ECMWF ORAS5

Area: Global

Period: 1979-2018

Data available: YES

Attention! The interpolated r1x1 degree data in both ORAS5 and ORAS5 backward extension are affected by a land-sea-mask issue during interpolation, and exhibit some anomalous points near coast/ocean bottom. By using the correct LSM, you can mask out all these anomalous points in r1x1 archived data as described in this Correction to ORA S5 r1x1 files manual (pdf, not barrier-free). The ORAS5 and ORAS5 backward extension data in native resolution are not affected.

Model: NEMO V3.4.1 coupled to LIM2 sea-ice model
Resolution: horizontal 1/4°x1/4° (~25 km in the tropics, and increases to 9 km in the Arctic), 75 vertical levels (level spacing increasing from 1 m at the surface to 200 m in the deep ocean)
Data assimilated: reprocessed SST from HadISST2 + OSTIA operational; reprocessed sea-ice concentration from OSTIA + OSTIA operation; reprocessed in-situ profiles from EN4 with XBT/MBT correction (Gouretski and Reseghetti, 2010) + GTS operational; AVISO reprocessed DT2014 SLA + NRT, with revised MDT; Global mean sea-level changes are constrained using AVISO DT2014 L4 MSLA + NRT
Ensemble: 5 ensemble members (opa0-4, with opa0 as the control member without perturbation), generated using perturbed initial conditions (see Zuo et al., 2018) + observation and forcing perturbations (see Zuo et al., 2017).
Assimilation method: 3DVar-FGAT as in ORAP5 + ensemble-based a-priori bias correction scheme + stability check for bias correction + updated observation QC + revised parametrizations
Forcing and relaxation used: ERA-40 (before 1979), ERA-Interim (1979-2015), ECMWF NWP (2015-present), bulk formula + revised wave forcing
Disclamer: ORAS5 was produced with ECMWF NWP forcing (from January 2015 onwards) and GTS opertional observations (from June 2015 onwards), therefore can be affected by incidents associated to the real-time operations.
Download Data: Get single files at ICDC | Download all files via wget | Table of Variables (pdf, not barrier-free)
Contact: Hao Zuo (hao.zuo (at) ecmwf.int), Magdalena Balmaseda, Magdalena.Balmaseda (at) ecmwf.int
References: Zuo, H., Balmaseda, M. A., Tietsche, S., Mogensen, K., and Mayer, M.: The ECMWF operational ensemble reanalysis–analysis system for ocean and sea ice: a description of the system and assessment, Ocean Sci., 15, 779–808, https://doi.org/10.5194/os-15-779-2019, 2019. (pdf, not barrier-free)
Zuo, H., Balmaseda, M. A., de Boisseson, E., Hirahara, S., Chrust, M., and De Rosnay, P., A generic ensemble generation scheme for data assimilation and ocean analysis. ECMWF Tech Memo., https://doi.org/10.21957/cub7mq0i4, 2017. (pdf, not barrier-free)
Information: https://www.ecmwf.int/en/research/climate-reanalysis/ocean-reanalysis