G1 Activity, and a delayed WSPR effect.

The geomagnetic field was quite disturbed yesterday, reaching KP = 5 around the middle of the day (20/04/20).

This is the OVATION modelled aurora image at around the time of peak activity:

Image: NOAA/SWPC.

The magnetometry looked like this:

Disturbed earlier in the day, but quiet by evening.  Image: Tromso Geophysical Laboratory.

From about midnight onwards on a quiet geomagnetic day, I only hear groundwave WSPR signals near the limit of detection (usually around -30dB) from the UK and Ireland at 14MHz.  Only by about 04UT do signals from afar start coming in.

But last night and early morning, I was hearing LA6GH strongly, which the top plot shows is entirely anomalous in never having occurred in the preceding evenings (the relevant period is highlighted for each day in blue box).  The receiver runs from late evening to mid-morning, not daytime, but that is immaterial for this discussion.  The lower plot 'zooms in' on the detail of 20-21 April (long horizontal lines indicate periods during which no signal received):

LA6GH 14MHz 100mW WSPR received at MW1CFN.

Much the same was seen with the 5W signal from OZ7IT, where signals within the last shaded period at right (20-21 April 2020) are clearly seen as anomalous, relative to the same periods in earlier days):

OZ7IT 14MHz 5W WSPR received at MW1CFN.

It seems this is a result of ionisation 'patches' remaining in circulation in the ionosphere, several hours after the peak geomagnetic activity.  Nothing very unusual, but a nice clear example of enhanced propagation, all the same.  Apologies for necessary laxity in axes labelling, etc - these plots and posts take a long time to prepare!