Olmo M. E. auteur aut IRD Espinoza J. C. auteur aut IRD Bettolli M. L. auteur aut IRD Sierra J. P. auteur aut IRD Junquas Clémentine auteur aut IRD Arias P. A. auteur aut IRD Moron V. auteur aut IRD Balmaceda-Huarte R. auteur aut IRD text journalArticle eng text/pdf born digital access The representation of the South American Monsoon System (SAMS) by general circulation models (GCMs) is of key relevance for a better understanding of the physical rationale behind the recent climate changes over South Tropical South America (STSA) and their expected changes in a global warming scenario. During the last four decades, STSA experienced a lengthening of the dry season associated with diverse forcings. In this work, a set of 16 GCMs historical Coupled Model Intercomparison Project Phase 6 coupled simulations were evaluated during 1979-2014 in terms of how well they reproduced the atmospheric circulation over STSA through a circulation-patterns (CPs) approach. Nine CPs were first identified based on low-level winds from the ERA5 reanalysis. Focus was put on the representation of CPs during the dry-to-wet transition season (July-October). Model performance depended on the seasonal cycle and spatial structure of the CPs. GCMs adequately reproduced the different CPs, with lower skills in the transition seasons. GCMs tended to go from dry to wet conditions too quickly, evidencing deficiencies in the representation of the SAMS onset, related to a poor representation of the southerly wind intrusions to STSA and the variability of the South American low-level jet. Some GCMs were able to associate the occurrence of anomalous dry and wet years with specific CPs, suggesting well-represented physical mechanisms controlling precipitation variability. This study could identify a few GCMs that adequately simulated the CPs in STSA (among them, CESM2, CMCC-CM2-HR4 and MPI-ESM1-2-HR), which is relevant for driving high-resolution models and the analysis of future projections. specialized Amazon region circulation patterns South American monsoon precipitation general circulation models CMIP6 AMERIQUE DU SUD ZONE TROPICALE 021 020 127 12 e2022JD036468 [20 ] 2022 2169-897X https://www.documentation.ird.fr/hor/fdi:010085264 10.1029/2022jd036468 2169-897X [F B010085264] https://www.documentation.ird.fr/hor/fdi:010085264 https://www.documentation.ird.fr/intranet/publi/2022-09/010085264.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2022-09-02 2025-02-24 fdi:010085264 fre