CoAuthors

Gustavo Goni (NOAA/AOML, United States); Shenfu Dong (NOAA/AOML, United States)

With the aid of altimetry derived sea surface height (SSH) and sea surface temperature (SST), we reconstruct a century-long South Atlantic Meridional Overturning Circulation (SAMOC) index and explores potential factors influencing its variability. The SAMOC reconstruction is possible due to its covariability with SSH and SST. A singular value decomposition (SVD) method is applied on the joint correlation matrix of SSH or SST and SAMOC. The SVD is performed on the trained period of 1993-2017 for which satellite altimetry observations are available. The joint modes obtained are used in the reconstruction of a monthly mean SAMOC timeseries from 1870 to 2017. The reconstructed index is highly correlated to the observed SAMOC timeseries during the trained period and provides a long historical estimate. It is shown that the Pacific Decadal Oscillation and the Atlantic Niño are the leading modes of SAMOC-SST-SSH covariability, explaining 75% and 15%, respectively. The reconstruction shows that SAMOC is currently in an anomalous positive (i.e., stronger than normal) phase.