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AGU: Geophysical Research Letters

 

Keywords

  • SST
  • feedback
  • SACZ

Index Terms

  • Atmospheric Processes: Ocean/atmosphere interactions
  • Oceanography: Physical: Air/sea interactions
  • Oceanography: General: Ocean predictability and prediction

Abstract

Negative ocean-atmosphere feedback in the South Atlantic Convergence Zone

R. A. F. De Almeida

Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, Brazil

P. Nobre

Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, Brazil

R. J. Haarsma

Royal Netherlands Meteorological Institute, De Bilt, Netherlands

E. J. D. Campos

Instituto Oceanográfico, Universidade de São Paulo, São Paulo, Brazil

The temporal evolution of the coupled variability between the South Atlantic Convergence Zone (SACZ) and the underlying sea surface temperature (SST) during austral summer is investigated using monthly data from the NCEP/NCAR reanalysis. A maximum covariance analysis shows that the SACZ is intensified [weakened] by warm [cold] SST anomalies in the beginning of summer, drifting northward. This migration is accompanied by the cooling [warming] of the original oceanic anomalies. The results confirm earlier analyses using numerical models that suggest the existence of a negative feedback between the SACZ and the underlying South Atlantic SST field. A linear regression of daily anomalies of SST and omega at 500 hPa to the equations of a stochastic oscillator reveals a negative ocean–atmosphere feedback in the western South Atlantic, stronger during January and February directly underneath the oceanic band of the SACZ.

Received 17 April 2007; accepted 2 August 2007; published 21 September 2007.

Citation: De Almeida, R. A. F., P. Nobre, R. J. Haarsma, and E. J. D. Campos (2007), Negative ocean-atmosphere feedback in the South Atlantic Convergence Zone, Geophys. Res. Lett., 34, L18809, doi:10.1029/2007GL030401.

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