Hi Lu,
Thanks for this post about the complexities of copyright and the challenges of attributing ownership, especially when multiple agencies and levels of ownership are involved.
I am reminded that in legal copyrights cases, the courts typically look for "due diligence" in following copyrights, so personally, I would accept the Eumetrain statement at face value, and not bother to dig deeper, assuming that the authors did that. At some point we just have to be reasonable I suppose. I was happy that Vesa and Jarno included such a complete copyright statement, and that it matches CC statements so well, which made me comfortable in reusing the resource if I wanted. If in the unlikely case of being challenged for copyright infringment, I think the burden to establish ownership would then be between Eumetrain and EUMETSAT/ECMWF to agree. Since the rights have remained for some time as written, I would feel comfortable that I could use the resource as described.
Patrick