MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
A GLOBAL 1/12° physical reanalysis (GLORYS12v1) is 
available since April 2018 and provides daily products 
starting in 1993 available on 1/12° regular grid. The 
multi system Global Reanalysis Ensemble Product 
(GREP) at lower resolution (1/4°) is covering the same 
period and is available since 2019. In 2020 all temporal 
extension of reanalysis timeseries were produced using 
the ERA5 atmospheric reanalysis instead of ERAinterim, 
A GLOBAL 1/5° wave reanalysis (WAVERYSv1); based 
an the MFWAM model, assimilating reprocessed 
SWH observations and directional wave spectra from 
Sentinel-1; and forced by ECMWF ERAb5 reanalyses. 
has been produced,. Daily products starting in 1993 are 
available on 1/4° regular grid since December 2019, 
A GLOBAL 1/4° biogeochemical reanalysis (BIORYS4v4) 
is based on the PISCES model without DAdata 
assimilation and forced by physical simulation without 
data assimilationDA. Daily products starting in 1993 
are available on 1/4° regular grid since July 2019 and 
axtension of timeseries are provided using physical 
simulation forced by ERA5 atmospheric forcing since 
July 2020, 
A GLOBAL 1/12° micronekton reanalysis (MICRORYSv2) 
is based on the Seapodym model without DA and is 
forced by GLORYS12v1 and Net Primary Production 
merged between satellite observation and BIORYS4v4. 
Weekly products starting in 1998 are available on 1/12° 
regular grid since May 2021. A previous version at lower 
resolution (1/4°) was developed and disseminated in 
2019 
3. POST 2021 PERSPECTIVES 
3.1 Update of the global reanalyses, 
analysis and forecasting physical systems 
Next versions of the global forecasting (GLO12v4) and 
reanalysis systems (GLORYS12v2) are under development, 
‚n order to improve, among others:, the representation of 
mesoscale activity, the mass/steric distribution (loss of 
mass and too much steric in GLO12v3 and GLORYS12v1), 
and equatorial dynamics which directly impact the 
biogeochemistry. To achieve these ambitious goals, focus iwas 
set toon developments in the ocean model, reanalyses and 
data assimilation method. Some steps in the developments 
for these versions of the systems are tested, other are 
oNgoing. 
About models, we have implemented version 3.6 of NEMO 
and version 3 of LIM sea ice model are implemented. 
Consequently, the time-splitting mode is operated enabling 
rapid barotropic waves in the system, high resolution spatia: 
and temporal atmospheric forcing. 
About reanalyses, we have implemented the use of the 
interannual discharge of 13 major rivers based on GloFas 
data and CMEMS BRONCO service evolution project are used. 
Parametrization for ocean/atmosphere interaction (Renault 
et al., 2019) is updated as well as light penetration using a 
5-bands formulation and vertical diffusion using a second 
order k-epsilon scheme (Reffray et al, 2015). 
About Regarding data assimilation, a 4D analysis with a 
new Mean Dynamic topography is now exploited and an 
updated data base of error covariances (computed from the 
5LORYS12v1 reanalysis) is leveraged. The temperature and 
salinity large scale bias correction method based on a 3Dvar 
analysis has been optimized. For assimilated observations, the 
main update concerned the SST. In the near real time system 
‘GLO12v4), now the L3 Odyssea SST product is assimilated, and, 
in the reanalysis (GLORYS12V2), now the L4 OSTIA SST product 
is assimilated. A new Mean Dynamic Topography is also used 
to assimilate Sea Level Anomaly in the system. An ocean wave 
zoupled approach as described in Law Chune and Aouf (2018) 
will be also investigated for reanalysis and forecast systems. 
Before launching the target system at 1/12° of resolution 
in 2022, several unitary tests based on development listec 
above have been performed in a “twin” global system at %°. 
Improvements have been quantified and will be documented 
with the new version of CMEMS products including impact on 
the biogeochemistry system. 
A significant development started during Copernicus 
| period is the improvement of atmospheric forcings used 
to force ocean real-time and reanalysis systems (based 
an meteorological forecasts and reanalysis produced by 
ECMWF). However, this approach has two main shortcomings. 
First, there is an inconsistency between atmospheric forcing 
and ocean surface conditions which can deteriorate ocean 
forecasts. Then, ocean feedback on atmospheric forcings 
ıSs currently neglected, while it is now clearly established 
that ocean surface mesoscale features (such as eddies anc 
fronts) significantly influence the atmosphere evolution. 
To avold such issues, coupled ocean-atmosphere models 
represent a satisfying scientific solution despite having some 
ılmitations. For instance, the prohibitive numerical cost at 
high resolutions, and initialization issues related to the lack of 
zoupled assimilation systems. 
Consequently, GLO MFC decided to develop an Innovative 
solution consisting in the coupling of the ocean model to a 
reduced-complexity atmospheric boundary layer model 
named ABL1D (Lemarie et al, 2021). This model resolves 
anly the necessary atmospheric processes to represent 
air-sea interactions accurately, while being driven by the 
meteorological forecast or reanalysis from ECMWF. Such a 
strategy offers significant benefits compared to forced ocean 
models and coupled models: