An Observations and Model Based Analysis of Meridional Transports in the South Atlantic

A three dimensional velocity field constructed from Argo observations and sea surface heights is used to estimate meridional volume and heat transports across 15S, 20S, 25S, 30S, and 35S for the years 2000 to 2014. Volume and heat transports form observations are compared with the estimates from three different ocean models (Hybrid Coordinate Ocean Model, Simple Ocean Data Assimilation and NCEP Global Data Assimilation Experiment) with data assimilation. Estimates from the observations are slightly higher than the models at 15S, 20S, 25S and, 30S. Model estimates are close to the observations at 35S, but the contributions of boundary currents and the interior to the overall transport deviate significantly from the observed structure. In addition, this structure varies greatly between the different models. Seasonality in the model estimates and the observations are analyzed and correlations between meridional volume and heat transports are assessed at different latitudes.