Progress of a 6m opening to Japan and South Korea

I have referred to this 50MHz opening from Scotland to Japan and South Korea on 23 July 2023
before. You can find it mentioned here.

Since then I have tried to follow the progress of the opening on a map. Here is the list of contacts on the map listed by time of working ...

50MHz stations worked at GM4FVM on 23 July 2023

You will probably need to click on this image to enlarge it to see the detail.

With two outlying contacts, the opening started on Hokkaido at 06:51 and then moved progressively down the East Coast of Japan until 07:52. At that stage I became interested in working South Korea and spent a bit of time trying to work three stations there. Between 08:03 and 08:22 I worked 3 stations in South Korea and three more in Japan, after which the opening faded out. 

There was a fairly steady progression down the East Coast of Japan and only real outliers were two contacts back in Hokkaido at 07:58 and 08:01, which I have marked with grey hatching. There may have been gaps when the propagation did not make landfall and the band was open to areas of sea.

Of course once a station has worked me, they are not likely to work me again. You tend to see the front of the propagation moving, while the band is still open for a while behind the front but those stations have already worked me. I think that the reversion to those two stations in Hokkaido does not necessarily mean that there was a new opening, but rather a couple of new stations have come on the band.

We have seen this type of thing before during single hop openings, for instance as reported here in 2019. The pattern of Es contacts moving in a (more or less) steady line over time seems well established. But it was interesting to see it happen at the end of a multi-hop path as far as into Japan. Is this multi-hop Es? Certainly it looks like Es at the far end. I suspect that a similar analysis viewed from Japan would have seen the propagation open in a path across Europe or the UK.

What we do not know is how the signal gets between Es at my end and Es at the far end, I am having doubts about whether the "bit in between" can really be multi-hop Es. If Es moves the way we can see in single hops or at the end of a long path, then similar moves along the path to Japan would knock the whole thing off after a matter of minutes. If there were several hops all inclined to move along as we know Es does, then the geometry would mean that the overall path would be lost very quickly.

I do not have anything to suggest for mechanism working in the "bit in between". A special type of polar propagation has been suggested and who am I to disagree? It would have to be pretty stable to work for  75 minutes over a path several thousand kilometres long.

Anyway, it was interesting to see the same pattern of contacts moving across the region but this time at the end of an extended path stretching as far as Japan and South Korea.

73 

Jim GM4FVM