Remedy 1: Operationalisation of a satellite – non-satellite matchups facility with appropriate discovery and user tools
Services that provide data extraction, analysis, and visualization tools exist for comparisons of gridded data, but are currently only rudimentary for comparisons of satellite and non-satellite fiducial reference measurements based on data co-locations, which are needed for the validation of satellite measurements and derived products. In particular, analysis capabilities that for instance allow analysis at different time or spatial scales are missing. While measurement uncertainties are at least displayed by some existing services, e.g., the FP7 NORS project, the visualisation of uncertainty arising from differences in spatiotemporal sampling is generally not included, but is needed to fully understand the uncertainty budget of a specific comparison.
The user survey undertaken by GAIA-CLIM indicated a clear need for such a capability to be developed. But challenges remain, because whatever analysis / visualisation tool can be provided, it will not necessarily match all individual needs. The GAIA-CLIM user survey also indicated that the analysis of the co-locations provided by the Virtual Observatory may not solely be used to evaluate satellite measurements but also vice-versa, the satellite measurements may be used to evaluate the quality of the reference measurements, e.g., their temporal consistency. Such a flexible tool does not exist to date.
GAIA-CLIM WP5 has developed a Virtual Observatory that addresses this gap partly for a limited set of ECVs and with several limitations concerning the representation of the mismatch errors. At the end of the GAIA-CLIM project, there will be a prototype tool that can be developed further in the future.
The tools to be developed to address this gap in the context of validation work should be based on the traceability principles and Cal/Val best practices referred to in G5.07. Hence G5.07 should be addressed before G5.06 as it represents a contribution to the latter.
Climate research and services have an increasing need to consider a large amount of observational data and model outputs simultaneously in applications. Because the data volumes provided by satellite observations and ensemble model runs have increased to levels that prevent easy download to local compute environments, there is an enhanced need for tools that provide functionality for data extraction, analysis, and visualisation at source or on cloud compute resources. At the same time, “fiducial” reference measurements are needed to provide evidence for the quality of satellite observations and models, but the aforementioned tools to exploit the potential of such reference measurements are currently only rudimentary. This in particular includes tools to analyse and display uncertainty of comparison results due to differences caused by mismatches in space and time of data used in comparisons.