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A reanalysis of
ocean climate

Introduction The goal of SODA is to reconstruct the historical physical (and eventually biogeochemical) history of the ocean. As its name implies, the Simple Ocean Data Assimilation ocean/sea ice reanalysis (SODA) uses a simple architecture based on community standard codes with resolution chosen to match available data and the scales of motion that are resolvable. Agreement with direct measurements (to within observational error estimates) as well as unbiased statistics are expected. While SODA remains a university-based research project, we want to be helpful. Our goal is to provide a reliable source of seasonal climate time-scale ocean reanalysis to complement the atmospheric reanalyses available elsewhere (NOAA/EMC, NASA/GMAO, and ECMWF, for example).

SODA Version 3 represents a major change from the previous SODA2. It now uses GFDL MOM5/SIS numerics at finer 1/4°x1/4°x50lev (28km at the Equator down to <10km at polar latitudes) resolution, similar to the ocean component of the GFDL CM2.5 coupled climate model, and includes an active sea ice component. The Optimal Interpolation filter has also been augmented (relative to previous releases) with bias correction to reduce bias in estimates of long term trends of variables such as heat content.

News 8 October, 2016 SODA3.3.1, forced by MERRA2 and spanning the 36-year period 1980-2015, is now available from this website along with a parallel simulation SODA3.3.0. We have also made available the 5-day and monthly fields remapped onto a uniform 1/2°x1/2° Mercator horizontal grid similar to SODA2, but with expanded vertical resolution along with variables on the native 1/4°x1/4°x50levx5dy tripolar grid and variables remapped onto an isopycnal grid.

A manuscript describing SODA3.3.1 will be put on this website in the next few weeks to provide users with a more detailed system description, some error analysis, and some simple statistics.

News 10 December, 2016 Production of SODA3.4.1, based on ERA-Int, is underway and should be available through this website in January, 2017. SODA3.4.1 encorporates some improvments as well such as the Bamber (2012) Greenland discharge estimates and improvements of the error covariances in the Arctic. For SODA3.3.1 we are adding some ancillary variables such as monthly dynamic height, corrected monthly sea level, and heat content.

Coming soon Next we expect to complete the ensemble of SODA3 reanalyses (1980-2015):

The spread in these will provide information regarding the uncertainty due to errors in surface forcing. A series of system upgrades and analysis studies will keep us busy for much of 2017. We will add the analysis of year 2016 for all of these by July 2017. By late-2017 we expect to return to the problem of a creating a reanalysis with quantified error estimates for the first half of the 20th century. Further forward: SODA4 will encorporate quasi-isopycnal dynamics, a new data assimilation scheme, and ocean biogeochemistry. The next major revision after that (provisionally SODA5) will be, or be part of, a fully coupled atmos/ocean/ice reanalysis.

For additional information send us email: Gena Chepurin and Jim Carton. If you don't get a response we've gotten distracted. Please keep trying!

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Acknowledgements SODA relies on extensive collaborations. In addition to the National Science Foundation Physical Oceanography Program we owe debts to: NOAA/GFDL, NOAA/NCEP, NOAA/NESDIS (especially the Laboratory for Satellite Altimetry and NCEI), NASA/GMAO, and the NASA MAP and Physical Oceanography programs. Many individuals have contributed to SODA including: Tim Boyer, Gil Compo, Dick Dee, Eric Hackert, Sirpa Hakkinen, Sasha Ignatov, Eugenia Kalnay, Syd Levitus, Matt Maltrud, Julie McClean, Laury Miller, Steve Penny, R. Raghunath, James Reagan, Tony Santorelli, Mike Steele, and most notably Ben Giese, Xianhe Cao, and Hank Seidel.

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