Overview of current ocean reanalyses

Submitted by Cathy.Smith@noaa.gov on Thu, 10/07/2010 - 14:05

Individual Descriptions


Model: MOM4.0
Resolution: Vertical 40 levels and 0.5 deg in the zonal direction. In the meridional direction it is 0.25 between 10S-10N and 0.5 poleward 30
Data Range: 2004-latest (almost real time)
Data assimilated: Insitu temperature and salinity profiles from moorings (TAO/TRITON/PIRATA/RAMA and national buoy data), XBT/XCTDs, and Argo. Reynolds SST
Assimilation Method: 3D-VAR for T&S profile assimilation + Nudging for relaxing model SST 
Forcing: Radiation and freshwater fluxes from NCEP-R2 till 2009 and from 2010 they are from NCMRWF. Momentum fluxes are from QuikScat till October, 2009 and DASCAT from November 2009-2012, and NCMRWF from 2013 onwards.
Download Data at: http://las.incois.gov.in (ocean analysis folder)
Contact: ssiva@incois.gov.in
Information: http://www.incois.gov.in/portal/GODAS
Sivareddy, S., 2015, A study on global ocean analysis from an ocean data assimilation system and its sensitivity to observations and forcing fields. Ph.D. thesis, Andhra University
Ravichandran, M., D. Behringer, S. Sivareddy, M. Girishkumar, N. Chacko, and R. Harikumar, 2013: Evaluation of the global ocean data assimilation system at INCOIS: The tropical Indian Ocean. Ocean Modelling, 69, 123-135.


Model: MOM4 + Chen hybrid mixed layer
Resolution: Vertical 47 levels
Date Range: Earliest experiment starts 1992 and latest ends 2008
Data assimilated: Satellite, SST, SSH, Argo, XBT, TAO
Assimilation method: Simplified ensemble Kalman Filter
Forcing and relaxation used: No global constraints
Download Data:
Information: www.cmar.csiro.au/staff/oke/BRAN.htm


Model: NEMO V3.2 + LIM2
Resolution: Horizontal 1/4°x1/4° (ORCA025 tripolar grid) with 50 vertical z levels
Date Range: 1980-2015
Data assimilated: Temperature and Salinity profiles from EN3v2a (XBT, CTD, Argo, Mooring). Altimeter sea level anomalies from AVISO (Delayed time along-track data). NOAA 1/4 Daily SST analyses (OIv2). "NASA Team" Sea Ice Concentration (provided by NSIDC).
Assimilation method: Multivariate 3DVAR (for insitu and SLA) + Large-Scale Bias correction + Nudging (SST, SIC)
Forcing and relaxation used: ERA-Interim through CORE bulk formulas.
Download Data: C-GLORS Data Dissemination or CMEMS portal (Link)
Contact: Andrea Storto, Andrea.Storto (at) cmcc.it
References: C-GLORS Bibliography
Information: C-GLORS Website

CMCC CHOR (Historical Reanalyses)

Model: NEMO V3.4 + LIM2
Resolution: Horizontal 1/2°x1/2° (ORCA05 tripolar grid) with 75 vertical z levels
Date Range: 1900-2010
Data assimilated: Temperature and Salinity profiles from EN4 (XBT, CTD, Argo, Mooring). SST from ICOADS (CHOR_AS) or HadISST analyses (CHOR_RL).
Assimilation method: Multivariate 3DVAR (for insitu)
Forcing and relaxation used: 20CRv2 (with high-latitude corrections) through CORE bulk formulas.
Download Data: CHOR Data Dissemination
Contact: Chunxue Yang, c.yang (at) isac.cnr.it
References: CHOR Bibliography
Information: CHOR Website



Model: GODAS w/MOM4
Resolution: Vertical  40 levels. Horizontal .25 near the equator; 0.5 beyond the tropics
Date Range: 1979-near present
Data assimilated: 
Assimilation method: 
Forcing and relaxation used: 

ECMWF ORAP5 (1979-2013).

Model: NEMO V3.4.1
Resolution: Horizontal 1/4°x1/4°, 75 vertical levels, about 1m level thickness in upper 200 m.
Date Range: 1979-2013
Data assimilated: Temperature and Salinity profiles from the EN3 v2a database with XBT bias correction, including XBT, CTD, Argo, Mooring, and from realtime GTS thereafter.  Along track altimeter sea level anomalies and global trends from AVISO. SST and sea-ice are from the ERA-40 archive (before Auguest 1981), OSTIA analysis (1985-2007) and operational real-time OSTIA (2009 to 2013). For the period when OSTIA is not available the 1/4 degree daily NOAA OIv2d analysis is used.
Assimilation method: NEMOVAR in its 3D-Var FGAT mode. The assimilation window is 5 days. A bias correction scheme is used to correct the model/forcing errors.
Forcing and relaxation used: All the surface forcing fields are from ECMWF ERA-Interim atmospheric reanalysis product, with addititional wave fields.
Contact: Hao Zuo,  hao.zuo@ecmwf.int
References: Zuo, H., Balmaseda, M. A. and Mogensen, K., 2015. The new eddy-permitting ORAP5 ocean reanalysis: description, evaluation and uncertainties in climate signals. Climate Dynamics, 10.1007/s00382-015-2675-1
Tietsche, S., Balmaseda, M.A., Zuo, H. and Mogensen, K., 2015. Arctic sea ice in the global eddy-permitting ocean reanalysis ORAP5. Climate Dynamics, 10.1007/s00382-015-2673-3
Zuo, H., Balmaseda, M.A., and Mogensen, K., 2015. The ECMWF-MyOcean2 eddy-permitting ocean and sea-ice reanalysis ORAP5. Part 1: Implementation. ECMWF Tech Memo (736)

ECMWF ORAS4 (1958-present). Vintage 2010

Model: NEMO V3.0
Resolution: Horizontal 1°x1° with equatorial refinement (0.3). 42 vertical levels, about 10m level thickness in upper 200 m.
Date Range: 1958-near present
Data assimilated: Temperature and Salinity profiles from the from the EN3 v2a XBT bias corrected database (1958-2009), including XBT, CTD, Argo, Mooring, and from realtime GTS thereafter.  Along track altimeter sea level anomalies and global trends from AVISO. SST and sea-ice are from the ERA-40 archive prior to November 1981, from the NCEP OI v2 weekly product (1981 until December 2009) and , and from OSTIA analysis from January 2010 onwards.The SST and sea-ice information is used to constrain the upper level ocean temperature via a newtonian relaxation scheme.
Assimilation method: NEMOVAR in its 3D-var FGAT mode. The assimilation window is 10 days. A bias correction scheme is used to correct the model/forcing errors.
Forcing and relaxation used: Daily surface fluxes of heat, momentum and fresh water are used. Prior to 1989, the surface fluxes are from the ERA-40 atmospheric reanalysis. From the period 1989-2009, the surface fluxes are from ERA-Interim reanalysis. From 2010 onwards, when ORAS4 started operational running, daily surface fluxes were derived from the operational ECMWF atmospheric analysis.
Download Data: Hamburg Ocean Server OPeNDAP at ICDC, FTP at ICDC, View in LAS at ICDC
Contact: Magdalena Balmaseda, Magdalena.Balmaseda (at) ecmwf.int
References: Balmaseda M.A,. K. Mogensen, A. Weaver, 2013: Evaluation of the ECMWF Ocean Reanalysis ORAS4. Q. J. Roy. Met. Soc. In press
Mogensen, K., M. Alonso Balmaseda, A. Weaver, 2012: The NEMOVAR ocean data assimilation system as implemented in the ECMWF ocean analysis for System4. ECMWF Thechnical Memorandum 668. 59 pages.
Information: http://www.ecmwf.int/en/research/climate-reanalysis/ocean-reanalysis

ECMWF ORAS3 (1959-2011). Vintage 2006. 

Model: HOPE
Resolution: Horizontal 1°x1° with equatorial refinement (0.3). 29 vertical levels, about 10m-15m level thickness in upper 200 m.
Date Range:1959-2011
Data assimilated: Temperature and Salinity profiles from the EN3 database (1959-2007), including XBT, CTD, Argo, Mooring, and from realtime GTS thereafter. Altimeter sea level anomalies maps and trends from AVISO, plus XBT corrections (Wijffels et al 2008). Operational GTS data thereafter.
Assimilation method: Multivariate OI + Bias correction
Forcing and relaxation used: ER40 (precip corrected) daily fluxes from 1959-2002. ECMWF operational NWP fluxes therefater. SST as in ERA-40 until 1982 and the weekly NOAA oiv2 1x1 from 1982 onwards.
Download Data: order at www.ecmwf.int
Contact: Magdalena Balmaseda, Magdalena.Balmaseda (at) ecmwf.int
References: ECMWF - Ocean Analysis; ECMWF - ENSEMBLES RT1 Home
Information: http://www.ecmwf.int/en/research/climate-reanalysis/ocean-reanalysis


Model: MITgcm and MOM4
Resolution: Horizontal 1°x1° Vertical 50 levels, 10 in top 100m
Date Range: 1993-present
Data assimilated: Temperature temperature profiles from Argo and XBT, CTD Altimetry
Assimilation method: Kalman filter and RTS smoother
Forcing and relaxation used:
Download Data:
Information: ECCO Datapage


Model: MITgcm
Resolution: Horizontal 1°x1° Vertical 23 levels
Data assimilated: CTD, MBT/XBT, Argo, TOGA/TAO,T/P-ERS- ENVISAT,Jason, AMSR/E/TMI SST, Quicksact, mean surface drifter velocity, GRACE SSH, Levitus (1994) NCEP RA1
Assimilation method: 4D-VAR (adjoint) method controlling the T/S initial conditions and ten daily air-sea fluxes (heat, fresh water, and momentum fluxes)
Forcing and relaxation used: Daily forcing (twice a day wind) for first guess momentum, net heat , shortwave heat and fresh water fluxes from NCEP-1. No relaxation used.
Download Data: OpenDAP from ICDC, ftp from ICDC, View with LAS from ICDC
Contact: Armin Köhl, armin.koehl (at) zmaw.de
References: Köhl A. and D. Stammer (2008), Variability of the Meridional Overturning in the North Atlantic from the 50 years GECCO State Estimation, J. Phys. Oceanogr., 38, 1913-1930.
Information: ifm.zmaw.de


Model: GFDL's Ensemble Coupled Data Assimilation (ECDA) system
Resolution: Global Tripolar grid (360 by 200), 50 z-levels with partial steps
Date Range: 1961-2012
Data assimilated: NCEP reanalysis winds, air temperature, and surface pressure (NCEP/NCAR: 1960-1978, NCEP/DOE: 1979-ongoing). HadSST(1960-1980), OISST(1981-ongoing), WOD09(XBT, CTD, OSD, MBT, MRB: 1960-2008), Pseudo salinity(1993-2002), GTSPP(XBT and MRB:2009-ongoing), Argo (2000-ongoing)
Assimilation method: Ensemble Kalman Filter
Forcing and relaxation used:  Fully coupled based on CM2.1
Download Data: http://www.gfdl.noaa.gov/ocean-data-assimilation
Contact: Gabriel.A.Vecchi [at] noaa.gov, Shaoqing.Zhang [at] noaa.gov, Xiaosong.Yang [at] noaa.gov
- Zhang S., M. J. Harrison, A. Rosati, and A. T. Wittenberg, 2007: System design and evaluation of coupled ensemble data assimilation for global oceanic climate studies. Mon. Weather Rev., 135(10), doi:10.1175/MWR3466.1.
- Chang Y.-S., S. Zhang, A. Rosati, T. L. Delworth, and W. F. Stern, 2012: An assessment of oceanic variability for 1960-2010 from the GFDL ensemble coupled data assimilation. Clim. Dyn., online-first, doi:10.1007/s00382-012-1412-2.


Realization: Mercator Océan / CNRS / Coriolis
Numerical Model: NEMO 3.1
Model configuration: ORCA025 (Global, 1/4° Mercator grid, 75 vertical z-levels, 1m top level, 200m bottom level).
Date Range: 1992-2009
Period and atmospheric forcing: 1992-2009, ECMWF ERA-Interim reanalysis
Data assimilated: CORA3v1 T&S profiles delayed time data base (CORIOLIS GDAC), REYNOLDS 0.25° AVHRR-only SST, delayed time AVISO along track SLA
Assimilation method:  Reduced order Kalman filter based on SEEK formulation
Forcing and relaxation used: ERA-Interim reanalysis with satellite based corrections for SW and LW, no relaxation
Download Data: http://www.myocean.eu , products [AT] mercator-ocean.fr
Contact: Bernard Barnier (bernard.barnier[AT]legi.grenoble-inp.fr), Nicolas Ferry (nferry [AT] mercator-ocean.fr), products [AT] mercator-ocean.fr
References:  N. Ferry, L. Parent, G.Garric, B. Barnier, N. C. Jourdain and the Mercator Ocean team, 2010: Mercator Global Eddy Permitting Ocean Reanalysis GLORYS1V1: Description and Results, Mercator Ocean Quarterly Newsletter, #36 – January 2010, 15-27. http://www.mercator-ocean.fr/documents/lettre/lettre_36_en.pdf
N. Ferry, L. Parent, G. Garric, C. Bricaud, C-E Testut, O. Le Galloudec, J-M Lellouche, M. Drevillon, E. Greiner, B. Barnier
, J-M Molines, N. C. Jourdain, S. Guinehut, C. Cabanes, L. Zawadzki, 2012:  GLORYS2V1 global ocean reanalysis of the altimet
ric era (1992-2009) at meso scale. Mercator Quarterly Newsletter 44, January 2012, 29-39. available at http://www.mercator-o
Barnier B. and co-authors, 2006: Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution, Ocean Dynamics, 56(5-6):543-567. http://www.springerlink.com/content/w8327463321564n3/


Resolution: 1/2° Ocean, 1° Atmosphere
Date Range: 1980-present
Data assimilated: Argo, XBT, CTD, TAO, PIRATA, RAMA, Reynolds SST, SLA (T/P, Jason 1-2)
Assimilation method: Ensemble OI
Forcing and relaxation used: Dynamical AGCM constrained to MERRA
Download Data: http://gmao.gsfc.nasa.gov/research/ocean/DATA_PORTAL/index.php
Contact: guillaume.vernieres-1@nasa.gov
Information: gmao.gsfc.nasa.gov


Model: MOMv3
Resolution: Horizontal 1°x1° (1/3° meridional at the tropics) Vertical 40 levels, 10m res.in top 200m
Date Range: 1979-present
Data assimilated: Temperature XBTs and TAO/Triton/PIRATA, Argo Salinity synthetic based on T(z) and local TS-correlation Altimetry Jason-1 altimery Forcing Momentum, shortwave, longwave, sensible heat, latent heat, P-E fluxes from the NCEP Reanalysis 2 Relaxation surface temperature to Reynolds' weekly SST OI, surface salinity to monthly Levitus climatological SSS
Assimilation method:
Forcing and relaxation used:
Download Data:
Information: http://www.cpc.ncep.noaa.gov/products/GODAS/
Data: NCAR


Model: POP2.x
Resolution: Horizontal 0.25° on average (0.25°x0.4° tropics) Vertical 40 levels, 10m top layer
Data assimilated: WOD09 standard level T&S, ICOADS 2.5 SST
Assimilation method:
Forcing and relaxation used: 20CRv2 surface wind stress and variables for bulk formulae
Download Data: OpenDAP from soda.tamu.edu
Contact: Howard Seidel (hank @ tamu.edu)
References: J.A. Carton and B.S. Giese, 2008: A reanalysis of ocean climate using Simple Ocean Data
Assimilation (SODA), Monthly Weather Review, 136, 2999-3017. J. A. Carton, G. Chepurin, X. Cao, and B. S. Giese, 2000: A Simple Ocean Data Assimilation analysis of the global upper ocean 1950-95. Part I: Methodology, Journal of Physical Oceanography, 30, 311-326.
Information: soda.tamu.edu



University of Reading UR025.3 (1989 – 2010)


Model: NEMO coupled ice-ocean model v2.3

Configuration: ORCA025_LIM2 (1/4o by 46 vertical levels)

Data assimilated:  UR025.3 assimilates in situ temperature and salinity observations that were obtained from the UK Met Office quality controlled ENACT/ENSEMBLES (EN3_v2a) dataset available from (http://www.metoffice.gov.uk/hadobs/en3/). A detailed description of the data set including the quality control processing is presented in Ingleby and Huddleston (2007).

Assimilation method: Temperature profiles (T) are assimilated along with a salinity balancing increment following the method of Troccoli and Haines, 1999). Salinity profiles (S) are then assimilated along isotherms (i.e., S(T)) up to latitudes of around 50oN/S, using the methodology described by Haines et al. (2006). At higher latitudes salinity is assimilated in a univariate way on z levels. Model – data differences (innovations) are evaluated at the closest model time step, and assimilation increments are calculated every 5 days. Increments are then introduced into the model evenly over the following day (Incremental Analysis Updating, Bloom et al., 1996). Smith and Haines (2009) give more details of the assimilation methodology.

Surface Forcing: Surface atmospheric forcing for UR025.3 is obtained from ECMWF ERA-Interim atmospheric reanalysis (Simmons et. al., 2007; Dee and Uppala, 2009; Dee et al., 2011). The ERA-Interim reanalysis provides 10-m wind, 2-m air humidity and 2-m air temperature to compute 6-hourly turbulent air/sea and air/sea-ice fluxes during model integration, using the bulk formula proposed by Large and Yeager (2004, 2009). Downwelling short and long wave radiative fluxes and precipitation are also provided by ERA-Interim. The river runoff is  Dai and Trenberth (2002). To prevent drift in the density distributions, a sea surface salinity relaxation to the WOA05 climatology, Boyer et al (2006), is applied with a timescale of 180 days for the top 10 m at the ice-free surface, decreasing to 36 days under ice.
Download Data: http://www.myocean.eu
Contact: Maria Valdivieso, Department of Meteorology, University of Reading, UK (m.valdiviesodacosta@reading.ac.uk)

References:  M. Valdivieso and K. Haines, 2011: Scientific Validation Report (ScVR) for v1 Reprocessed Analysis and Reanalysis. GMES Marine Core Services Technical Report WP04-GLO-U-Reading_v1, 28 pp, March 2011

K. Haines, M. Valdivieso, H. Zuo and V. N. Stepanov, 2012: Transports and Budgets in a 1/4o global ocean reanalysis 1989–2010. Ocean Sci. Discuss., 9, 261 – 290, 2012


University of Reading UR025.4 (1989 – 2010)

Model: NEMO coupled ice-ocean model v3.2

Configuration: ORCA025_LIM2 (1/4o by 75 vertical levels)
Date Range: 1989-2010

Data assimilated:  UR025.4 assimilates in situ (ICOADS) and satellite (AVHRR + AATSR) SSTs, altimeter SLA from AVISO CLS (http://www.aviso.oceanobs.com/en/), in situ temperature and salinity profile observations obtained from the UK Met Office ENACT/ENSEMBLE EN3_v2a_NoCWT_LevitusXBTMBT_Corr data set (http://www.metoffice.gov.uk/hadobs/en3/) which includes bias corrections for XBT and MDT data, and satellite-based sea ice concentrations from the EUMETSAT Ocean Sea Ice satellite Application Facility (OSI-SAF, http://osisaf.met.no).
Assimilation method: The data assimilation methodology is similar to what is currently employed in the UK Met Office operational FOAM – NEMO system (Storkey et al., 2010).
It is an Optimal Interpolation (OI)– type scheme (Lorenc et al., 1991) with assimilation increments calculated using a first-guess-at-appropriate-time (FGAT) scheme every 5 days (73 assimilation cycles per year) and introduced evenly over the period in an incremental analysis update (IAU, [Bloom et al. 1996]) step.
Surface Forcing: The model is forced with the ECMWF ERA-Interim atmospheric reanalysis (10 m wind, 2 m air humidity and temperature, downwelling short and long wave radiation, precipitation and snow) with bulk fluxes calculated as Large and Yeager (2004, 2009). The monthly climatological river runoff of Dai and Trenberth (2002) is applied along the land mask. There is no sea surface salinity restoring in UR025.4. 
Download Data: http://www.myocean.eu
Contact: Maria Valdivieso, Department of Meteorology, University of Reading, UK (m.valdiviesodacosta@reading.ac.uk)
References:  M. Valdivieso, K. Haines and H. Zuo, 2012: MyOcean Scientific Validation Report (ScVR) for v2.1 Reprocessed Analysis and Reanalysis. GMES Marine Core Services Technical Report WP04-GLO-U-Reading_v2.1, 61 pp, February 2012.



Ocean Synthesis/Reanalysis Directory at U. of Hamburg contains additional data sets and access links.


nadia pinardi (not verified)

Fri, 08/31/2012 - 13:35

Dear Sirs, we have available a high resolution ocean re-analysis for the period 1985-2007 at 1/16 degree resolution and we make it availabel through ftp to many users. The reference publication is: Adani, Mario, Srdjan Dobricic, Nadia Pinardi, 2011: Quality Assessment of a 1985–2007 Mediterranean Sea Reanalysis. J. Atmos. Oceanic Technol., 28, 569–589., doi:10.1175/2010JTECHO798.1 We will be interested to put the information about our re-analysis on this web site, is it possible? Best regards Nadia

Dear Nadia,

Adding your reanalysis dataset would be great. Please login and modify the page so that your information is included as you would like to see it. Reanalyses.org is a user-driven site. Each reanalysis group has added the information about their own dataset, or individual users have added information as they found datasets.
Please request an account at
and then edit the page to include your dataset.

Please feel free to ask questions or post them to the Help area once you are logged in.

best wishes,
gil compo
for Reanalyses.org

Naresh (not verified)

Fri, 07/26/2013 - 11:43

I need SODA reanalysis latest version for my research. I was unable to download from here. Is there any way that I can get this data for free ? I need, zonal, meridional, vertical winds and temperature data.

Leo (not verified)

Fri, 08/30/2013 - 21:51

I need daily reanalysis data, could you give some information about time resolution of the datasets?


Sat, 08/31/2013 - 18:00

In reply to by Leo (not verified)

Leo, Please include what variables you need and over what time range, i.e., daily wind stress from 1979 onwards. best wishes, gil compo U. of Colorado/CIRES & NOAA Earth System Research Laboratory/Physical Sciences Division

golfmi (not verified)

Mon, 12/29/2014 - 09:32

Which dataset is regarded the best? I will be interested in high resolution, only surface/high layer with particular focus on how the current works around the points of the continents. Thank you

Dimitris Menemenlis (not verified)

Mon, 12/29/2014 - 22:29

Depends what your intended use is? Are you interested in a solution that is as close as possible to the data, a solution that is property conserving and does not contain discontinuities, or a solution that is as physically realistic as possible?

Steeven Paul (not verified)

Wed, 05/04/2016 - 07:03

I want dialy data of ocean reanalysis for the indian ocean region. I far as i know GODAS providing pentad data and ECCO2 provides 3-day averages, please let me know where can i get the daily ocean reanalysis data. Thank You.

Dear Steeven, From Suru Saha of NCEP: The CFSR hourly hi-res 3D ocean data can be downloaded from NCEI from Jan 1979-March 2011. Example: For Jan 1 1979 http://nomads.ncdc.noaa.gov/modeldata/cmd_ocnh/1979/197901/19790101/ After that, the CFSR became operational (CFSv2) from April 2011 - present. Example: For April 1, 2011 http://nomads.ncdc.noaa.gov/modeldata/cfsv2_analysis_ocnh/2011/201104/20110401/ Please let me know if you need more information. Thanks Suru Suranjana Saha, Ph.D. Physical Scientist Environmental Modeling Center/NCEP/NWS/NOAA College Park, MD, USA

Hi Mr. Paul, I don't know of any daily ocean reanalyses specifically, but if you look here: http://icdc.zmaw.de/projekte/easy-init/easy-init-ocean.html there are 20-30 listed. This information is a provided as part of the Copernicus Marine Environment Monitoring Service. Best of Luck, Steve

Anonymous (not verified)

Fri, 05/27/2016 - 03:59

I am looking for mixed layer changes (and possibly nitrates) over summer for Laptev, East Siberian and Chukchi seas (Chukchi being the most important). I would like data for 2012 until present if possible. Would this be possible? Thanks

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