The CHARMe Project: Commentry Metadata for EO Datasets
Marsh, Kevin

A major impediment to enabling the wider use of EO and climate data is how they can judge if these data are 'fit for purpose', particularly as these data are now being used for increasingly diverse applications. Different users require different kinds of supporting information;. we term this 'Commentary' metadata, and includes both quantitative and non-quantitative metadata.

This can include include:
1. Post-fact annotations, e.g. citations, ad-hoc comments and notes;
2. Results of assessments, e.g. validation campaigns, intercomparisons with models or other observations, reanalysis, quantitative error assessments;
3. Provenance, e.g. dependencies on other datasets, processing algorithms and chain, data source;
4. Properties of data distribution, e.g. data policy and licensing, timeliness (is the data delivered in real time?), reliability;
5. External events that may affect the data, e.g. volcanic eruptions, El-Nino index, satellite or instrument failure, operational changes to the orbit calculations.

As yet, there is as yet no robust and consistent mechanism to link Commentary Metadata to the datasets themselves. CHARMe ("Characterization of metadata to allow high-quality climate applications and services") will provide these essential links, by creating a repository of Commentary metadata plus a set of interfaces through which users can interrogate the information over the Internet.

This will provide robust and reusable frameworks for linking datasets with Commentary metadata, as well as reusable software tools that allow climate scientists and users to exploit this information in their own applications and improved search, intercomparison and time-series analysis tools for large and diverse datasets.

The project consortium encompasses data providers, scientists, and developers of future climate services, who participate in major European investments such as GMES, ERA-Clim, ESA's Climate Change Initiative, the Climate Satellite Applications Facility and EURO4M. This will ensure that the CHARMe system is suited to the needs of diverse EO user groups.