Remarkable WSPR Spikes

There was a forecast yesterday for a sudden transition from Kp ~1 to Kp ~4 into the magnetic midnight period in the UK.  Again, it was time to listen to what happened to WSPR signals as the disturbance progressed.

There's a lot of data to process, but a couple of signals really stand out already.

First, here's how the geomagnetic field (horizontal component) varied:

Image: Tromso Geophysical Observatory

In essence, the field rapidly commenced its disturbance at 22UT, and equally suddenly relaxed around 02:30UT onwards.

Here's how G0CCL's signal, only 353km away from me, responded:

The clearest method to plot this was with a stepped line, which works very well, except for the fact it masks the signal dropouts as the disturbance commenced and restored.  This is how it looks without connecting lines:

But the most incredibly dramatic effect is that as the field snaps to quieter conditions - two sharp peaks, increasing the received signal by about 25dB (a factor of 316), between 02:26 and 02:50UT!

That is, without doubt, the most incredible effect of any geomagnetic disturbance I've ever seen.

The effect was also seen, in a somewhat different pattern of even more pronounced peaks, in the example of ON7KB's signal.  ON7KB is 17 minutes ahead of G0CCL in terms of Earth's rotation, but notice how the increase in received signal happens a full hour before G0CCL:

It's a good thing that these two stations, at least, are transmitting the high, 5W output that they have chosen to use.  That's because those following the trend of very low outputs of 0.1-0.5W, whiilst they do climb sharply out of the noise and into detection as the field changes, they only do so for three or four spots.  Whilst that clearly highlights the effect of the changing field, it doesn't make for a very good plot.


No doubt there are more surprises in the depths of the dataset, which is safely stored and awaiting analysis...