Think of the earth as a giant magnet. But don't get north and south
confused--it is easy to do when you try to apply Fleming's laws or if
you are more advanced--Maxwell's. I will assume few readers can track
with vector calculas.
Say you are in the woods. You have a bar magnet called a compass. It
points you north, or more correctly, it points you towards eastern
Canada. The magnetic north pole is hardly fixed, on the geographic
north pole or otherwise and it can move 40 kms in a day! So, there
you are, looking at your magnet and it points in the direction of
north. Your compass is a bar magnet that indeed has a north pole--
that points north.
Since opposits attract--it means the north pole is a SOUTH pole!!!!
Otherwise your compass would point south. Get it?
Alright. The past weekend the solar wind moved northward. It remained
elevated as it has been the past couple weeks, but it moved from a
southerly orientation to a more northerly. When it was southerly
there were some northern lights dancing in the sky, but they have
subsisted with the change. The SOI was likewise strongly negative,
and even though the solar wind remained strong, now the SOI is
substantially less negative. What happened?
The earth's EMF became distorted with the southern directed wind
where positive ions raced strongly toward a negative pole--the south
pole. Now the stong positive charges are moving to the positively
charged north--and the SOI dropped.
It's all electrical, baby.