Sporadic E and geomagnetic storming.

This is what Solarham (see sidebar for a link) stated:-

"Geomagnetic Field and Aurora - Past 24 hours : Storm."

This suggests to me that an aurora is possible though there was no enhanced propagation of that type noted at GM4FVM. There were however some auroral contacts by stations to the east of me.

This is what I have termed in the past a "geomagnetic disturbance short of an aurora". And frankly these are the ones I am really interested in.

What there was turned out to be a lot of Sporadic E propagation.

Once again this posting is about the close correlation between disturbed solar conditions and enhanced Sporadic E events. I say "once again" as that was the theme behind eleven postings on this site dating back to 2015. You cannot say I have not been banging the drum about the fact that I use sites like Solarham, NOAA and NASA to predict likely Es openings, and then I switch to the magnetometers of the Norwegian stack, GM4PMK and STEREO to monitor the events as they unfold (links in sidebar). 

One of these postings, in 2017, was titled "Using aurora warnings to predict Es". I think it is clear what I am doing. Meanwhile my national society the RSGB continues to bleat on about Jet Streams and make predictions based on terrestrial weather which simply miss entire events.

Therefore you may already have noted that for years and years I have been pointing out that Es is often to found when there is geomagnetic disturbance. You may already be bored by this. Still, here I go again with an even bigger and more conspicuous set of events.

During the peak Es season, say in June, it is not easy for me to see the link because there is just too much Es around which may hide the opening. On the other hand during the least Es activity, say during February, increased activity on the Sun may not open a band which is firmly closed. 

As radio amateurs what we are hoping for at other times is for enough energy to be imparted to "push the ionosphere into producing a Sporadic E opening". My words.

I often see these openings most clearly during the shoulders of the season. April and early May plus late August and September. That is when I believe that geomagnetic storms show that they can produce unexpected Es. At other times it is no so clear but I have posted occasions when I noted that it happened.

There was no Es worked here between 11 August and 17 August. No Sporadic E here at all for a week. The Es season seemed well and truly over.

Then on 18 August a geomagnetic storm reached us, which in my book indicates that Es may be just around the corner. Solarham had issued a warning well in advance.

It is difficult to work out which day the results of the coronal mass ejection might arrive and a second event warning was issued the following day - actually a multi-event warning.

So there were in fact several events on the sun which sent mass ejections earthwards. They generally pass first with a shockwave and then later with a geomagnetic storm which I believe set off the Sporadic E events.

The following image from the GM4PMK magnetometer show the first storm followed by the second shockwave.

GM4PMK magnetometer readings for 18 August 2022

What I would have expected during a period when the planetary index reached K5 as seen here would be an Es event. And here it is as seen at GM4FVM:-

50MHz contacts at GM4FVM on 18 August 2022

My first contact was at 13:09 but it really started to hot up at 19:05 and continued to 20:23. 9H1TX was a new DXCC on 50MHz and a new square for me. After the shockwave I decided to pack it in as that seemed to have ended the event, but I expected things to carry on the next day, which turned out to be the case.

I started on the 19th at 06:00 and the contacts continued until 09:47.

Here is the map of contacts on 6m for both days:-

50MHz contacts at GM4FVM on 18 and 19 August 2022

So in a period less than 24 hours I worked 43 stations on 6m, in 36 squares and 14DXCC. ODX was SV3AUW in KM17 at 2770km.

The PMK magnetometer did not show much effect on 19th but the ionisation from the previous day seemed to continue. Perhaps one of the clearest signals of what what happening was given by Solarham which showed the planetary index at K5 coinciding with the times of the opening.

Solarham storm warning and K index on 17 to 19 August.

It seems to me that Sporadic E openings like this are more likely to be related to geomagnetic storm conditions than purely to the K number. Of course those two are closely related but from what I have observed disturbed conditions seem more likely to produce Es than even strong but steady streams heading from the Sun. The proton and X-ray recordings also seem very reliable indicators of useful events on the horizon, as shown in previous postings.

So what causes Sporadic E?

Nobody really knows.

The ARRL handbook refers to possible metallic particles in the E layer and to wind shear. It seems likely to me that the particles become ionised under the influence of solar streams and form a layer located by the Earth's magnetic field. Once suspended it seems inevitable that movements in the atmosphere below the fixed layer (wind shear) will organise and enhance the layer. That is what I make of the ARRL handbook's explanation and it seems to make sense to me.

Reference to metallic particles is sometimes linked in the literature to these molecules having their origin in meteors. This theory does not relate to the ionisation created when we amateurs use scatter propagation during meteor showers. There appears to be no link between meteor showers and Sporadic E. The particles possibly implicated in Es are likely to be from the random accretion of material by the Earth which becomes ionised and formed into the E layer by the processes set in train by the geomagnetic disturbance. That is if meteoric material is involved at all - this seems to be speculation (like so much about Es).

During the peak Summer season there is enough ionisation in the ordinary course of events produced by UV and other radiation for openings to occur regularly. I see a pattern that during the Autumn and Spring geomagnetic disturbances can produce enough additional ionisation to cause periodic openings when otherwise things are quiet.

And as predicted on Solarham  on 17 August, the arrival of several solar steams over a number of days was likely to produce several openings as this table shows:-

Solarham forecast for 3 days plus results for previous days.

The pattern of raised K number shows a close correlation with my log book. Es occurred when the K level rose to 4 or 5.

I cannot continue to report on the events of these repeated disturbances so I will summarise the four days up to the end of play on 21 August. During those four days I completed 100 QSOs into 25 DXCC and 72 squares, compared to the previous four days when the total was zero. That was just on 6m, I worked some on 4m too. Before that there was a week with no Es here. Once the event is over, be it today or another day, no doubt there will be a week with no Es, and geomagnetic activity will eventually subside. In my mind that means 6m Es is closely related to geomagnetic activity.

I have been posting about these openings being related to geomagnetic disturbances on this blog for years. It has stopped surprising me and now I use the signs as predictors. I do not use the other much touted "predictions" produced by the great and good of our hobby, largely because I find that they do not work.

I believe that Sporadic E is caused by a combination of many factors so a simple explanation may never be found. This mechanism seems to have some effect, but I am pretty sure that it is only part of the story. However, I cannot ignore the coincidence of these events and this result:-

50MHz contacts at GM4FVM 18 to 21 August 2022

It is not certain exactly how this works, so I just accept that it does. However, one thing I am pretty sure of. Earth wind systems such as the Jet Stream seem to have no relation to Es openings as seen from GM4FVM. I have looked into the Jet Stream theory for a long time and whilst there may be some connection it looks to me that Jet Streams have no "cause and effect" relationship with Es and have no part to play in their predictability. On the other hand, I got the first warning of these openings on 14 August. That satisfies me that, at least in Spring and Autumn, keeping a watch on disturbed solar conditions is a good guide to finding Sporadic E openings.

73

Jim

GM4FVM and Aurora