The validation diagnostics are defined in order to respond to 2 different objectives:
A main principle of validation phases including round-robin and final validation is to use a common set of validation diagnostics for all the algorithms or products (FCDRs and ECVS) which will be developed in the project. This strong principle allows us to compare the impact of different algorithm categories together with comparable statistics. This will be also a rigorous approach to characterize the sea-level altimetry errors better.
The validation diagnostics are composed in distinct types which allow us to check altimetry data with complementary objectives. These categories depend on the altimetry levels considered. For levels 1 and 2, there are 3 types:
- Intrinsic altimetry comparisons for 1 dedicated altimetry mission (A): objective is to ensure the internal consistency of new proposed algorithms compared to standard or reference and to measure the global system performances improvements. This family is noted “Global internal analyses” further in the document.
- Intercomparison between at least 2 missions and all the missions when possible (B): objective is to measure the sea-level consistency improvements between different altimetry missions using the new algorithms. This family is noted “Global multi-mission comparisons” further in the document.
- External data comparison using in-situ measurements (C): objective is to use independent data to measure the impact of new algorithms on the sea-level calculation derived from altimetry missions. This family is noted “Global altimetry and In-situ data comparison” further in the document.
Concerning altimetry levels 3 and 4, there are 2 types:
- Internal analyses of L3/L4 products (A): it is the equivalent of the “Global internal analyses” concerning level 1 and 2, but for L3/L4 altimetry products.
- External L3/L4 products data comparison using in-situ measurements (C): it is the equivalent of the “Global altimetry and In-situ data comparison” concerning level 1 and 2, but for combined altimetry products.