Optimized Physical Tracer (OPT) reconstructions for past global ocean surface temperature, salinity and stable oxygen isotopes.

Global ocean surface Optimized Physical Tracer (OPT) reconstructions of temperature, salinity and stable oxygen isotopes (δ18O) at past times reconstructed from modern interior ocean observations. Modern co-located observations of temperature, salinity and δ18O from NASA-GISS (Schmidtet al., 1999) and CISE-LOCEAN (Reverdin et al., 2022) datasets were assimilated into a steady state observation-based circulation model, the Total Matrix Intercomparsion (TMI; Gebbie and Huybers., 2010, 2012).