The happy Mid-Summer DX time, but lots of hard work

Two of the more gripping radio spectacles at Mid Summer are the fleeting appearances of DX during Two Metre Sporadic-E and the Mid-Summer paths on Six Metres linking Europe with Japan and neighbouring countries. These are completely different processes but my operating procedures for both have evolved to become similar.

I might also add Ionoscatter, but I did not hear any this year, unlike previous years. You can read about my experiences with Ionoscatter by searching for that word on this site.

The key features of these unpredictable phenomena is that they only last for brief periods, and the stations are often only heard for even shorter periods. Basically if I blink I miss them. Having said that, if you have the time and the opportunity (and a lot of patience) you can find them fairly reliably.

What links them is that the skills needed are more akin to a fisherman casting their fly into the river than reliable radio operation. Any fisherman knows that you have to cast a lot of times before you get a fish to bite. Patience and determination are the keys to success. 

On Six Metres this path is often called a "solstice" one, suggesting that it occurs directly at the solstice i.e. 21 June (or a day either side depending on the leap year status and other factors). In practice I have found it between 2 June and 23 July. For the purpose of this analysis I am taking the path as being possible on one month either side of the solstice, i.e. between 21 May and 21 July, which is when I usually look for it. Peak time of day is often quoted at around 08:00UTC at the European end, but I have used it between 05:59 and 09:47.

As I write this on 23 July I am assuming that these propagation modes have closed for this year ... maybe not!

This year (so far) has produced these results:-

50MHz contacts at GM4FVM over 8000km 21 May to 21 July 2025

Click to enlarge images if needed, as usual.

At a detail scale you can see the spread across Japan was different on each day. The 23 June opening was to the South and West of Japan:-

50MHz contacts at GM4FVM over 8100km on 23 June 2025

Whereas the 25 June opening was the North and East of Japan, and there was no overlap in terms of squares worked:-

50MHz contacts at GM4FVM over 8100km on 25 June 2025

I posted about the 23 June opening here and for this post I have corrected a data flaw (yes, even I do get those). 

Lest this look like a simple prospect to operate I have to point out that there were only two days in that two month period when I was able to use this propagation mode. That meant 60 days sitting doing very little and 56 minutes of action across two days.

50MHz Es openings 2025 at GM4FVM
Opening	Start time (UTC)	Duration (mins)	QSOs	DXCC	Squares
23 June	08:31	29	7	1	6
25 June	07:34	27	7	1	5
Season Totals		56	14	1	11

So is all that listening for 15 contacts really worth it? Well, distances ranged between 8478 and 9216km, with best DX being to JM1SZY in PM95 square. The distances covered make it worth it in my opinion. 11 squares worked make it better, but those were all in one DXCC this year.

On two meters the outcome was different but as we shall see, the operating tactics were much the same. 2m Es can occur at any time of year but it is heavily concentrated on either side of the solstice. Openings are unpredictable, infrequent and sometimes very short.

144MHz contacts at GM4FVM on Sporadic E 21 May to 21 July 2025

This year I had 28 contacts in 7 DXCC on 2m Es. Of these, 14, half, were in Italy. The rest were Switzerland (6), Spain (3), Germany (2) and one each in Bosnia-Herzegovina, Croatia and Serbia. Distances were between 1190 and 2234km with best DX being to YU5C in KN02. There were 16 squares worked.

144MHz Es openings 2025 at GM4FVM
Opening	Start time (UTC)	Duration (mins)	QSOs	DXCC	Squares
3 June	15:44	24	2	2	2
4 June	10:19	54	20	4	13
19 June	13:00	28	3	2	3
20 July	11:38	4	2	1	1
20 July	12:57	2	1	1	1
Season Totals		112	28	7*	16*

* The Season Totals figures are lower than the individual openings due to some squares and DXCCs being worked on several occasions. 

112 minutes operation across 4 days, and then 58 days not working any 144MHz Es. Is this a reasonable result? Seven DXCC, 16 squares and 27 contacts is a good 2m outcome for me.

Around Mid-Summer, 2-metre Sporadic E occurs fairly regularly somewhere in Europe. Sometimes it happens every day for a few days. The downside is that the areas covered are very small, with the result that the chances of 2m Es happening here on any specific day are fairly low. You can of course sit and watch PSK Reporter as it shows you lots of QSOs going on (apparently) all over Europe. Sadly, these openings are limited to small areas, sometimes to just one station at each end. For those stations the opening might last long enough for one QSO, or possibly only a partial QSO. If they are lucky then the propagation will stay open at their end and move on to somewhere interesting at the far end. Or not ... for many days I can only watch as others work hard for a QSO. And then again sometimes I work a string of stations.

The Mid-Summer 6-metre openings to Japan are in some ways similar in the way stations appear and disappear quickly. The method of propagation is totally different. On 2m Es is almost always single hop, out to about 2,200km. With the Japan openings it is multi-hop and the range is about 9,000km. Calling it a "Japan" opening is shorthand as I have worked into Asiatic Russia, South Korea and China during these openings. This year, however, all my contacts were into Japan, just one DXCC.

Either way, the method of operating I adopt on each band for this purpose is different from my normal one. With stations appearing and disappearing at such speed I have to abandon my usual attempts to complete a QSO at all costs. Instead, the only method that works for me during these events is a slash and burn approach. Anyone who has ever played the arcade game of "whack-a-mole" will understand. 

Result of these short openings - MADNESS. Sometimes three stations call me, I have to pick one to reply to. Often the one I pick has gone and the other two are still calling. Do I call the strongest with me, or the one giving me the best report, as most likely to still be there in 30 seconds? 

I therefore dispense with my normal practice of sticking with contacts as long as possible in order to complete. If one does not complete, then I move on quickly to give the next one a chance. Over the years this has proved to produce the best results at GM4FVM.

I think that the very fact that I do not know when or if these paths will open is what attracts me to them. If I wanted to work stations every day I could just go to 20m. I don't like 20m. I enjoy the effort you have to put into DX on VHF and UHF. Sometimes nothing happens - some years I have only had one 2m Es contact during the whole year so 28 is pretty good going. This year I worked one 2m station twice. It is in fact unusual for me to work one station twice in a year - usually the searchlight roams widely and rarely passes over the same point.

And when it does happen the operating is fraught and exhausting. I am looking for new squares and longer distances so I have to make quick decisions as to which station to reply to. Strangely, I enjoy this part of the deal too. 

I cannot really justify the effort. I just enjoy it when it pays off.

73 Jim

GM4FVM 

2 June 2025 Aurora

I am not sure how to define DX. Obviously it depends on the band in use. As a generalisation I might define it as stations I can contact which I would not usually be able to reach. This handy definition covers those situations where the activity is low as well as places where the propagation usually prevents a contact.

During the auroral opening from here on 2 June 2025 my understanding of this was a bit stretched. Some of the closer at hand stations I might have worked on a slightly raised tropo day. On or two I might have scraped through to on flat band conditions, but the result would have been scrappy. However, yesterday they were not just workable but they were all out loud on the loudspeaker. I might add, distorted and muffled on the loudspeaker --- but definitely loud.

There was plenty of early warning of this aurora.

Solarham warning of likely auroral activity on 1 June 2025

Despite the shockwave arriving on 1 June, the main effects of this strong solar event did not produce the desired result here until 2 June. I was listening on 1 June and it seemed as if I had missed the action, but the NOAA predictions showed activity extending over three days.

NOAA predictions for 1, 2 and 3 June 2025 made on 1 June 2025

It is quite possible for there to be a high K number at one stage but for the polarity to be moving north, in which case no enhanced conditions apply, and then for the polarity to head south and the band to open later. As it turned out, the magnetometers continued to see-saw during 2 June and conditions suddenly improved.

GM4PMK magnetometer on Mull, showing 2 June (top) and early 3 June (bottom)

I first tried 50 and 70MHz after around 11:00 without result. I could see people making contacts but there was not much happening here. I sometimes look at the FT8 waterfall while beaming at about 30 degrees, and if that shows dispersed traces something is happening. I could see MM5DWW on Orkney ranging in and out of auroral propagation on 50MHz. Sometimes I could copy him on FT8, other time his signal was wide and sounded auroral.

I could not raise anyone on either 50 or 70MHz. However, I had been watching DXMaps and I saw that various Russian stations were making contacts on 144MHz via aurora. Oddly they were posted as JT65 but the text said they were Q65c. They were also appearing on PSK reporter as Q65. So, more in hope than in expectation I went to the frequency they were listed as using (144.116MHz) and tried calling. No result. 

Due to the rotation of the Earth relative to the Sun, the effect of the aurora varies over time. This produces the "auroral oval" which is like a collar around the poles which varies in thickness. Usually the oval is thinnest in the mornings and as the Earth rotates the thicker sections appear to the north of me. In this case due to the high level of solar activity the ovals were predicted to be thicker than usual and therefore strong, but I still needed to wait for the widest portion to approach my part of the world.

Prediction for auroral oval for 1 and 2 June 2025

Note that these predictions made at around 05:00 show the aurora extending well down into the United States, while GM is at the back of the globe where a thin to non-existent thickness of aurora exists. In such situations there is nothing for it but to wait for the Earth to turn and bring a thicker part of the oval into my area of operations. This often happens in the early afternoon. Note also that the oval is very large, so this was clearly a major event.

It is often possible to wait of a thicker part of the oval to arrive, only to discover that the polarisation has gone against me by then. On 2 June, though, it went well.

I was listening on 144.116. This seemed an odd choice, but that was where the Russian activity was. Having said that I decoded nothing to start with. About to give up I heard something on the loudspeaker. Pursuing this, I had to turn the beam from my usual 30 degrees to 54 degrees before I found PD1BHZ calling CQ. After that contact I worked 16 stations on Q65-30C, all with the characteristic distorted auroral sound. These were 5 x PA, 4 x G, 4 x DL, and one each of EI, OZ and ON. Best DX was to Ronny DL1RNW in JO62, at 1039km. The event ended here at 17:15.

144MHz auroral contacts at GM4FVM on 2 June 2025 

Map made using  K2DSL mapping. As usual click images to enlarge if necessary.

Whilst none of this involved excessive distances, it was still very interesting. Most contacts were between east and south suggesting that the oval was indeed wide. Usually in smaller events the oval is further north and contacts tend to be more northerly. Also for the same reason the azimuth was further south than usual, between 40 and 54 degrees,whereas usually 30 degrees or less is what I find best. The benefit of reaching this area is that there are a lot more stations than to the north where I more often work.

DX, to me, is not solely determined by distance. These were stations I could not have expected to work so that is good enough for me. 

All in all an interesting opening. Although the predictions suggest the chance of another event today, I am not sure. It is that type of uncertainty which makes VHF DX-ing interesting. 

 73 Jim

 GM4FVM

A good tropo opening to the East

The Hepburn Tropo map (link on the sidebar) suggested that 10 December might be pretty good for tropo...

Hepburn Tropo Index 10 December 2024

As usual, click to enlarge images if necessary.

10 December was indeed a good day for the higher bands here, and conditions were still a bit enhanced until early afternoon on 11 December. I saw good conditions after that, but mostly for stations further south than me. From here there was nothing much to report later on as the high pressure slipped off to the east.

I had the first contact which indicated things were looking up on 9 December when I worked LA9AKA at +07dB. Once things began to get going the next morning I had 64 more QSOs on 144, 432 and 1296MHz.

On 144MHz I had 20 contacts, best DX being to UA1WCF in KO55 a distance of 2034km. This turned out to be the first time I have worked UA on tropo. Previous contacts on meteor scatter and moon bounce might have been greater distance, but I do find it satisfying to work long distance on tropospheric propagation. The contact with YL2LE was also my first into Latvia on tropo. I increased my total square figure by three squares.

144MHz contacts at GM4FVM 10 to 11 December 2024

As usual these days I tend to leave 2m behind and head for 70cm during a "lift" in conditions. I had 40 contacts on 432MHz, including to three new countries - Latvia, Lithuania and Estonia. Best DX was to LY2WR in KO24 at 1726km. These are not quite distance records for me on this band, but they do show that I have never done so well due east from here. My best distances are to the south. That makes this a good opening for me, adding eight new squares too.

432MHz contacts at GM4FVM 10 to 11 December 2024

1296MHz was also productive, especially at the start of the lift. Despite only making four contacts, I was happy to reach two new squares in Sweden. Best DX was to SM0DJW in JO88 at 1242km. I reckon that I could have done more on 23cm if I had tried more modes and if I had done more listening. The big limitation on 23cm for me is the lack of activity that I can find. I stayed on the KST microwave site for the duration but most contacts do not seem to be made that way. More work is needed if I am to make 23cm as productive as it can be.

1296MHz contacts at GM4FVM 10 to 11 December 2024

That was a good opening in a direction where I had previously had fairly poor results. Another missing area is south east into the Alps and central Europe. I hope that someone is listening up there and can organise one in that direction next.

73 Jim

GM4FVM

New countries worked and DX records reached on aurora recently - thanks to Q65

I have posted before about me using Q65 for auroral propagation. If you need to, you can read about that here. However, this current post is about how much better I have been doing in more recent soar events.

There were two auroral openings here a few weeks ago (4 and 12 August) which I should perhaps have reported on at the time. Well, I had a rough posting in the works but it never got much further. 

Believe it or not I do have to lead a more or less "normal" life outside amateur radio. Sometimes I have to do things like replace 35 kitchen doors and drawer fronts using the skills I learned from "Squarehole". He was my woodwork teacher during our tempestuous time together back in 1968. Would it have helped if I had listened to him? Probably not. It might have helped if he had listened to me from time to time. There is only so far you can go with wooden tea pot stands when you future life is more diverse.

Ah well.

GM4PMK's magnetometer on 12 August 2024

As per usual, click to enlarge the images if necessary.

Anyway, those solar events produced contacts with countries which I have never reached by aurora before. Take for example OH6KTL on 144MHz, my first auroral contact with Finland on that band. I worked Lasse on both events. OK, I have worked Finland on 2m before, on meteor and ionoscatter, plus tropo, so what difference does it make using aurora? Simply that unless we know what propagation method we are using we will not learn anything about propagation. Remember I have this old fashioned idea that amateur radio should be about learning. Woodworking classes should also be about learning, even in 1968, but we will have to let that thought go. Not that I am bitter or anything.

At 1504km the OH6KTL contact is the best DX I have ever worked on 2m Aurora. Also on 4 August I worked OH2BYJ on 70MHz at 1571km, which was my best DX on aurora on that band too. The contact with OH2BYJ is in fact the best DX I have ever worked on aurora on any band.

An aurora almost a mystical event. Radio auroras produce the oddest conditions with roaring band noise, strong distorted signals and dramatic changes in conditions. If the polarity of the matter reaching the Earth reverses then the radio aurora can start or end abruptly. There is also the possible bonus of Auroral Es propagation at the end of an event, but this not so common. We may get two or three days warning of an aurora, or we may not. The feeling in the shack here is of witnessing a remarkable event. So the further I can reach during an aurora extends the majesty of the whole thing.

On 4 April I worked F1FPL on 2m for a new country on aurora. I had never even heard a French station from here on aurora on any band.

Auroral contacts at GM4FVM, all bands, 4 and 12 August 2024

It is not just 2m where I have been doing well. I have been working quite a few stations during 6m and 4m auroras. However, there is no doubt that 2m has shown the greatest benefit lately.

So what might have changed which makes for greater success? Obviously every event is different but over time I can average that out. I am doing better now. 

It appears to be largely down to my use of Q65. My hearing has never been good at picking out either SSB or CW during an aurora. As the distorting effect of the Doppler shift is worse for higher frequencies, that made me shy away from 2m during auroras. Q65 has lifted that barrier and allows me to spend time on 144MHz.

70MHz auroral contact with OH2BYJ on 4 August 2024

When it came to the contact with OH2BYJ on 4 August I could hear nothing but noise on the loudspeaker and see nothing on the waterfall. I could never have made this contact any other way simply because I could not hear him.

It is not just the removal of my hearing from the scene which helps. It is pretty clear to me that using Q65 is very effective. I am working further afield, reaching more stations and filling in some gaps. I recall receiving stations on SSB who were strong but I simply could not decode any modulation in them. Q65 seems to be able to reach those ones too.

In the past, auroral openings for me (especially on 2m) tended to be limited to within these islands with the occasional LA or OZ. Now the field is opening up for me to reach further. This can only be regarded as a victory for Joe Taylor and his team. I doubt if they had me in mind when they created Q65, but it certainly works for me.

Nothing that I say should be taken to suggest that we should not use CW or SSB during auroras. That is our choice. All I am saying is how effective Q65 has been for me. During the 12 August opening I was happy to work GI4SNA and GM4CXM on 70MHz SSB. Those were very pleasant contacts and let us keep that option open. However, they are examples of the shorter range contacts I used to make. SSB does not work well for me on 2m, and CW is doubly difficult for me on that band, and the distance I could work was always relatively short.

Maybe I am odd, but I have no problem tuning around looking for signals and switching mode as I think fit. I cannot see why some people see data modes as the road to extinction of our hobby - we are not obliged to use them. We can use data for some contacts and anything we like for others (and I do).

Q65 is very adaptable, and there are a range of settings you can pick. Most stations seem to be using Q65-30C during auroras. I have tried other permutations, but that one seems to work for me. I am still happy to work stations using another other variation, but I use 30C for calling CQ.

It seems that Q65 allows me to reach further, and for others in areas not often affected by auroral propagation it allows them to reach me. Over many years I had success on this amazing propagation method but it always seemed limited, especially above 50MHz. If Q65 opens the door to more contacts during auroras then I will be very happy.

I could go further and repeat my view from previous postings. I find that Q65 is better than FT8 for contacts in any situation on all VHF and UHF bands, right up to 1296MHz which is as far as I go. The higher the frequency, the better the outcome from using Q65. I cannot really see a reason why VHF+ operators continue to use FT8 when Q65 can produce more reliable, better, DX. I also cannot see why the RSGB have a 70cm FT8 contest when a 70cm Q65 contest would produce better results.

OK, maybe at 50MHz the benefits would be less apparent, but as we go up through the bands the disadvantage of using FT8 increases. An SP station was keen to work my on 70cm tropo recently, just as I was keen to work him (I have 99 squares on that band). It had not worked on FT8 so he suggested Q65. As it happened Q65 did not work either (it is not a miracle worker) but HE suggested it to ME. Come now, this is not just my hobby-horse now. It is time for us to face reality here.

73 Jim

GM4FVM

Tracking the path of Sporadic E openings

The paths of Sporadic Es (Es) openings can often be seen to move across the Earth in regular patterns.

At one extreme, at higher frequencies we regularly get openings which only include one or two stations, and there is no movement discernible there. At other times especially at lower frequencies there is so much activity from multiple areas of Es that we cannot make out any detail out at all.

From time to time I find an opening which shows up the movement in a clear way. I have described two of these before on this blog - 

1) here, where a 50MHz opening to Japan showed an east-west pattern at the Japan end and suggested that whatever propagation method opens this path it looks very much like Es at the Japan end.

2) here, where on 144MHz the distance of the path shortened 700km over a 22 minute period.

On 6 August 2023 there was a 144MHz Es opening which showed a definite east-west transit at GM4FVM.

As luck would have it, this was a good opening with me contacting 31 stations in 103 minutes. This covered 6 countries and 18 squares, with the best DX being IK7UXW in JN80 at 2236km. On the other hand luck also dictated that I was absent from the shack for 28 minutes roughly in the middle of the event, but this did not seem to make much difference. This time the average lengths of the paths changed very little but the azimuth angle moved steadily (roughly) from "south east" to "south south east". Overall the path traced by rotator was in an arc which headed from east to west.

I have dithered a bit over how to represent this on the blog. I have plotted graphically the azimuth (my beam direction) against the time and produced a line of best fit, but somehow the graph does not show how the Es shifted very well. 

So what I have done is to show the map of the contacts with a text box showing how the front of the contacts moved across, expressed in terms of time and azimuth. The azimuth (my rotator angle) is at the top, and the time that contact occurred is below. The azimuth figures were calculated from the locators of the stations I worked.

144MHz Es contacts at GM4FVM on 6 August 2024

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

I have listed the contacts in two different colours - red for the first phase, blue for the second phase, and I was out of the shack in between.

The leading edge of the contacts moved from 122 degrees at 09:22 to 156 degrees at 10:33, that is 34 degrees in 71 minutes or almost half a degree every minute. In reality it was not evenly spread and at times (especially at the start and end of the event) it was moving more quickly.

The "searchlight" of Es propagation shining on the ground was tracing a path which moved past stations at a surprisingly fast rate. Generally as it moved on contact was lost with those behind, with only the odd contact in the rear of the leading edge.

During the period I was out of the shack it did not seem to move much at all. I must go back in the log and try to work out what was happening then.

It would be easy to dismiss this as an opening into Italy and France, with one contact each in Croatia, Switzerland (with a very determined 2E0 stations adding to the fun on tropo). Looking at my normal map of an opening it just looks random. However, looking at the timings the Es path seems to be moving in an organised way.

A more conventional view of the opening on 6 August 2024

When viewed in DX Maps it is possible sometimes to see areas of high frequency refraction which appear to move between squares in a westerly direction as the day progresses. I can see a similar effect in openings such as this. What the cause is could be difficult to determine. At first it looks likely that the Sun's movement relative to the Earth might be the cause. Certainly the Sun plays a part by driving the air movements which create and organise the Es layer. Ripples in the Es layer could also be a factor. However it might be more complex that that.

I wonder if this was one event or two separate ones. The fact that the propagation did not seem to move much during around half an hour when I was not in the shack might suggest that. Also, the full picture may be hidden due to the geography. Obviously there are not many stations in the Adriatic and Tyrrhenian seas. Signals from there might have given a fuller picture. Still it looks pretty clear to me that the paths were moving steadily westwards.

Here is the summary from that first map, still with the first phase in red and the second phase in blue:-

  156        151        148         144        140        139         136        131        122       Azimuth

10:59     10:44     10:42     10:35     10:00     09:41     09:36     09:31     09:22     Time

 More research necessary.

73 Jim

GM4FVM

I saw the propagation arrive from far away

I was out on my afternoon walk when I noticed a cloud formation which suggested enhanced propagation on VHF. It was a still sunny day on 31 July with some "nuisance" cloud towards the horizon. A careful look revealed a dark grey band below the distant cloud level. I recognised this as a band of still air above the North Sea, which indicates that a temperature inversion may be underway.

I put an inch to my step, hurrying down Ayton Law, past the alpacas sunning themselves in the still air, and home where I had a look at 2m and above.

Dark grey band just above the horizon, Ayton Law, 31 July 2024

Click to enlarge images if necessary, as per.

The dark grey band can form over the North Sea when pressure is high. When it comes ashore it produces the effect known in Scotland as the "haar". When warm air passes over the sea a foggy layer of condensation forms also known as a "sea fret". The large bank of air can be very still and stable, but the entire bank can sometimes extend ashore producing very strange conditions. When the haar arrives near GM4FVM it can be seen pouring over the headland to the south, spreading down the slopes and into the valley of the Eye Water in which this station is located.

On shore the haar produces a damp fog which feels wet and yet can be surprisingly cold for something produced below warm air. On 31 July when I approached home I also noticed a cold wind which often arrives at about the same time. This feels like the output from an air conditioner, and circulates around the stable air system. The Scots word haar is derived from a Dutch word for cold. Inside the fog it can be quite dark as if enveloped in cloud as in an aircraft, and with the Sun blocked out also strangely cold. A short distance away, outside the cloud, it will be sunny, still and warm. Overall these can be a remarkable effects.

A large bank of still air over the North Sea is just what is required for tropospheric propagation. The tropo predictions had not been too hopeful for that day, showing a detached patch of enhancement north of me and then some more over on the Denmark coast. Not promising as tropo requires a continuous path.

Hepburn Tropo Chart for 18:00 on 31 July 2024.

It seemed likely that a mass of air had formed over the North Sea and this was allowing propagation. The QSOs showed two distinct paths, one to the east to to SM and OZ, and one to the south east to DL and PA.

144MHz contacts at GM4FVM on 31 July 2024

Conditions on 144MHz have been pretty awful this year, reflecting the lack of these very conditions. So it was very agreeable to be able to work 15 stations across the North Sea, and the best DX to SM7KMJ in JO66 at 947km was pretty good.

On 70cm I worked across the North Sea to OZ2ND and PA3CWS both of whom I also worked on 2m. I saw nothing  on 23cm, despite trying hard.

Haar coming ashore is fairly rare round here. This time it did not arrive on shore, well not as far inland as GM4FVM anyway. However, seeing it in the distance and feeling that cold wind on an otherwise warm day put me on alert.

Now two days later the pressure has fallen and the usual strong winds associated with a weather system coming from the West have returned. There is no possibility of still enough air over the North Sea to hold a bank of air, and the warm weather has gone. VHF conditions have returned to their usual sleep. Even the alpacas are sheltering under the trees today.

Alpacas sheltering on Ayton Law, 2 August 2024.

Most propagation enhancements arrive silently and invisibly. Actually seeing one was a bit of a surprise.

73 Jim

GM4FVM

May's bountiful gifts continue.

No, not Theresa, I mean the month of May.

I have been musing lately over the early arrival of various forms of multi-hop Es.

Three days ago I asked this question in an email:-

That is another day in May for transatlantic propagation, when in every other year apart from this one it started in early June. Will the same thing happen with the Japanese paths, which so far only occur for me in July?

And today guess what? A 6m opening to Japan.

The event kicked off with me working RO1M, 1956km away in KO59. Now that some more Russian stations are operating on 50MHz they do provide a pointer to when the band is open further East. They produce a lot of new squares too. Then I started hearing JA.

DX Maps on 50MHz at 08:27 on 29 May 2024.

This map looks pretty good but as usual these openings are often scrappy. I worked two stations JR1LZK and JA7QVI. Best DX 9164km. I also had another possible QSO which was a bit doubtful and I await confirmation. I am not complaining about working two, but I did hear a lot more.

JA on 6m in May is certainly an unusual event at GM4FVM. In fact, JA at 6m at any time is an unusual event GM4FVM.

Perhaps even more surprising was that several stations in GM were hearing a VK station later. Indeed a number of stations in these islands worked into VK. I did not even hear that station. Not that I am bitter about it of course.

Grrr.

There was a general Es opening and I was particularly busy on 70MHz:-

70MHz contacts at GM4FVM on 29 May 2024

Click image to enlarge if needed.

12 contacts on 4m in a morning is not at all shabby. Of course the best DX was to UN7MBH in LO51. That was my best DX on 70MHz so far this year at 3480km and my first contact into Asia on 4m in 2024.

The opening extended to 144MHz, though I did not manage to work any DX. I heard stations from Sweden and Kaliningrad, but neither of these produced a contact. I was heard in the Baltic and as far away as 2450km into Russia, but sadly nothing resulted. 

As I write this, the opening is still going on at 14:46. Although it has lost that initial power, it is producing good DX on 4m and 6m. Usually the double peak nature of Es means that morning openings rarely last into the afternoon, and afternoon ones rarely start in the morning. If both periods are involved the two openings are usually in different directions.

So there are you. Quite a morning. JAs on 6m in May, VK heard by almost everybody (not me), good opening on 4m and I was widely heard on 2m.

Whatever next.

73 Jim

GM4FVM

Trying to estimate the length of the Sporadic E (Es) season and calculate the "lag".

I have recently been criticising some others for taking a few bits of evidence related to amateur radio and then building that up into a theory of Sporadic E. In my view this does not have credibility.

I am about to do something similar so this needs some qualification. I have been looking through my log book. This is obviously limited by loads of factors, but it still might be worth a look. There are 13859 entries in there, not the five data points which one of the other theorists used. Not that I have made 13859 contacts since I arrived at this location in 2009. Oh no, there are more than that. I am not legally required to log all my contacts, and a lot of local ones were not logged. That was in the olden days when there were local stations to work.

None of the missed log entries should matter for this purpose, as I have been very careful to log all my Es contacts. However, this is an early warning that we need to be aware of the many possible areas of bias in the data.

OK, I looked at the Es contacts at GM4FVM on 50MHz from 2011 to 2023. I arbitrarily excluded contacts from early December through to February to exclude "Winter Es" or "Christmas Es" or whatever you want to call that. This first measure was for the length of the season between the first contact and the last, not counting how many contacts resulted in any day or week. This method does not identify the peak of the season in terms of contacts, nor log periods with specific openings such as mini-seasonal paths to Japan or links to TEP. However, every Es contact in the log counted for this purpose including those specific ones. The data was aggregated up from activity days into activity weeks to make the maths practical.

I expected that the "lag" means that Es started later in the year and ended later in the year than a strict correspondence to the Midsummer Day (by which I mean 21 June -ish). I had expected to find that the seasons tend to be roughly the same length each year, just all shifted towards the end of the year.

Sporadic E contacts at GM4FVM 2011 to 2023 (1)

As usual, click if you wish to see an enlarged version of the images.

First of all, you can see the lag. It is about 4 weeks in the first period rising to about 5.5 weeks later. Es starts later than the Spring Equinox and now ends after the Autumn Equinox. So the data (as far as it goes) backs up my initial hunch.

Secondly, and unexpectedly, the Es season appears to be getting longer. The data seemed to fall into three distinct periods. That averages fell very close in each year within each four year period, and then there was a sharp step up to the later period each time. There were three distinct periods standing out from the statistics.

I really doubt that the period of enhanced propagation really is getting longer. I reckon it just looks like that. This finding took me back into my log for some explanation of what is happening. During the 2011 to 2014 period I was mostly using SSB ("pre data period"). During 2015 to 2018 I was using mostly PSK, JT65 and some JT9. Although FT8 was appearing not many people were using it (so this was the "PSK+JT period"). During 2019 to 2023 FT8 was in full swing and lots of people were using it ("FT8 period").

I may be wrong here, but I think that what appears to be a longer season is largely down to me switching from SSB via PSK and JT into FT8. During the SSB period I had to search out stations as they were spread throughout the band. During the PSK+JT period it was either the same spread (PSK) or I was using modes with long periods (JT65) or few followers (JT9). The sensitivity would have been higher than with SSB, but those modes did not have wide acceptance. Then during the FT8 period lots of stations appeared on the same frequency and the mode was even more sensitive. This is my theory about this; just my idea.

Working stations on Es on 50MHz has become easier over those years. More people are doing it, and that also contributes to what looks like a longer season. I doubt if the propagation has changed even though it looks like it has. It is easier to work people now because while at the start of my time on 6m stations had to have transverters, and build their own antennas, these days they have ready made equipment. Data modes have become much easier to use, computers have become cheaper and faster. Also we no longer need lossy data interfaces but we can now pass digital audio in our radios via USB plugs. As it gets easier, more stations come on looking for DX, and the season appears to extend as marginal propagation gets exploited.

Now that I had the basic information that it is indeed shifted to later in the year, I started thinking about the "shape" of the season. It feels to me that once the main season starts, usually about 4 weeks after the first contact, it suddenly bursts forth and reaches a quick peak, and then subsides gradually until the end.

So how to find where the peak is? My data measured so far is just contacts spread over time. It does not show when the main burst of activity happens. I could only do this on 50MHz by going over every contact individually - which I might do some day but not right now. There are thousands of them. So what might measure the timing of the peak? It dawned on me that my 2m Es contacts usually only happen at the peak.

I make the usual pre-condition that these are just my own data, and sometimes I am away, not watching 2m, or something similar. I spent a lot of my early years here thinking that 2m Es was rarely possible from this far north. Would there be enough data? Well, just like on 6m, the spread of data modes has provided me with a lot more data than I thought I had - 31 data points. There are bound to be fewer as these probably represent the peak of the Es propagation each year.

I then calculated those days from first to last contact and put them on the same graph:-

Sporadic E contacts at GM4FVM 2011 to 2023 (2)

The 2m contacts were almost symmetrically spaced on either side of midsummer. Unlike the 6m contacts where the lag was at least 4 weeks, the lag at 2m was almost zero (less than 12 hours) and not statistically significant.

This suggests to me that my second hunch that the Es peak comes in a rush towards the start of the season is also right at this station. However, just as on 6m, my figures just show when the 2m contacts happened not how big the opening might be on that day. Such figures on the "bigness" of an opening can be very misleading, as openings to my west are never big because there is just the Atlantic Ocean in that direction. 2m Es openings almost never include multi-hop Es, or not from here anyway, and nor have I noted them linking to TEP (not YET!!!). So the subjective quality of an opening is not something that I have tried to measure. But still, if the 2m contacts do indeed represent the peak of Es propagation then the peak here does not appear to lag behind the midsummer like the rest of the season does.

Now I want to go further into speculation. What might the shape of the Es season look like if I could work out the "bigness" of openings? Well, here is the FVM conjecture. I suggest that it looks like a gamma graph something like this one:-

Gamma distribution.

With apologies to whoever drew this, I cannot give an attribution as I cannot find where it came from via the internet. Let me know if it is yours; meanwhile I will try to find a better one. I am using it as x along the bottom axis looks like months of the Es season, and f(x) could be the "FVM-Es-bigness scale" [now you are getting carried away Jim].

Anyway, if this is roughly the shape of the season it would fit with the pre-data mode earlier years simply sampling the top part of the graph, say above f(x) = 0.3, and then as we got more sensitive modes and more activity we are sampling further down the vertical axis and finding the tail on the right. Thus the lag seems to be getting later and the season longer, which is what I found. 

Warning: This is just one guy's log history. It is not very reliable. I could do more and better statistical analysis but that would expose the unreliability of using any amateur's data. So it is not scientific, and no ham survey ever will be. Despite this I think it does provide something to think about.

When I was at college there was a lot of enthusiasm for using "qualitative" data. That is not gold standard statistically but it does show trends. What I have tried to do here is show what I have found in a qualitative way. It is up to you whether you believe it or not. For me, however, it has "face validity". It seems to explain what I have been seeing over the years.

First thing I can see is that the lag on 6m pretty well rules out Es linking into TEP in the Spring from here, but would suggest that is more likely in the Autumn. A quick check suggests in my case that Es linking is at least 9 times more likely to happen in Autumn. Secondly, I had better not rely on the lag to look for 2m Es contacts later in the year, as they seem to be equally spaced around midsummer. I will miss them if I wait. And thirdly, whatever the reason, it is worth hanging on looking for 6m Es right into the tail of the season, certainly in October and even later.

This works for me, and I hope it sheds some light on the Es season in some way for others.

73 Jim

GM4FVM