Yes, the whistlers are amplified in the magnetosphere by
wave particle interaction.  The whistler wave steals energy
from electrons in the plasma, which then precipitate down
onto the ionosphere.   With careful monitoring of the phase
of distant VLF transmitters (suitably located), these
precipitations can be seen as a small rapid SID.

Bielefeld is, as usual, well placed for the lightning
storm off the southern tip of South Africa.  Receivers
a little further east may do very well too. I wonder if
Jacek has vtevent running?

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Paul Nicholson
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