The South American rainfall dipole: A complex network analysis of extreme events

Author(s)

Boers, Niklas ^{[1, 2]} ; Rheinwalt, Aljoscha ^{[1, 2]} ; Bookhagen, Bodo ^[3] ; Barbosa, Henrique M. J. ^[4] ; Marwan, Norbert ^[2] ; Marengo, Jose ^[5] ; Kurths, Juergen ^{[1, 6, 2]}

Affiliation

^[1] Humboldt Univ, Dept Phys, Berlin - Germany

^[2] Potsdam Inst Climate Impact Res, Potsdam, Brandenburg - Germany

^[3] Univ Calif Santa Barbara, Dept Geog, Santa Barbara, CA 93106 - USA

^[4] Univ Sao Paulo, Dept Phys, Sao Paulo - Brazil

^[5] Cachoeira Paulista, CCST INPE, Sao Paulo - Brazil

^[6] Nizhnii Novgorod State Univ, Dept Control Theory, Nizhnii Novgorod - Russia

• Document type: Journal article
• Source: Geophysical Research Letters; v. 41, n. 20, p. 7397-7405, OCT 28 2014.
• Web of Science Citations: 29

Abstract

Intraseasonal rainfall variability of the South American monsoon system is characterized by a pronounced dipole between southeastern South America and southeastern Brazil. Here we analyze the dynamical properties of extreme rainfall events associated with this dipole by combining a nonlinear synchronization measure with complex networks. We make the following main observations: (i) Our approach reveals the dominant synchronization pathways of extreme events for the two dipole phases, (ii) while extreme rainfall synchronization in the tropics is directly driven by the trade winds and their deflection by the Andes mountains, extreme rainfall propagation in the subtropics is mainly dictated by frontal systems, and (iii) the well-known rainfall dipole is, in fact, only the most prominent mode of an oscillatory pattern that extends over the entire continent. This provides further evidence that the influence of Rossby waves, which cause frontal systems over South America and impact large-scale circulation patterns, extends beyond the equator. (AU)

• FAPESP's process: 08/58161-1 - Assessment of impacts and vulnerability to climate change in Brazil and strategies for adaptation option
• Grantee: Jose Antonio Marengo Orsini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants