Book I'd like for Christmas...

The more I operate WSPR, the more fascinating I find the curious appearances of isolated spots, often from great DX distances, at times when general propagation is completely closed.

Oi!  Down here, Santa!

For the most part, this seems to be driven by Auroral Es, especially clearly seen in the dead of winter at 14MHz.

Searching for some research in this field, I came across the very well-written and eye-wateringly expensive The High Latitude Ionosphere and Its Effects on Radio Propagation.  Though now quite old, it's nevertheless a rare source of information on this niche subject, making copious references to the heady days of nuclear weapons research done in the 1960s.

I always have a queue of radio things to buy, so this one will have to await kind donations at Christmas, I think!