This talk introduces the new 45-year long Simple Ocean Data Assimilation version 4 (SODA4) global (0.1°x0.1°x 75L) eddy-resolving ocean/sea ice reanalysis, which is the latest in the series of SODA reanalysis products. The basic software components used in SODA4 will be familiar to the Goddard audience, bearing close comparison to the ocean component of the S2S line of forecast models. I will provide a description of the analysis system, including discussion of numerical stability and what output variables are available. Comparisons to alternative products such as the UK Met Office EN4 temperature and salinity analysis as well as statistics of analysis increments shows that SODA4 has marginal bias and exhibits more regional variability, with less of an imprint of the sparse and inhomogeneous distribution of observations. This part of the talk will also include a comparison to independent mooring arrays. In the second half of the talk I'll discuss ocean variability and trends at high and low latitudes and discuss how the results are affected by the enhanced model resolution of SODA4.
