HUESS, V.'. JANDT-SCHEELKE, 5.2, KÄRNÄ, T.?, LAGEMAA, PD.“, LINDENTHAL, A.?, 
LORKOWSNI, 1.2, MALJUTENKO . 1."*, NORD, A.°, SCHWICHTENBERG, F.2, SHE, J.', TUOMI, L.?. 
Janish Meteorological Institute (DMI), Denmark - ?Bundesamt für Seeschifffahrt und Hydrographie (BSH), Germany - Finnish Meteorological 
ıstitute (FMI), Finland - “Tallinn University of Technology (TalTech), Estonia - Swedish Meteorological and Hydrological Institute (SMHI), Sweden 
The objective of the Copernicus Marine Service Baltic 
Monitoring and Forecasting Center (MFC) is to provide a 
state-of-the-art operational service with sea state, ocean 
physics and biogeochemical conditions of the Baltic Sea. 
This requires to operate up-to-date modelling systems 
with the best input and forcing data available. Starting 
Copernicus 1 contract in 2015, Baltic MFC products were 
based on different operational modelling systems provided 
by 5 institutes forming the Baltic MFC Consortium. Various 
ocean and biogeochemical model systems, as well as 
different forcing dataset were used. Our major achievement 
over the last six years, has been to successfully harmonize 
model systems and forcing dataset used in production. 
Also, model codes and forcing dataset had been updated. 
As a result, Baltic model products improved significantly to 
the benefits of Copernicus Marine Service users. 
During this six year period, the model development has 
been divided into two phases with respect to the ocean 
Model code system. During the first part (2015-2017) the 
main development was focused on improving the HIROMB 
8005 Model (HBM) ocean-ice system (Berg & Poulsen, 
2012). Then, an Intercomparison study between the HBM 
and the NEMO (Nucleus for European Modelling of the 
Icean; Madec et al., 2019) was performed. The outcome 
was a strategic decision in 2017: to phase out the HBM 
model system and move toward implementation of the 
more widely used community NEMO code as the Baltic 
MFC physical ocean model. 
During the second phase (2018-2021) all ocean model 
development focused on improving the implementation 
of the NEMO system for the Baltic Sea area. This was 
completed during year 2020, with the upgrade in the Baltic 
MFC product catalogue in 2020 where the NEMO model 
zubstituted the HBM as the ocean circulation model. The 
'mplementation and setup of this new system, called Nemo 
Nordic 2.0, is described in more detail in Kärnä et al., 2021. 
The best available dataset for the Baltic Sea area is 
expected to be used to force the models. This includes 
"nformation for river outflow and nutrient loadings, for 
which data from the latest updated E-HYPE hydrologicaı 
Nodel system (running at SMHI, Sweden) are employed. 
For the forecast product, atmospheric forcing data from 
the high resolution MetCoOp HARMONIE weather forecasts 
are used, with hourly frequency and 2.5 km resolution. For 
the multi-year products, data from the brand-new ERA5 
global reanalysis (issued by Copernicus Climate Change 
Service at ECMWF) are used. 
1. MAIN ACHIEVEMENTS FROM 2015 TO 2021 
1.1 The Blue and White ocean 
Major developments made in the HBM system during the 
rst years were on improving sea ice modelling, turbulence 
scheme and code modernization. For further details on the 
ABM achievements from 2015 to 2017 see description 
n Le Traon et al.,, (2017). The Baltic MFC consortium 
jecided in 2017 to move toward an implementation of 
"he NEMO system.. The NEMO system was introduced in 
‘he Baltic Service in the ocean reanalysis product. This 
setup was based on NEMO 3.6 and covered the Baltic 
3ea and North Sea area with a 2 nautical miles (> 3.7 km) 
1orizontal grid and 56 vertical levels. The domain has 
"wo open boundaries, one in the western English Channel 
and the other between Norway and Scotland. Efforts 
‘oward an operational forecast production started in 2018 
with a new grid of 1 nautical mile (> 1.85 km) horizontal 
resolution for the whole model area. During 2018 and 2019