Influence of decadal sea surface temperature variability on northern Brazil rainfall in CMIP5 simulations

Author(s)

Villamayor, Julian ^{[1, 2]} ; Ambrizzi, Tercio ^[3] ; Mohino, Elsa ^[1]

Affiliation

^[1] Univ Complutense Madrid, Fac CC Fis, Dept Geofis & Meteorol, Pza Ciencias, E-28040 Madrid - Spain

^[2] Inst Geociencias IGEO, Madrid - Spain

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo - Brazil

• Document type: Journal article
• Source: Climate Dynamics; v. 51, n. 1-2, p. 563-579, JUL 2018.
• Web of Science Citations: 1

Abstract

The Amazonia and Northeast regions of northern Brazil are characterized by very different rainfall regimes but have certain similarities in terms of their variability. The precipitation variability in both regions is strongly linked to the tropical Atlantic sea surface temperature (SST) gradient and the tropical Pacific SST anomalies, which at decadal timescales are modulated by the Atlantic Multidecadal Variability (AMV) and the Interdecadal Pacific Oscillation (IPO) modes of SST, respectively. On the other hand, it has been found that state-of-the-art models from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) are able to reproduce some of the characteristics of the low-frequency SST variability modes. In this work we analyze how CMIP5 models simulate the observed response of precipitation in the Amazonia and Northeast regions to the AMV and the IPO and the atmospheric mechanisms involved. Results show that, in both CMIP5 simulations and observations, Amazonia and Northeast rainfall response to the AMV is the opposite, due to the modulation of the intertropical convergence zone (ITCZ) position. Conversely, the IPO affects equally both regions as a consequence of anomalous subsidence over the entire northern Brazil triggered by warm SST anomalies in the tropical Pacific. Such results suggest that an improvement of the predictability of decadal SST modes will directly revert into a better prediction of changes in the Amazonia and Northeast rainfall at longer timescales. (AU)

• FAPESP's process: 13/50521-7 - Multi-scale processes driving tropical convection and influence of the aerosol
• Grantee: Tercio Ambrizzi
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 08/58101-9 - Impact of the Southwestern Atlantic Ocean on South American climate for the 20th and 21st centuries
• Grantee: Tercio Ambrizzi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants