The basic principle of validation diagnostic is to compare the new algorithms or the new product with the reference ones. The reference algorithms or products are the state of the art at the beginning of the project.
Therefore, for each new algorithm or new product, a set of common validation diagnostics will be systematically performed in order to evaluate its quality and its potential improvement in comparison with the reference one. The diagnostics generated will be concatenated in a report available for all the round robin-participant (see dedicated section further).
The list of these common validation diagnostics are defined in annexe of this document using a standardized format file. The diagnostics are classified by type (intrinsic, intercomparison, external) and declined for each kind of input data. A short description and objective is given for each of them to illustrate their role and their interest.
Thanks to this synthesized files, all the round-robin participants could understand the role and objective of each diagnostic, and therefore bring their own expertise to choice the best algorithms or to analyse/describe the final sea-level ECV products.
Although, the main idea is to use a common set of validation diagnostics as already explained, it could be justified for some of them to use dedicated analyses only applicable for a specific algorithm. It could be for instance the case for algorithms concerning high latitude issues where global analyses are not adapted. In this case it could be necessary to adapt the global diagnostic to regional areas.
In addition, if external diagnostics provided by external participants seem to be relevant for the selection of the best algorithms, it is of course recommended to add them in the RRDP report.