Preprints
https://doi.org/10.5194/osd-9-163-2012
https://doi.org/10.5194/osd-9-163-2012

  18 Jan 2012

18 Jan 2012

Review status: this preprint was under review for the journal OS. A revision for further review has not been submitted.

On the Atlantic cold tongue mode and the role of the Pacific ENSO

R. A. F. De Almeida and P. Nobre R. A. F. De Almeida and P. Nobre
  • National Institute for Space Research, Brazil

Abstract. The dominant mode of coupled ocean-atmosphere variability in the Tropical Atlantic is analysed in this work from a melange of datasets, focusing on the seasonal development and evolution of the Bjerknes feedback responsible for the generation of the Atlantic cold tongue mode. The strength, seasonality and interannual variability of this mode is investigated through a joint EOF analysis of the anomalies of zonal wind velocity in the western basin together with sea surface temperature from the easternmost Tropical Atlantic, and analysed in conjunction with the depth of the 20 °C isotherm, representing the three mechanisms responsible for the generation of the Bjerknes feedback. Results from the EOF analyses confirm the robustness and seasonality of the Atlantic cold tongue mode, with a positive feedback phase peaking during boreal summer when the Bjerknes feedback is stronger. Analysis of an event in 2005 shows that the positive feedback is followed by a negative feedback phase triggered by the wind field and driven by oceanic heat advection. More importantly, we investigated the linearized impact of Niño events in the Pacific Ocean over the Atlantic by projecting the NINO 3.4 index over the Atlantic data. The Atlantic cold tongue mode has its variance reduced from 62% to 47% in the projected dataset, revealing that the Pacific ENSO has an inhibiting effect over its Atlantic counterpart.

R. A. F. De Almeida and P. Nobre

 
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

R. A. F. De Almeida and P. Nobre

R. A. F. De Almeida and P. Nobre

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