At present, nearly all of the openings on the 28 MHz band are during the daylight hours. The solar flux is roughly around the 100-120 mark and there are some F2 layer openings during daylight hours. There is also some mid-Winter Sporadic-E at times but again, this is during daylight hours.
14th January 2022: At about 22:30 to 22:45 UTC, Tom SP5XMU in Poland was one of those who caught an opening to the west coast of the USA on the 28 MHz band. For Tom, this would have been around 11:30 PM.
This is highly unusual and worth noting. It's about 7 hours after the sun has set in Poland so it can't be easily explained the position of the sun and it is also a very northerly path.
At the bottom of this post, I have the FT8 log for SP5XMU for this opening and it shows that there was an opening to Scandinavia at the same time from Poland.
Tom wasn't the only person to catch this opening. Further down this post, I have a list of spots from European stations of US stations on 28 MHz. It suggests that the main opening lasted from about 19:30 to 23:15 UTC.
Auroral-E: It is probably no accident that this opening from Poland to the USA coincided with an aurora and a high k-index of 5-6.
It wasn't the typical 'aurora' where signals are spread out and distorted. After all, digital FT8 signals were being decoded. Instead, it was likely to have been auroral-e propagation.
Distance: However, the distance from SP5XMU to the stations on the west coast of the USA was in the region of 9,000kms. Aurora-E as the name suggests forms in the E layer of the ionosphere and the maximum range from one hop would be in the range of 2000-2300 kms.
That leaves a huge gap of about 7000kms in the path to the USA.
How did the signal get from Europe to the west coast of the USA?
Multi-hop auroral-E?
Some form of chordal hop auroral-E?
Did it couple into some ordinary Sporadic-E or F2 layer at the western end of the path?
I've seen a lot of people just explain it away as 'Auroral-E' but it's more complex than that. That's what makes this type of opening so interesting.
50 MHz: I checked the DX cluster and I could see no spots for an opening from North America to Europe on that band.
DX-Cluster spots for European stations spotting the USA on the 28 MHz band...
