Brief G7 disturbance

Another nice example of a brief G7 geomagnetic disturbance bringing about a large enhancement of a local signal from G0CCL (14MHz) overnight. 

The peak occurs almost precisely at the most southerly deviation of the field, and when the Raspberry Pi transmitter had switched, as it is set up to do, from a series of 5W to 0.2W output, which (subject to checking with G0CCL) made this an even more remarkable enhancement:

It's perhaps tempting to think that this peak is just the passing of the greyline or some other effect.  But that is not seen on quiet days, as the results for 28-29 August 2020 show (the ~02:30UT peak is broadly coincident with a minor southerly deviation in the Z component):

G0CCL 14MHz WSPR reception on a low Kp day.

Meanwhile, W8AC comes in at a slowly increasing level, then undergoes a very dramatic slump in strength as the Z component southerly deviation strengthens, then restores as the field rebounds, before vanishing completely.  I checked various other receptions to see if this was repeated.  The result from G4ZFQ/Y, which is a Yagi pointing across the Atlantic, I think, seems to confirm it was a real effect, allowing for latitudinal differences in the stations:

14MHz reception of W8AC by MW1CFN

14MHz reception of W8AC by G4ZFQ/Y