A reconstruction of the South Atlantic Meridional Overturning Circulation

  • 1 June 2017

Schematic of the MOC in the Atlantic Ocean with red indicating surface flows and blue indicating deep flows. Figure adapted from Perez et al. (2015)A study published in Geophysical Research Letters shows that observed sea surface temperature could help study variability of the South Atlantic Meridional Overturning Circulation and its impacts on climate and extreme weather. 

Researchers emphasized the importance of sustaining and combining ocean observing platforms with satellite observations. 

This study was supported by the CPO Climate Variability and Predictability program and the CPO Ocean Observing and Monitoring Division.

Read the paper:

Lopez, H., G. Goni, and S. Dong (2017), A reconstructed South Atlantic Meridional Overturning Circulation time series since 1870, Geophys. Res. Lett., 44, 3309–3318, doi:10.1002/2017GL073227.


This study reconstructs a century-long South Atlantic Meridional Overturning Circulation (SAMOC) index. The reconstruction is possible due to its covariability with sea surface temperature (SST). A singular value decomposition (SVD) method is applied to the correlation matrix of SST and SAMOC. The SVD is performed on the trained period (1993 to present) for which Expendable Bathythermographs and satellite altimetry observations are available. The joint modes obtained are used in the reconstruction of a monthly SAMOC time series from 1870 to present. The reconstructed index is highly correlated to the observational based SAMOC time series during the trained period and provides a long historical estimate. It is shown that the Interdecadal Pacific Oscillation (IPO) is the leading mode of SAMOC-SST covariability, explaining ~85% with the Atlantic Niño accounting for less than 10%. The reconstruction shows that SAMOC has recently shifted to an anomalous positive period, consistent with a recent positive shift of the IPO.




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