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A concerted effort is planned for Q1 and Q2 2019 to gather existing material from across multiple GSICS and WGCV activities to place the specified recommendation on the CEOS website by Q4 2019.Confusion on the intent of the work plan caused delays in completing this item during 2018.  Clarifications at WGCV-44 led to an updated completion date of Q4 2019

A joint WGCV GSICS workshop 'An SI-Traceable Space-based Climate Observing System'  hosted by UKSA at NPL in the UK was held in September.  The workshop attracted nearly 100 participants and considered the needs, state of the art and prospects of how to achieve L1 traceabiliy and satellite to satellite interoperabiliy to meet the most demanding needs of climate. However, it was recognised that steps required for climate would result in the necessary benefits for science and operational sensors. Although the 3 day workshop concerned primarily optical sensors (UV to TIR) it also addressed the needs of passive microwave as well. The conclusion of the workshop was that whilst every effort should be made to incorporate all comparison knowledge from vicarious earth surface and Lunar measuremnts, comparison to a well-calibrated reference sensor over a range of geogrpahical locations was a solution to be strived for.  These reference sensors should be SI-traceable and have been given the generice name of SITSATS (SI Traceables Satellites) with current examples being CLARREO Pathfinder, TRUTHS and a proposed Chinese mission called CRABS. 

The output of the workshop will be a community white paper (Dec 2019) and a peer review porceedings early in 2020. It is believed that this white paper will provide a top-level strategy for this task and with it establish a framework for sub-tasks that will need to be continued and developed further to facilitate bias analysis for both main stream sensors and new space constellations . Notalbly, Lunar model improvement, methods to carry out sensor to sensor comparison and vicarous test sites including the operational RadCalNet and methods to mathematically combine the results in an effective and robust manner..  

At the IVOS meeting, we agreed to create with some urgency, a template to record uncertainties and evidence of different methods used to assess and/or correct biases of level 1 for optical sensors, (the necessary pre-requisite for interoperability) which could then be made visible through the cal/val portal.  The content supplied would need to be peer reviewed and we agreed that this would be done through the IVOS membership, at least in the first instance. This set of templates, summarised in a table will then provide the means for the user community to assess and select appropriate methods to meet their needs for interoperability based on the nature of their mission.  This we can do by Q2 2023 and will close this action.  We will look to see how we can optimally combine the results of different methods in a more holistic manner but this is much more complex and whilst desirable and may have been our original intent, we would see this as a follow-on action, needing a dedicated face to face workshop with the above information available for a variety of missions.  With Covid this has not been possible and will probably not fully take place for a year at least delaying the conclusion of this action.

As an extension to this deliverable, a Radiometric match-up database is being developed to collate and compare imagery/radiometry over a set of CEOS sites to define a reference. This initiative was also emphasised during the presentations at the IVOS meeting and VH-RODA workshop in 2023.

Reference sites have been proposed, and we encourage observations from sensor operators, particularly those from 'New Space,' over these sites. Operators are encouraged to provide Top of Atmosphere (ToA) radiances or reflectances to contribute to the database.

The activity has reached a stage of maturity where we are ready to initiate a prototype phase, with plans for a demonstration at the upcoming WGCV-53 meeting.




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Seeing the workshop proceedings are not due until early 2020 does this deliverable need extension to Q12020?

At the last IVOS meeting a few weeks ago, we agreed to create with some urgency, a template to record uncertainties and evidence of different methods used to assess and/or correct biases of level 1 for optical sensors, (the necessary pre-requisite for interoperability) which could then be made visible through the cal/val portal.  The content supplied would need to be peer reviewed and we agreed that this would be done through the IVOS membership, at least in the first instance. This set of templates, summarised in a table will then provide the means for the user community to assess and select appropriate methods to meet their needs for interoperability based on the nature of their mission.  This we can do by Q2 2023 and will close this action.  We will look to see how we can optimally combine the results of different methods in a more holistic manner but this is much more complex and whilst desirable and may have been our original intent, we would see this as a follow-on action, needing a dedicated face to face workshop with the above information available for a variety of missions.  With Covid this has not been possible and will probably not fully take place for a year at least delaying the conclusion of this action.