Just look at the top of the Wipneus charts - they say 'from NSIDC sea ice
concentration data'.

Re the sea ice forum being moderated, what's the problem? You just need a
standard forum registration, wait a day or two for approval and you should
be in. I don't have any sense that it's any more difficult to join than any
forum that puts the small hurdle of registration at the entrance. Provided
you don't abuse the forum and stick to the rules then it's as open as any
other forum.