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AGU: Geophysical Research Letters

 

Keywords

  • multidecadal climate variability
  • deglaciation
  • marine sediments

Index Terms

  • Biogeosciences: Paleoclimatology and paleoceanography
  • Paleoceanography: Continental climate records
  • Paleoceanography: Thermohaline
  • Oceanography: Biological and Chemical: Geochemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L21707, 5 PP., 2009
doi:10.1029/2009GL039914

Possible impact of the Atlantic Multidecadal Oscillation on the South American summer monsoon

Cristiano M. Chiessi

MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

Stefan Mulitza

MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

Jürgen Pätzold

MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

Gerold Wefer

MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

José A. Marengo

Center for Earth System Science, National Institute for Space Research, São José dos Campos, Brazil

The South American summer monsoon (SASM) is the main source of precipitation for the most densely populated and agriculturally productive regions of tropical and subtropical South America. Here we investigate the impact of the Atlantic Multidecadal Oscillation (AMO) on the SASM using ∼4500 yr long proxy records of the discharge variability of the La Plata River Drainage Basin (PRDB), subtropical South America. We measured the stable oxygen composition of planktic foraminifera (related to the extension of the PRDB plume), and Ti intensity in bulk sediment (related to the source of the terrigenous sediments) from a marine sediment core. Spectral and wavelet analyses of our records indicate an oscillation with period of ∼64 yr. We conclude that the observed oscillation reflects variability in the SASM activity associated to the AMO. Sea surface temperature and atmospheric circulation anomalies triggered by the AMO would control the variability in SASM activity.

Received 8 July 2009; accepted 30 September 2009; published 6 November 2009.

Citation: Chiessi, C. M., S. Mulitza, J. Pätzold, G. Wefer, and J. A. Marengo (2009), Possible impact of the Atlantic Multidecadal Oscillation on the South American summer monsoon, Geophys. Res. Lett., 36, L21707, doi:10.1029/2009GL039914.

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