Overview

The National Science Foundation funded Simple Ocean Data Assimilation (SODA) project provides retrospectively integrated, spatially complete reconstructions of the global historical ocean climate. The project goal is to provide a uniform picture of the evolving global ocean/sea ice system at 5-dy time intervals beginning January, 1980. One example application is to provide the global context for process studies.

The method uses sparse physical oceanic/sea ice observations (including satellite SST and in situ temperature and salinity profiles) as constraints to guide the evolution of high-resolution numerical ocean models driven by specified atmospheric forcings. These constraints are imposed using sequential data assimilation. The version described here, known as SODA3 (more precisely SODA3.15.2), has ‘eddy-permitting’ ¼-deg horizontal resolution. For those users calculating closed heat or salt budgets a parallel simulation with no data assimilation, soda3.15.2.0, is also provided. The latest version of SODA, SODA4, has much finer ‘eddy-resolving’ 0.1-deg horizontal resolution which is required to resolve near-shore environments, shallow processes, or processes where flow instabilities dominate.

Dataset Metadata

Data Type Gridded reanalysis variables (NetCDF format)
Horizontal Resolution 0.25° x 0.25° grid (~28km at the equator)
Vertical Resolution 50 vertical ocean layers
Surface Forcing ECMWF ERA5
Assimilation Method Sequential analysis filter with multi-day updates & bias corrections
Key Variables Ocean Temperature, Salinity, Sea Level, Zonal/Meridional Velocities, Sea Ice Concentration

Download Gateway & File Formats

💡 File structures and naming conventions are detailed in the SODA3 Readme Document.

Select your requested dataset configuration below. You can copy bulk download command strings directly into terminal contexts or fetch files via targeted mirrors.

Direct Data Server Mirror

Access directories containing raw NetCDF data catalogs, index schemas, and multi-version libraries directly via HTTP OPeNDAP storage pathways.

Go to Data Server

5-Day Files

Original Grid: ~1/4°x1/4° displaced pole non-Mercator horizontal grid, 50 z* levels. (Ocean: 1.9Gb / Ice: 77Mb) 

wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_5dy_ocean_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/ORIGINAL/ocean/
wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_5dy_ice_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/ORIGINAL/ice/

Regridded Grid: Convenient 1/2°x1/2° Mercator grid, 50 z* levels. (Ocean: 286Mb / Ice: 15Mb) 

wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_5dy_ocean_reg_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/REGRIDED/ocean/
wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_5dy_ice_reg_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/REGRIDED/ice/

Monthly Files

Roughly 500 monthly average files on a regular 1/2°x1/2° Mercator grid at 50 z* vertical levels. (Ocean: 286Mb / Ice: 15Mb) 

wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_mn_ocean_reg_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/REGRIDED/ocean/
wget -r -l1 --no-parent --progress=bar -nd -A 'soda3.15.2_mn_ice_reg_*.nc' http://dsrs.atmos.umd.edu/DATA/soda3.15.2/REGRIDED/ice/

Direct Granular Links (By Year Archive):

1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

10-Day Files

Analysis Increments: Regular 1°x1° Mercator grid, upper 33 z* vertical levels. (25Mb each) 

wget -r -l1 --no-parent --progress=bar -nd -A.nc http://dsrs.atmos.umd.edu/DATA/soda3.15.2/SODA

Volume Transports: Original ~1/4°x1/4° displaced pole grid, 50 z* levels. (600Mb each) 

wget -r -l1 --no-parent --progress=bar -nd -A.nc http://dsrs.atmos.umd.edu/DATA/soda3.15.2/ORIGINAL/transport
⚠️ Grid Accuracy Note: Basin-integrated transport calculations (such as evaluating AMOC) must be conducted on the original grid to systematically avoid truncation errors found in standard remapped configurations.

Citations & Support

Users of SODA3 datasets are requested to acknowledge the SODA3 project and cite the primary methodology paper:

Carton, J.A., G.A. Chepurin, and L. Chen (2018), SODA3: a new ocean climate reanalysis, Journal of Climate, 31, 6967-6983. https://doi.org/10.1175/JCLI-D-18-0149.1

Contact Details

Principal Investigator: Dr. James A. Carton

Institution: Dept. of Atmospheric and Oceanic Science (AOSC), University of Maryland

Support Email: carton@umd.edu