14MHz Transmissions to Iceland

Overnight, quite disturbed geomagnetic conditions, taking the Kp to ~5:

The only stations hearing my 1W AT 14MHz overnight were four stations in Iceland, EA8BFK, and G0LUJ (ground wave).  The ground wave signal, which can sometimes also show geomagnetic effects, was seemingly unaffected overnight:

It's always interesting to follow what happens with TF stations, as the path is about one skip long, and takes the signal straight into the auroral oval.  Here are the locations of the stations:

In general, as last night, the locations of TF4M and TF3GZ are sufficiently far north of the other two stations to put them on or near to the inner edge of the auroral oval:

Here's how TF1A heard me, showing peaks at 01:34 and 02:24UT, coincident with a rapid fluctuation in the Z field component.  For clarity of the variations, I've chosen to draw lines between data points, which artificially 'fills in' the absences of reports at times.  Your brain can easily work around this!

Meanwhile, at TF1VHF, the same peaks were seen, but with a +12 minute shift from those seen at TF1A (peaks at 01:46 and 02:36UT).  Curiously, the brief dip in signal strength at both TF1A and TF1VHF arises at the same time of 02:10UT.

These two contrast with the reception at TF4M, where the first peak at TF1A is not seen (TF4M confirmed as being active for hours before this time).  Indeed, unlike the other two TF stations, TF4M only starts to hear me at 01:02UT, 32 minutes before the first peak at the other two stations.  Strangely, the second peak at TF4M comes at the same time as at TF1A (01:34UT):

At TF3GZ, the first peak arises at 01:46UT, the same as TF1VHF, as does the second peak of 02:24UT for both those stations.  The dip in signal also occurs at the same time of 02:10UT:

Because TF3GZ is very close to TF4M (47km, or roughly 1 degree east), it's difficult to explain the 12 minute difference in peak signals between them.  If it were a longitude effect, the expected timing difference would be only 4 minutes.