Copernicus evolution: new concept for an innovative and holistic solution for Sentinels calibration & validation

The action should define an innovative and holistic strategy for the cal/val activities for and across all existing and planned Sentinels in an operational perspective to better access to the necessary infrastructure for Fiducial Reference Measurements.

A number of specific questions need to be addressed:

1. The clear identification of cross-Sentinels calibration requirements (from level 0 to level 1 data) and of validation requirements (from level 1 to level 2 data).
2. The clear identification of different cal/val sources: e.g. other satellites, on board calibration, in situ networks, regular airborne campaign, ad hoc site characterization with an overview of existing relevant networks, their distribution and current resourcing.
3. The comparative evaluation of various methodologies including those which are operational and those which are in a pre-operational status, evaluation of the steps needed to bring the latter to an operational level.
4. The project should design a comprehensive operational approach for medium and long term cal/val strategy for and across all existing and planned Sentinels with a particular focus on:
   1. The definition of appropriate reference networks and gap analysis with respect to existing ones, an assessment of the sustainability and operational status of the existing networks, an assessment of ""interoperability"" needs between networks;
   2. The definition of the characteristics and the location of optimised sites or “Sentinel supersite(s)”, or where necessary of supersite definition per domain (land, atmosphere and ocean);
   3. An evaluation of the direct impact on level 3 products when relevant;
   4. A proposed solution that should be modular and expandable in light of the potential future Sentinels in the context of the Copernicus evolution.
5. The linkage between EU and non-EU aspects of the networks needs and identifying the necessary non-EU partnerships to prioritise.
6. The definition of a long-term strategic reference scenario for the implementation of the required infrastructure.

Efforts should be made to establish counterparts and strong linkages with the international community working on issues relating to Calibration and Validation, in particular with the European Space Agency and EUMETSAT and established standards in place through the CEOS Working Group on Cal/Val and Quality Assurance for Earth Observation framework (QA4EO) as well as the operational elements in place through the WMO Global Space-based Inter-calibration System (GSICS).

The project should take into account relevant on-going coordination activities performed by the European Environment Agency (EEA) as the Entity entrusted by the European Commission to coordinate activities within the Copernicus In Situ component.

The project should also propose recommendations and establish a roadmap to develop this innovative “Sentinels cal/val concept” with specific reference to the “Copernicus supersite(s)” definition and their distribution, including considerations on data quality check, harmonization, traceability, distribution and conservation process of related information.

For proposals under this topic:

• Involvement of post-graduate scientists, engineers and researchers and promotion of gender balance is encouraged, for example through professional work experience or through fellowships/scholarships as applicable.

The Commission considers that proposals requesting a contribution from the EU of EUR 3 million would allow this specific challenge to be addressed appropriately. Nonetheless, this does not preclude submission and selection of proposals requesting other amounts.

Copernicus is addressing all domains of the Earth environment, including the atmosphere, the land (including inland waters) and the oceans. The EU environmental programme Copernicus implements six services that benefit significantly from measurements acquired by EO satellites, the so-called Sentinels series. The first generation of Sentinels includes 6 families of satellites (from S1 to S6), each family having 4 members (from A to D) and additional satellites providing complementary measurements to the existing fleet are foreseen in the context of the expansion of the Copernicus programme.

The utility of the large and growing volume of satellite observations and derived data products for operational services is crucially dependent on the proper calibration of the instruments and validation of the products. Global monitoring over extended periods is expected to require even more rigorous inter-calibration in the future.

These routine calibration/validation (cal/val) exercises are required in order to relate the space measurements to internationally recognized standards to ease comparability of satellite measurements taken at different times and locations, by different instruments and to facilitate cross-validation with other types of measurements and model output.

Cal/val activities are a fundamental aspect of the entire Copernicus programme as the essential connection between Space Component, in-situ Component and Services. Data sharing and data exchange principles and processes should be well defined and promoted by the Programme.

The dimension and breadth of such an operational programme calls for a commensurate instrumental support to perform the required cal/val procedures. Such procedures are currently implemented through existing infrastructures, which are strictly tied to individual missions, set up in an ad hoc manner by different agencies and institutions to provide the basic needed support.

The lack of sustainability in the maintenance of the calibration and validation infrastructures is clearly not in balance with the dimension of the Copernicus space component and its ambitions for evolution in future. Often there is a strong dependency on research infrastructures which is not fit-for purpose in the context of an operational Programme such as Copernicus.

Moreover, the lack of sustainability goes along with a lack of a holistic approach, e.g. a minimum set of standard instruments to be operated through optimised sites or ""supersites"", which would in addition enable an economy of scale. Such “supersites” of fiducial reference measurements may have to be domain specific to cover various geophysical media, but also across domains as the case for the atmosphere in particular. Many issues are at stake when setting up a ground-based network of fiducial reference measurements including the need for optimization depending on the foreseen applications.

• Consistent approach for the calibration and validation for and across Copernicus Sentinels
• Coordination of networks and space agencies and institutions contributing to Copernicus Sentinels cal/val activities