Seasonal changes of the South American monsoon system during the Mid-Holocene in the CMIP5 simulations

Autor(es)

Shimizu, M. H. ^[1] ; Sampaio, G. ^[1] ; Venancio, I. M. ^[1] ; Maksic, J. ^[1]

Afiliação do(s) autor(es)

^[1] Natl Inst Space Res, Ctr Weather Forecasting & Climate Studies, Cachoeira Paulista, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Climate Dynamics; v. 54, n. 5-6, p. 2697-2712, MAR 2020.
• Citações Web of Science: 0

Resumo

The South American Monsoon System (SAMS) is a major climatic feature of South America, and its domain extends from Amazon to La Plata basin. The SAMS region is vulnerable to variations of climate and precipitation patterns, which could impact economic activities and lead to potential societal consequences. In the face of a warming future scenario, the importance of the study of the past climate with numerical simulations is to evaluate the climate models and to assure the reliability of future projections. Here we investigate the Mid-Holocene SAMS, evaluating changes in strength, life cycle and associated dynamical mechanisms in ten Earth System Models simulations. Our results show that the SAMS was weaker in the Mid-Holocene than in the pre-industrial climate in December-January-February (DJF), but stronger in September-October-November (SON). This is probably a consequence of insolation variations in the Mid-Holocene, which contributed to changes in the moisture flux from the Atlantic Ocean to the continent, the strength of the upper-level atmospheric circulation, and the amount of precipitation over the SAMS region. Moreover, we suggest that the life cycle of the SAMS was altered during the Mid-Holocene, with an earlier onset and demise. Our results also indicate that Mid-Holocene SAMS changes are connected to precipitation variations near Northeast Brazil, in a dipole configuration of precipitation between western Amazon and Northeast Brazil, due to the influence of the Walker cell. Finally, this study highlights a need for improvement of the numerical models to better simulate the amount of precipitation over South America and the upper-level circulation over western Amazon in SON, which are crucial factors for a more realistic representation of the SAMS. (AU)

• Processo FAPESP: 16/24014-9 - Avaliação da variabilidade interanual a multidecadal do sistema de monção da América do Sul através de simulações numéricas do clima passado
• Beneficiário: Marilia Harumi Shimizu
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico