WSPR Anomaly - PY2GN

Last night was quite unusual at 14MHz, where there had been minor disturbances throughout the day.  This led to the band remaining open at short skip distances into mainland Europe and even some moderate DX from the Middle East (4Z and HZ).

The single unusual spot of the night came from PY2GN at 00:20UT, with a SNR/2500Hz of -20dB.  This station does feature relatively often in the unusual spots list.

Now, the distance to PY2 is over 9500km - making a consideration of the likely propagation path an interesting one!  Here's the planet's situation at the relevant time:

How to account for propagation at this time?  Image: DX Atlas, with permission.

Now, the question to ask first is: is there anything unusual about PY2GN's location that might help understand the propagation?  Well, there is certainly the South Atlantic Anomaly to consider, because this is quite a significant feature of the earth's magnetic environment.  This is how it looks, as measured at about 500km:

South Atlantic Anomaly.  Image: Wikipedia/Steve Snowden/NASA

Who knows what effect this has in practice?  Certainly, ionisation is enhanced in this area.  Could the signal be running up the grey line to the north, being bent towards Wales by the auroral oval?

Or perhaps along the grey line to the south, again undergoing bending by the auroral oval when it gets to the north?

Or perhaps there are auroral Es drifting northwards from the southern aurora, and equivalent Es drifting south from the northern aurora, yielding a path?

Or is the path more direct, with the field of the inner Van Allen belt conveying the signal from south to north?  Can a WSPR signal stay coherent under such complex paths?

Or, finally, could it be the equatorial electrojet that is responsible?  This paper provides interesting food for thought.

Well, all we know for sure is that some path is allowing a coherent signal to make it to the UK.  Only with a coordinated effort at both stations, to try and measure time delays, could we make some progress.  Because of the infrequent nature of the event, this is not very easy to organise without particular determination at both ends.

Also interesting to note that the (northern) auroral prediction last night showed a distinct and persistent patch as far south as Spain.  It's still not clear if these patches are anomalies in the model, but there certainly were plenty of short skip signals coming in from Europe all night, so the patches might well portray real auroral Es:

Image: NOAA.

Looking at the southern aurora, the model again predicts quite extensive patches extending to tropical regions.  This shot is a few hours earlier than the PY2 spot, but the predicted patch would be drifting over the coming hours to the right, towards Brazil.