MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
NWS Analysis-forecast evolution 2015-2021 
X 
NEMO v3.4 (7km) 
Assimilation of 55T. 
9 * ERSEM coupled with PHY 
May!2015 ! No data assimilation 
CHY 
f 
Improved data assimilation 
Type of assimilated 
oObservations increased 
adding SLA and Tand 5 
profiles 
PHY - ; 
NEMO updated to ; ” 
WG Mari2016 | 
WAV — 
New: addition of a | 
WAVE model 
component at 7km 
| Adna 
= PHYWAV — 
A 2 
3 igh resolution: 
NMeowZ018 1.5km 
ERSEMupdatedto , _ G 
version 19.04 ] Dec'2019 
f 
Inclusion of a carbonate 
system for the delivery of 
pH and pCO2 products 
AG 
BGL 
3GU -— \ 
Tatal Chl data — 
assimilation } Dec 2020 
rn 
- PHY WAV =— 
Coupled PHY-WAV 
X 
'igure 1: Major evolution of the NWS analysis and forecast components during Copernicus 1 in chronological order. 
This restriction was overcome from more recent work 
oy developing the capability to assimilate SLA also in the 
shelf areas, which increased the accuracy of the model 
5SLA and of the water column physical properties. This Is 
an important achievement that will be implemented In 
operations in the next cycle of developments and in the 
next generation of reanalysis. R&D work has also studied 
the impact of future high-resolution observations on data 
assimilation. A series of Observing System Simulation 
Experiments (0SSEs) has been carried out to assess the 
potential impact of assimilating wide-swath altimeter SLA 
data from SWOT. The results of this set of experiments 
showed a clear positive impact off-shelf, but a smaller 
impact on-shelf. Further work will be required to assimilate 
SWOT observations with the expected large correlated 
arrors. 
At the beginning of Copernicus, none of the NWS systems 
were assimilating Chlorophyll or other biogeochemica 
variables. The assimilation of satellite total Chlorophyl 
was introduced for the first time in the reanalyvsis timeseries