only general circulation model (GCM) experiments.
• Data sources: CMIP6 model outputs, convection-permitting model simulation results.

Main Results

• Future projections consistently show drying in the early South American monsoon season (September–November).
• This drying signal is mainly driven by sea surface temperature (SST) changes: uniform SST warming and patterned SST change.
• SST pattern change is primarily important in October, while uniform SST warming is more important in November for the ensemble mean drying.
• The hypothesis that SA monsoon drying is driven by enhanced land–sea temperature contrast due to uniform SST warming is not found to be dominant.
• Moderate intermodel correlations exist between SA monsoon precipitation change and changes in meridional and zonal Atlantic SST gradients for patterned SST warming.
• In November, a combined zonal and meridional Atlantic SST gradient index can explain more than 50% of CMIP6 intermodel uncertainty in SA monsoon core region precipitation change.

Contributions

• Identifies uniform SST warming and patterned SST changes as the main drivers of projected early SA monsoon drying.
• Differentiates the relative importance of these drivers across different months (October vs. November).
• Refutes the dominance of the enhanced land-sea temperature contrast hypothesis for uniform SST warming.
• Quantifies the role of Atlantic SST gradients in explaining a significant portion (>50%) of intermodel uncertainty in SA monsoon precipitation change, particularly in November.

Funding

Not specified in the abstract.

Citation

@article{Chadwick2025Processes,
  author = {Chadwick, Robin and Good, Peter and García‐Franco, Jorge L. and Alves, Lincoln Muniz and Hart, Neil and Zilli, Marcia and Douville, Hervé and Saint‐Lu, Marion and Medeiros, Brian},
  title = {Processes Controlling the South American Monsoon Response to Climate Change},
  journal = {Journal of Climate},
  year = {2025},
  doi = {10.1175/jcli-d-25-0012.1},
  url = {https://doi.org/10.1175/jcli-d-25-0012.1}
}