GSC Sentinel-2 PDGS SRD - emits - ESA

ESA UNCLASSIFIED – For Official Use
GSC Sentinel-2 PDGS SRD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-RD-09-0028
page 31 of 204
stamping of the quality of all products generated before they are made available to
their intended users;
○ A central Archive and Inventory (AI) function closely coupling data sources and
data sinks, in charge of storing, registering and serving the product data and
associated inventory records to other functions;
○ A complementary Long-Term Archive Service function (LTA) responsible for longterm
archiving and preservation as well as bulk reprocessing of Sentinel-2
products. It aims for an optimum reuse of existing ground-infrastructure in the LTDP
area in synergy with other Earth-Observation missions. As such and whilst being
procured as an external service implementing well-defined Sentinel-2 PDGS
interfaces, it is intended to be federated within the overall PDGS through collocated
Sentinel-2 PDGS specific functions.
○ A Data Circulation (DC) function responsible for all product exchanges between the
distributed PDGS archives and more generally centralising the data exchanges
between interfaces whether internal (between co-localised sub-systems in a PDGS
centre) or external (e.g. versus FOS and auxiliary data providers, between centres,
etc);
○ A Precise Orbit Determination (POD) responsible for providing precise orbital data
for MSI data-processing via the DC and AI functions. This function aims for reuse of
a generic multi-Sentinel POD element. For Sentinel-2, POD orbit products will be
used as a contingency solution should the strict processing of the on-board GPS
and AOCS data embedded in the IDP Level-1 algorithms not provide the level of
accuracy required to meet the product geometrical quality requirements;
○ An Auxiliary Data Supply (ADS) function in charge of generating all other auxiliary
data required to the Level-2A MSI processing. This function is aims at being
mapped directly to the external data-sources identified in [RD-4].
○ A Data-Access Index (DAX) function responsible for federating the product
inventories spread throughout the PDGS and providing the front-end services with
a consolidated virtual view of the archive. It is in charge of transparently
maintaining the relationships between the product components and their physical
remote location and serving them to the data-access elements when performing the
actual download operations;
○ A Data-Access Gateway (DAG) function acting as a single virtual access point to all
PDGS data products and implementing the actual downloads. It is in charge of the
transparent re-assembly at the user site of the final products from the granular
product elements scattered throughout the archives;
○ The Front-End Services (FES) responsible for answering to the end-user dataaccess
activities include the following PDGS functions:
o The Multi-Mission User Services (MMUS) function responsible for user
interactions supporting catalogue queries and subsequent triggering product
downloads based on the DAG function;
o The On-Line Image Browser (OLIB) function responsible of the true-colour
image (TCI) publishing service towards the general public.
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