Remedy 2: Operationalisation and extension of the Virtual Observatory facility developed within GAIA-CLIM

The diverse sources of reference-quality data could be integrated with data made available through operational exploitation platforms, which could be developed for different user communities. GAIA-CLIM provides this as part of the Virtual Observatory for a set of atmospheric ECVs and the specific application of characterising satellite measurements. As a major part of the Virtual Observatory, a co-location database has been developed. The first step is to identify all pertinent satellite and non-satellite reference datasets that are of interest for a comparison to a given satellite sensor data. This could either be via a forward modelling approach to derive an estimate of the satellite-sensor data or a comparison to geophysical variables derived from the satellite data or both. The provided data need to be complemented by as complete as possible metadata and traceable uncertainty information, including comparison mismatch uncertainties that need to be derived from the comparison setting and the variability of the geophysical variable to be compared.

The Virtual Observatory has been developed to demonstrate the use of non-satellite reference data and NWP model data for the characterisation of satellite data. The Virtual Observatory integrates the different measurements, their metadata, quantified uncertainty for the measurements, and the uncertainty arising from the comparison process. Many other ECV reference measurements – satellite data combinations, e.g., for terrestrial and oceanic ECVs, are outside the scope of the GAIA-CLIM project and have not been addressed by this project. But these could be accommodated via operationalisation and extension of the service in the future. Such an operational service should involve unified access to the underlying reference quality non-satellite measurements used benefitting from proposed Remedy 1 to this gap.