MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
In 2015, assimilated observations were: 
- satellite SST data (AVHRR data supplied by the 
GHRSST project), 
in-situ SSTs from moored buoys, 
drifting buoys and ships (considered unbiased and 
used as a reference for satellite SST bias correction), 
sea level anomaly from Jason-2, Cryosat-2, and 
SARAL/ALtiKa, 
sub-surface temperature and salinity profiles from 
Argo, underwater gliders, moored buoys, sensors 
carried by marine mammals and manual profiling 
methods, 
-sea ice concentration (SSMIS data provided by OSI 
SAF as a daily gridded product), 
The main upgrades to observation satellite usage 
during Copernicus 1 have been the assimilation of: 
Jason-3 (2016) and Sentinel-3A & B (2017 & 2019) sea 
level anomaly observations, 
AMSR2 (2016), Suomi-NPP & NOAA-20 VIIRS (2017 & 
2019) and Sentinel-3A & B SLSTR (2019) sea surface 
temperature data. 
These continual upgrades to observation usage, In 
combination with model upgrades, have ensured product 
Juality has either been maintained or improved over time. 
-igure 1 shows an example of the improved ‘Class 4’ statistics 
\Ryan et al., 2015) for temperature profiles against Argo data. 
Note that this specific comparison to PSY4 (the GLO high 
resolution system) for temperature profiles favours GLO-CPI 
and FOAM, whilst PSY4 shows improved error statistics for 
other variables, such as sea level anomaly or currents. 
A major achievement during Copernicus 1 has been the 
operational robustness of the GLO-CPL system, particularly 
following the upgrade to weakly coupled data assimilation. 
Very good back-up and contingency procedures are in place 
and, as a result, no extended outages have occurred and 
most delays to delivery have only been 1-2 hours. The 
system benefits from being relatively self-contained with no 
dependence on external forcing data or boundary conditions. 
For the last three years, the focus of research and 
development of the GLO-CPL system has been on the next 
major upgrade. This is now expected just after the end of 
Copernicus 1 and is represented by the schematic in Figure 
2. It will involve delivery of the GLO-CPL product from a 
coupled atmosphere-ocean system which is also being 
used for Numerical Weather Prediction. This involves many 
changes including upgrade of atmospheric resolution (to 
'0 km) and the inclusion of an ensemble at lower 
atmospheric resolution (20 km), both of which have the 
potential to deliver improvements in ocean products. The 
ocean component is also being upgraded to be consistent 
with the configuration now operational in the ocean-only 
LOAM system at the Met Office. Amongst other 
enhancements, this includes a new scientific configuration 
"GO6', Storkey et al., 2018) on the extended 0RCA025 grid 
and an improved variational bias correction scheme for 
SSTs (While and Martin, 2019). 
increased 
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ıgure z: Schematic showing some of the main changes developed for the upcoming upgrade of the GLO-CPL system (labelled as 'CPLDA). 
Pending final testing it is likely the atmospheric configuration will be GA8 (rather than GA7.1 as shown). The addition of the coupled ensemble 
provides areat potential for future ocean developments.