Dutheil C. auteur aut IRD Bador M. auteur aut IRD Lengaigne Matthieu auteur aut IRD Lefevre Jérôme auteur aut IRD Jourdain N. C. auteur aut IRD Vialard Jérôme auteur aut IRD Jullien S. auteur aut IRD Peltier A. auteur aut IRD Menkès Christophe auteur aut IRD text journalArticle eng text/pdf born digital access The South Pacific Convergence Zone (SPCZ) is poorly represented in global coupled simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5), with trademark biases such as the tendency to form a "double Intertropical convergence zone" and an equatorial cold tongue that extends too far westward. Such biases limit our confidence in projections of the future climate change for this region. In this study, we use a downscaling strategy based on a regional atmospheric general circulation model that accurately captures the SPCZ present-day climatology and interannual variability. More specifically, we investigate the sensitivity of the projected rainfall response to either just correcting present-day CMIP5 Sea Surface Temperature (SST) biases or correcting projected SST changes using an emergent constraint approach. While the equatorial western Pacific projected rainfall increase is robust in our experiments and CMIP5, correcting the projected CMIP5 SST changes yields a considerably larger reduction (similar to 25%) than in CMIP5 simulations (similar to + 3%) in the southwestern Pacific. Indeed, correcting the projected CMIP5 warming pattern yields stronger projected SST gradients, and more humidity convergence reduction under the SPCZ. Finally, our bias-corrected set of experiments yields an increase in equatorial rainfall and SPCZ variability in the future, but does not support the future increase in the frequency of zonal SPCZ events simulated by CMIP5 models. This study hence suggests that atmospheric downscaling studies should not only correct CMIP5 present-day SST biases but also projected SST changes to improve the reliability of their projections. Additional simulations with different physical parameterizations yield robust results. specialized Regional climate models South Pacific Convergence Zone Precipitation Sea Surface Temperature 032 53 5-6 3197-3219 2019 0930-7575 https://www.documentation.ird.fr/hor/fdi:010076654 10.1007/s00382-019-04692-6 0930-7575 [F B010076654] https://www.documentation.ird.fr/hor/fdi:010076654 https://www.documentation.ird.fr/intranet/publi/2019/09/010076654.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2019-10-14 2025-02-24 fdi:010076654 fre