RE 
"eCI A. LE TRaON, DL.Y. 
Mercator Ocean International 
INTRODUCTION 
The Copernicus Marine Service (CMEMS) is highly 
dependent on the timely avallability of comprehensive 
satellite and in-situ observations (Le Traon et al., 2019). In 
situ and satellite observations are used, through data- 
assimilation, to constrain the analysis and forecasting 
systems, and validate their outputs, and to provide high 
level products to downstream users. 
Change and transformation in the Copernicus Marine 
Service is inextricably linked to data supply and the proper 
specification of requirements. The core dependency from 
upstream data must be managed strategically to ensure a 
steady data flow, and that new requirements are regularly 
included in observing plans of upstream data providers 
‘'Mercator Ocean, 2016; Le Traon et al., 2019). 
To manage this core dependency, Mercator Ocean 
international (MOi) has established coordination 
mechanisms with upstream satellite and in-situ 
coordination bodies (ESA and Eumetsat for satellite, EEA, 
EuroGOOS and EMODnet for in situ). 
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di: Sentinels data intearation In CMEMS