Propagation of Strong Rainfall Events from Southeastern South America to the Central Andes

Author(s)

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

Affiliation

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

^[2] Potsdam Inst Climate Impact Res, D-14412 Potsdam, Brandenburg - Germany

^[3] Univ Sao Paulo, Inst Phys, Sao Paulo - Brazil

^[4] Univ Potsdam, Inst Earth & Environm Sci, Potsdam - Germany

^[5] Ctr Monitoring & Early Warning Nat Disasters CEMA, Sao Paulo - Brazil

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

• Document type: Journal article
• Source: Journal of Climate; v. 28, n. 19, p. 7641-7658, OCT 2015.
• Web of Science Citations: 8

Abstract

Based on high-spatiotemporal-resolution data, the authors perform a climatological study of strong rainfall events propagating from southeastern South America to the eastern slopes of the central Andes during the monsoon season. These events account for up to 70% of total seasonal rainfall in these areas. They are of societal relevance because of associated natural hazards in the form of floods and landslides, and they form an intriguing climatic phenomenon, because they propagate against the direction of the low-level moisture flow from the tropics. The responsible synoptic mechanism is analyzed using suitable composites of the relevant atmospheric variables with high temporal resolution. The results suggest that the low-level inflow from the tropics, while important for maintaining sufficient moisture in the area of rainfall, does not initiate the formation of rainfall clusters. Instead, alternating low and high pressure anomalies in midlatitudes, which are associated with an eastward-moving Rossby wave train, in combination with the northwestern Argentinean low, create favorable pressure and wind conditions for frontogenesis and subsequent precipitation events propagating from southeastern South America toward the Bolivian Andes. (AU)

• FAPESP's process: 13/50538-7 - Understanding the causes of the biases that determine the onset of the rainy season in Amazonia in climate models using GoAmazon-CHUVA measurements
• Grantee: Jose Antonio Marengo Orsini
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/50151-0 - Dynamical phenomena in complex networks: fundamentals and applications
• Grantee: Elbert Einstein Nehrer Macau
• Support Opportunities: Research Projects - Thematic Grants