Theoretical and Applied Climatology

, Volume 101, Issue 3, pp 303–310

Summertime moisture transport over Southeastern South America and extratropical cyclones behavior during inter-El Niño events

  • Gyrlene Aparecida Mendes da Silva
  • T. Ambrizzi
Original Paper

DOI: 10.1007/s00704-009-0218-6

Cite this article as:
Silva, G.A.M. & Ambrizzi, T. Theor Appl Climatol (2010) 101: 303. doi:10.1007/s00704-009-0218-6

Abstract

The impact of the inter-El Niño (EN) variability on the moisture availability over Southeastern South America (SESA) is investigated. Also, an automatic tracking scheme was used to analyze the extratropical cyclones properties (system density - SD and central pressure - CP) in this region. During the austral summer period from 1977–2000, the differences for the upper-level wave train anomaly composites seem to determine the rainfall composite differences. In fact, the positive rainfall anomalies over most of the SESA domain during the strong EN events are explained by an upper-level cyclonic center over the tropics and an anticyclonic center over the eastern subtropical area. This pattern seems to contribute to upward vertical motion at 500 hPa and reinforcement of the meridional moisture transport from the equatorial Atlantic Ocean and western Amazon basin to the SESA region. These features may contribute to the positive SD and negative CP anomalies explaining part of the positive rainfall anomalies found there. On the other hand, negative rainfall anomalies are located in the northern part of SESA for the weak EN years when compared to those for the strong events. Also, positive anomalies are found in the southern part, albeit less intense. It was associated with the weakening of the meridional moisture transport from the tropics to the SESA that seems have to contributed with smaller SD and CP anomalies over the most part of subtropics, when compared to the strong EN years.

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Gyrlene Aparecida Mendes da Silva
    • 1
  • T. Ambrizzi
    • 1
  1. 1.Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric SciencesUniversity of São PauloSão PauloBrazil05508-090