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Climate Dynamics

, Volume 42, Issue 11–12, pp 3077–3086 | Cite as

The relationship between South Atlantic SST and SACZ intensity and positioning

  • Tatiana JorgettiEmail author
  • Pedro Leite da Silva Dias
  • Edmilson Dias de Freitas
Article

Abstract

This study explores the ocean–atmosphere interaction in the formation and dynamics of the South Atlantic Convergence Zone (SACZ), through the analysis of the heat sources estimated through the outgoing longwave radiation. The results obtained with this study show that the coupled variability between SACZ and the South Atlantic Ocean indicates that in northern positioned SACZ cases (over Southeastern Brazil), westerly anomalies are verified in the low level continental tropical circulation, consistent with the active phase of the South America Monsoon System (SAMS). In these cases, cold anomalies in the subtropical Atlantic Ocean cause an increase in the continent–ocean temperature gradient, favoring an easterly flow in this region, and blocking the SACZ at a northerly position. Easterly anomalies in the tropical continent were verified in the low level circulation in southern positioned cases (over Southern Brazil), consistent with the SAMS break phase. The SST anomaly patterns indicate cold anomalies in the tropics and warm anomalies in the subtropics, which do not favor the development of an easterly flow at low levels over the western tropical Atlantic. In these cases, two situations may occur: the strengthening of the Low Level Jet (LLJ), which prevails in the eastern subtropical South America and convergence with the South Atlantic Subtropical High at its southern position; or the atmospheric unstable conditions caused by ocean warm SST anomalies (in this case the LLJ may be weaker than its climatological intensity).

Keywords

South Atlantic Convergence Zone Sea-surface-temperature anomalies Atlantic dipole Singular value decomposition 

Notes

Acknowledgments

This study was supported by FAPESP (T. Jorgetti), CNPq (P. L. Silva Dias) and INCT—Mudanças Climáticas—CNPq.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Tatiana Jorgetti
    • 1
    Email author
  • Pedro Leite da Silva Dias
    • 1
    • 2
  • Edmilson Dias de Freitas
    • 1
  1. 1.Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric SciencesUniversity of São PauloSão PauloBrazil
  2. 2.National Laboratory of Scientific ComputationPetrópolisBrazil

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