SODA4: a mesoscale ocean/sea ice reanalysis 1980-2024

TL;DR

SODA4 is a comprehensive, mesoscale ocean and sea ice reanalysis covering 1980-2024, utilizing advanced data assimilation techniques to produce detailed and accurate global ocean state estimates.

Contribution

This paper introduces SODA4, a new mesoscale ocean/sea ice reanalysis that integrates modern numerics and observational data for improved accuracy over 45 years.

Findings

SODA4 shows marginal bias and regional variability in temperature and salinity.

Transport estimates across key sections align well with independent observations.

Compared to previous analyses, SODA4 exhibits less bias from sparse data.

Abstract

This paper describes the new Simple Ocean Data Assimilation version 4 (SODA4) global eddy-resolving ocean/sea ice reanalysis that spans the 45-year period 1980-2024. The reanalysis is constructed using GFDL MOM5/SIS1 numerics and ECMWF ERA5 forcings with surface and subsurface temperature and salinity observations as constraints within an optimal interpolation data assimilation algorithm. The method of construction and resulting output files are described. Comparison of the SODA4 temperature and salinity fields to observations and to the UK Met Office EN4 temperature and salinity analyses in the upper ocean shows SODA4 has marginal bias and exhibits more regional variability, with less of an imprint of the sparse and inhomogeneous distribution of observations. Comparison of transports across major ocean sections and passages are generally consistent with independent moored observations.