The Copernicus Global 1/12° Oceanic and Sea Ice GLORYS12 Reanalysis

Type Article
Date 2021-07
Language English
Author(s) Lellouche Jean-Michel1, Greiner Eric2, Bourdallé-Badie Romain1, Garric Gilles1, Melet Angélique1, Drévillon Marie1, Bricaud Clément1, Hamon Mathieu1, Le Galloudec Olivier1, Regnier Charly1, Candela Tony1, Testut Charles-Emmanuel1, Gasparin Florent1, Ruggiero Giovanni1, Benkiran Mounir1, Drillet Yann1, Le Traon Pierre-Yves1, 3
Affiliation(s) 1 : Mercator Ocean International, Ramonville Saint Agne, France
2 : Collecte Localisation Satellites, Ramonville Saint Agne, France
3 : Ifremer, Plouzané, France
Source Frontiers In Earth Science (2296-6463) (Frontiers Media), 2021-07 , Vol. 9 , P. 698876 (27p.)
DOI 10.3389/feart.2021.698876
WOS© Times Cited 32
Keyword(s) ocean and sea ice reanalysis, data assimilation, high-resolution model, ocean variability, operational oceanography, Copernicus marine service
Abstract

GLORYS12 is a global eddy-resolving physical ocean and sea ice reanalysis at 1/12° horizontal resolution covering the 1993-present altimetry period, designed and implemented in the framework of the Copernicus Marine Environment Monitoring Service (CMEMS). The model component is the NEMO platform driven at the surface by atmospheric conditions from the ECMWF ERA-Interim reanalysis. Ocean observations are assimilated by means of a reduced-order Kalman filter. Along track altimeter sea level anomaly, satellite sea surface temperature and sea ice concentration, as well as in situ temperature and salinity vertical profiles are jointly assimilated. A 3D-VAR scheme provides an additional correction for the slowly-evolving large-scale biases in temperature and salinity. The performance of the reanalysis shows a clear dependency on the timedependent in situ observation system. The general assessment of GLORYS12 highlights a level of performance at the state-of-the-art and the capacity of the system to capture the main expected climatic interannual variability signals for ocean and sea ice, the general circulation and the inter-basins exchanges. In terms of trends, GLORYS12 shows a higher than observed warming trend together with a slightly lower than observed global mean sea level rise. Comparisons made with an experiment carried out on the same platform without assimilation show the benefit of data assimilation in controlling water mass properties and sea ice cover and their low frequency variability. Moreover, GLORYS12 represents particularly well the small-scale variability of surface dynamics and compares well with independent (non-assimilated) data. Comparisons made with a twin experiment carried out at 1/4° resolution allows characterizing and quantifying the strengthened contribution of the 1/12° resolution onto the downscaled dynamics. GLORYS12 provides a reliable physical ocean state for climate variability and supports applications such as seasonal forecasts. In addition, this reanalysis has strong assets to serve regional applications and provide relevant physical conditions for applications such as marine biogeochemistry. In the near future, GLORYS12 will be maintained to be as close as possible to real time and could therefore provide relevant and continuous reference past ocean states for many operational applications.

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Lellouche Jean-Michel, Greiner Eric, Bourdallé-Badie Romain, Garric Gilles, Melet Angélique, Drévillon Marie, Bricaud Clément, Hamon Mathieu, Le Galloudec Olivier, Regnier Charly, Candela Tony, Testut Charles-Emmanuel, Gasparin Florent, Ruggiero Giovanni, Benkiran Mounir, Drillet Yann, Le Traon Pierre-Yves (2021). The Copernicus Global 1/12° Oceanic and Sea Ice GLORYS12 Reanalysis. Frontiers In Earth Science, 9, 698876 (27p.). Publisher's official version : https://doi.org/10.3389/feart.2021.698876 , Open Access version : https://archimer.ifremer.fr/doc/00706/81775/