MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
Atthe end of 2020, a number of 60 users have downloaded 
BS-MFC products with around 3 TB of downloaded data 
and about 300k downloads from the catalogue. The area 
of benefits includes business and private companies 
(45%), academia (20%) and public sector (32%) according 
to 2019 internal reporting. Applications that use BS-MFC 
products are mainly dedicated to Commercial sector and in 
particular the Blue Economy. Such encouraging statistics 
are also supported by a very robust service, that ensures 
a minimum number of incidents or failures thanks to a 
very strict service monitoring and support to Production 
Units. Timeliness of BS-MFC products is around 99.9%, 
with some expected degradation - but always above 95% 
- at the occurrence of a new release. In 2020, the number 
af incidents has dramatically decreased (from about 40 in 
20197 up to 15) thanks to improved operational chains and 
reliable interfaces PU-DU. 
1.2 BS-MFC Physics 
The nominal product for BS-PHY NRT [1] provides analysis 
and 10-days forecast every day, as hourly and daily means 
with nominal start of the forecast at 00:00UTC for the 
following list of variables: 
- 3D temperature, 
salinity and currents, 
D sea surface height, 
- mixed layer depth and bottom temperature. 
The BS-PHY NRT system (EAS3 version) is based on NEMO 
3.4 hydrodynamical model, implemented on a spatial 
grid of 3 km resolution and 31 z-levels, online coupled 
to OceanVar [2.3] for the assimilation of near real time 
observations (in situ temperature and salinity profiles, sea 
level anomaly along track and sea surface temperature, 
provided by corresponding CMEMS TACs). It is forced by 
ECMWF IFS analysis and forecast atmospheric fields at 12.5 
km horizontal resolution and 3-6 h temporal frequency. It 
ımplements a closed boundary condition at the Bosporus 
Strait. An operational dashboard for monitoring analysis 
accuracy Is provided by a regional website developed by 
CMCC that publishes daily bulletin for BS-PHY NRT analysis 
and forecast along root mean square model-observations 
misfits at weekly frequency for temperature, salinity 
and sea level anomaly. Considering the 2019 operational 
production, the BS-PHY NRT system is characterized by 
an error in temperature of about 1.8°C and of 0.25 PSU ir 
salinity in the layer 10-20 m. Below 20 m, the temperature 
error spans from 1.6°C to less than 0.2°C along the water 
column, while salinity error is between 0.4 PSU in the 
halocline and less than 0.2 PSU in the deepest levels. 
‚he nominal product for BS-PHY M [4] provides reanalysis 
for the past reconstruction of the physical ocean state In 
the Black Sea starting from 1993. Ocean variables included 
in the BS-MFC MY are identical to NRT, but as monthly and 
daily means. The BS-PHY MY system (E3R1 version) is basec 
an a new Implementation of NEMO v3.6 hydrodynamic 
model, at the same NRT system resolution but with more 
accurate bathymetry. It is also online coupled to OceanVar 
for the assimilation of reprocessed observations (insitu 
temperature and salinity profiles from merged datasets: 
NS TAC and historical SeaDataNet observations, sea leve. 
anomaly along track provided by SL TAC). It is forced by 
ECMWF ERA5 reanalysis atmospheric fields at 30 km 
horizontal resolution and 1 h temporal frequency. To 
improve the representation of warmer and saltier waters 
zoming from the Mediterranean Sea into the Black Sea, a 
damping to temperature and salinity profiles as provided in 
[5] at the Bosporus exit has been implemented. Sea surface 
temperature restoring with magnitude of retroaction of 
-:200 W/m?/K has been implemented using gridded L4 SST 
satellite data from CMEMS SST TAC. In terms of accuracy, 
*he new hydrodynamical model and data assimilatior 
jdevelopments in E3R1 guarantees a reduction of the 
arror in temperature (salinity) of about 50% (60%) with 
respect to the previous reanalysis system - version E2R2, 
aperational from 2017 to 2019 - (e.g., -0.6°C and „0.4 PSU 
in 0-10 m; a maximum error in temperature up to -0.7°C 
in average is provided in the 10-100m layer, while salinity 
error is extremely low - up to -0.05-0.1PSU below 100 m). 
Considering the accuracy in sea level anomaly, the new 
reanalysis exhibits a significant improvement with time- 
averaged root mean square deviation of 2.3 cm (versus 
3.7 cm in the previous version) (Figure 3).