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South Atlantic Dipole Changes From 1851 to 2010
  • Anderson Bier,
  • Tercio Ambrizzi
Anderson Bier
USP University of Sao Paulo

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Tercio Ambrizzi
USP University of Sao Paulo
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Abstract

The South Atlantic Dipole (SAD) is the main mode of coupled variability between ocean and atmosphere on interannual and interdecadal timescales on the South Atlantic Ocean. Its oceanic component is characterized by a dipole of sea surface temperature (SST) anomalies between tropics and extratropics, while the atmospheric part is linked with the South Atlantic Subtropical High (SASH) variability. Some other important factors can influence the SAD, for instance, variations in the Atlantic Meridional Overturning Circulation (AMOC), which may alter the distribution of physical properties of the ocean such as the SST. Given the current background of anthropogenic global warming, some features have contributed to alter AMOC, such as Greenland’s continental ice melting and also the increase in Agulhas Leakage. Therefore, this work aims to identify possible changes in the SAD pattern during the period after industrial revolution (1851-2010). The SAD is the first mode found through the Singular Value Decomposition (SVD) of SST and Mean Sea Level Pressure (MSLP). This analysis was performed at intervals of 30 and 10 years, in order to encompass the interannual and interdecadal cycles of the SAD oscillation, at the same time that it is possible to analyze possible changes in the SAD throughout the study period (1851-2010). Preliminary results show strong signs of changes in the SAD configuration, both in its oceanic and atmospheric components, which probably have impacts on the climate of the adjacent continents, which will be further studied later. The analysis performed with NOAA-CIRES 20th Century Reanalysis V2c indicate a clockwise rotation of the SST anomaly dipole pattern, while the associated MSLP anomalies show a northwestern shift over the study period.