Neither. The stations are in Japan. Imagine a line going from each of those stations to the satellite. Where this line crosses the ionoshpere that spot is what is measured. That is what you have information about. Those spots are the dots.

So you basically see the arc of the Japanese islands projected up towards each satelite which is visible from these stations. When the satelite is low on the horizon this projection seems to move fast, and when it is near the zenit it seems to move slow. This is what you are seeing with the dots.

Their location is calculated here: https://github.com/tylerni7/missile-tid/blob/main/tid/tec.py...

"Given a receiver and a satellite, where does the line between them intersect with the ionosphere?"

And then that is called here: https://github.com/tylerni7/missile-tid/blob/00c5fd25e2ab3c2...

"The locations where the signals associated with this connection penetrate the ionosphere."|

I would guess the moving dots are fixed GPS receivers, or more precisely the intersections of lines between fixed GPS receivers and moving GPS satellites with a sphere around Earth representing the ionosphere. If you look at the shape of the moving clusters, some look like Japan.