A first phase of the project was devoted to the analysis of the situation. It ended as planned at T0+6 and led to the first project public workshop which presented the analysis and collected feedback from on the community and stakeholders on this analysis.
A first outcome of this phase is the publication of an updated list of cal/val requirements for all Sentinel missions (optical, altimetry, radar and atmospheric composition missions) presented in a unified way. A second set of documents presents a survey of existing cal/val data sources, including sensor pre-flight calibration, on-board calibration devices, vicarious methods on natural scenes, comparisons with other sensors and models, and finally with in-situ measurements from networks and field campaigns. The survey also addressed data distribution aspects. The document include an extensive survey of in-situ measurement networks relevant for all variables measured by the Sentinel missions, with an assessment of their maturity level and operational readiness. The assessment relied on published information as well as interactions with many experts (through questionnaires and interviews).
Morevover, a three-day virtual project workshop was organized and gathered more than 140 participants. The workshop allowed interactions between scientists and engineers from different domains to present their assessment of the status of the calibration and validation of the Copernicus program. Important topics to be addressed by the CCVS project were discussed: which measurements can be labelled "Fiducial Reference Measurements" ? How to ensure a sustainable funding for measurement networks ? Is there a need for a better coordination between measurement networks and cal/val experts ? What effort should be put on the maintenance of reference data archives for validation ? A document summarizing the main outcomes of the workshop was produced.
The second phase of the project was dedicated to the elaboration of the solution itself. This solution was elaborated thanks to two complementary approaches:
* in a "bottom-up" approach, the different avenues to improve existing Cal/Val methods have been identified
* a "top-down" approach was derived from a maturity assessment of the Cal/Val status for each Sentinel core product, and identify where priority actions should be applied.
The activity was also supported by several working groups. Dedicated working group meetings were held with the Copernicus Services and the Space Agencies.
A second workshop was organized to interact with in-situ measurement laboratories and networks. Discussions were held with international partners through CEOS WGCV meetings.
Four different types of recommendations were issued:
* R&D activities were proposed on Cal/Val method, ground-based instrumentation an on-board calibration technologies,
* Recommendations for operational activities to be implemented or supported,
* Organization and coordination activities involving several stakeholders.
The list of recommendations was then structured into an actionable programme with an assessment of the criticality and required effort.
Potential pilots and funding sources for each activity were identified, and a tentative implementation timeframe was provided.
In addition, a quantitative assessment of the propagation of uncertainties to Level 3 was performed for some products.
