eg 
SOTILLO. M.G.*2. GARCIA-HERMOSA, 1... DREVILLON, M.'. 
REGNIER, C.', SZCZYPTA, C.?, HERNANDEZ, F.*, MELET, A.’ , LE TRAON, P.Y.' 
Mercator Ocean International, Toulouse, France - *Puertos del Estado, Madrid, Spain - °CELAD, Toulouse, France - “IRD, Toulouse, France 
INTRODUCTION 
Useful information on scientific quality of the Copernicus 
Marine Service (CMEMS) products (such as error levels 
for ocean observations, or reliability of delivered forecast/ 
analysis/reanalysis model products) has to be provided 
to end-users in a consistent and effective way. A wide 
range of operational oceanography products, such as 
remote sensed or in-situ observations, and modelled 
outputs, are delivered by the Copernicus Marine Service 
for ocean physical, biogeochemical and sea-ice variables. 
It is, therefore, a challenge to establish and to implement 
required homogeneous product quality (PQ) procedures. 
The Copernicus Marine Service relies on PQ metrics and 
validation procedures inherited from MERSEA and MyOcean 
projects (Maksymezuk, 2016), and follows operational 
oceanography'’s best practices, well established within the 
GODAE Oceanview/OceanPredict international community 
(Hernandez et al., 2015; 2018). 
The Copernicus Marine Service product quality assessment 
strongly relies on the global ocean coverage provided by 
Sentinel and other satellite observations. Marine in situ 
observations are our main sources of information on the 
ocean and Its “ground-truth”. However, measuring at sea 
remains a troublesome technical challenge, and, despite 
a general source quantity increase during the last decade, 
ın situ observations are still sparse in the global ocean. 
Satellite and in situ observations are fully integrated in the 
Copernicus Marine Service system and in consequence, the 
aumber of valid observations and its evolution in time are 
primary key performance indicators and quality metrics. 
Modelled products provide Near-Real-Time (NRT) forecasts 
and analyses as well as Multi-Year (MY) reanalysis products. 
This article provides a synthesis of the Copernicus Marine 
Service PQ activities, the current organization and main 
user oriented PQ outcomes. PA information is disseminated 
to end-users (e.g., PQ metrics delivered through the web 
portal, updated in NRT) through highlights along with the 
specific PQ documentation for each product available 
in the catalogue. The PQ cross-cutting activity is under 
continuous improvement, and this paper indeed illustrates 
how PQ processes, firstly implemented during MyOcean 
Projects, have been standardized and reinforced during the 
Copernicus 1 service period (2015-2021). Finally, a brief 
overview of main guidelines to enhance PQ activities along 
the future Copernicus 2 service phase Is provided 
1. PRODUCT QUALITY: STRATEGY, 
PROCESSES AND ORGANIZATION 
The Copernicus Marine Service relies on a complex set of 
observing and modelling systems. Also, the generation and 
evolution of the products’ portfolio is characterized by an 
increasingly complex data (and software) management 
process. Apart from ensuring generation and delivery of its 
oroduct portfolio, the Copernicus Marine Service evaluates 
with quantitative metrics the scientific quality of its products 
and is responsible of Informing end-users about relevant PQ 
information. Thus, scientific PO documentation is issued for each 
product, and it is delivered alongside products at their release. 
To achieve its PQ objectives, CMEMS has outlined a PQ 
strategy and has established a product quality assurance 
Loop, across the different service elements and common for 
all producers. This PQ assurance loop is similar to generally 
adopted by other operational ocean and meteorological/ 
zlimatic services in terms of PQ issues (shown in Figure 1). 
User requirements and feedback (applied to all steps) 
zome first but they are not shown in the diagram as they 
are gathered and guide the production systems evolution. 
In one end there are the research and development 
activities that support the implementation of new products 
within CMEMS including: 
- those from production centres (PCs) and inputs from 
Service Evolution projects (see Melet and Le Traon, 
this issue); 
- other research programmes (i.e., H2020, Horizon Europe).