Geoff, G0LUJ, was in touch with me following my posting about Es predictions. Geoff too has been disappointed by the predictions he has seen.
I have to agree there. What I see passing for predictions are often useless, though I can well imagine that trying to predict propagation might be a fairly tricky task, especially at VHF.
In outlining the link I find between Es and X-Ray bursts I was thinking about understanding the process rather than making predictions, though of course these are related. Geoff raises a good point by saying he was going to try to look for some chance of predicting events. The X-Rays travel from the Sun at the speed of light, and those little bursts I see will be here are soon as they are detected ... almost. The GOES satellites give us some advantage, and then there seems to be an hour or maybe up to two hours delay before the Es occurs. But the link is clear for me to see.
I have seen over 100 WSPR spots on 10 metres after such X-Ray bursts in the past week. Stations regularly featuring include IK1WVQ, IU1DZZ, DK6UG, DB0ZDF, DK1RS, HA9AL - all within a single Es hop. I am not so sure about SV8RV, as he has appeared several times and that is probably a double hop - unusual in Winter (I think). I said I was not going to go on about this apparent linkage, and I won't, but it is interesting for February.
There were also a couple of spots after another feature which seems to be linked - a rise in the Solar-K index short of an aurora. In this case it was K=3 and there was no aurora here. This though may be the often noted "auroral Es" phenomenon which is very welcome but something else. It usually only benefits Northern stations, unlike the other ones which were south of me.
And so, leaving Es predictions aside for a while, I wanted to think more about when I hear Es rather than when it happens. Eh? Well Gianfrance, IU1DZZ, pointed out to me (about "Sporadic E") ..
it's just a conventional name. Not sporadic. It's frequent, but often
it appears in wrong places for us, or it lasts only few minutes...
That really made me think. Yes, I can see Es almost everyday on DXMaps. But I don't hear it every day. What does this mean? Well, we know that Es is very localised from the viewpoint of the individual ham. From the viewpoint of stations I might work - the DXMaps page "Europe" - it happens pretty well every day on 10m. So, when I see an X-Ray pulse on SolarHam and I look for Es, I have been finding it because the Es cloud just happened to fall between me and Gianfranco and those other helpful stations. But sometimes it must happen and I do not hear it. So what are the probabilities and how can we predict that?
There are a lot of variables here, but I know somewhere else where several unknown variables have been combined into a useful model. Whether a similar model will ever predict anything useful about Es I do not know, but please let me take us down this route.
The model I am thinking of is The Drake Equation. In 1961 Frank Drake was working on a model which would allow us to think about (not necessarily predict) the probable number of extraterrestrial civilisations who might just contact us. This will of course depend on how many of those civilisations there are (which will depend on the number of planets, which would depend on the number of stars and galaxies), but also on what stage of development they might be at and whether they can communicate with us ... etc !!!
Wikipedia says this ..
The Drake equation is a probabilistic argument used to arrive at an estimate of the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The number of such civilizations, N, is assumed to be equal to the mathematical product of (i) the average rate of star formation, R*, in our galaxy, (ii) the fraction of formed stars, fp, that have planets, (iii) the average number of planets per star that has planets, ne, that can potentially support life, (iv) the fraction of those planets, fl, that actually develop life, (v) the fraction of planets bearing life on which intelligent, civilized life, fi, has developed, (vi) the fraction of these civilizations that have developed communications, fc, i.e., technologies that release detectable signs into space, and (vii) the length of time, L, over which such civilizations release detectable signals, for a combined expression of:
I am no Frank Drake. I do not have the intellectual ability to even really understand what he has proposed, but I get the general idea. I think his approach could be applied to understanding (but not necessarily predicting) Es.
In 1961 Frank Drake was not really proposing to put actual numbers into the elements of the equation, he was outlining the broad parameters which would apply. Estimates could be made or not, but at least you were considering what factors to include. Since then of course, we have found that almost every star we look at has several planets, so we are beginning to get some feel for the likely numbers.
This is a bit off the track of Es predictions. Still, what I was thinking about is, what are the factors we would need to take into account to see whether Es would occur HERE (GM4FVM, on a band I listen to, at IO85, when I am awake ...)
So without the equation actually being written at the moment, what factors arise?
Well the probability of Es being heard by me will depend on (at least):-
1) time of day and time of year
2) the formation of ionisation in the Es layer, which in turn would depend on:-
- energy from the Sun (for example solar heating of the atmosphere [perhaps mostly UV] but also transient bursts such as X-Ray and proton bursts)
- solar wind as in auroral Es (speed and density being factors?)
3) location of the ionisation cloud
- within the arc which brings a possibility of a contact here, or elsewhere (distance and direction)
- in relation to countries which have amateur allocations in the band in question
4) the probability of there being an amateur within the suitable region (operating, operating on the same band, with suitable antennas pointing the right way, ...)
I have not formed this up into an equation as I think it is fine like this while I ponder over it.
I have not even considered "double hop", where you have to have two Es clouds and that brings in some very complex geometry and probabilities.
One of the major questions is not "is there Es now?" but "is there Es somewhere where I can make use of it"? Gianfranco is right - there is always Es.
As I said earlier, there is Es a lot of the time. Often, the position of the Earth on its rotation means that is overnight here, and Es is benefiting amateurs on the other side of the world. However, a lot of Es in Europe is not going to benefit me either. Only Es clouds located in a wide arc around 600 - 1000km round my location from about 60 degrees to about 200 degrees ever produce much Es here.
If they are too close I can see EIs working stations on the cluster. If they are too far away I see Russian broadcast stations being received in Sweden. If there is Es in the other 220 degrees I rarely even know about it. Yes, I have worked Jan Mayen, Iceland, Newfoundland, Azores and so forth, but those are specks of land in those directions with almost no amateurs. There are vast swathes of Atlantic Ocean with no stations within Es range. Russia does not have 6m, Switzerland does not have 4m, Africa has very few amateurs these days and even fewer on "my" bands ... the list of blank spots around me multiplies all the time. There must be an awful lot of Es which I can never detect.
Here is the point. Predicting Es is not really the key to this. It is possible to predict Es more or less every day. Predicting where the Es clouds will occur is the art. Will they occur somewhere which allows me to make a contact? Will there be anyone there even if the band does open?
By some strange quirk, doubling the number of amateurs, especially in certain parts of the world and certain bands, would produce a lot more reports of Es, though the actual occurrence of the phenomenon would not have changed.
Please excuse this flight of fancy. I think it might take us somewhere in understanding the prevalence of Es. Until we realise that the factors affecting us hearing Es are different from those deciding how much Es there might be, we will never understand it. Just as Frank Drake tried to tease out - there may or may not be a life form out there, but whether we ever contact them depends on a lot of other variables.
On the other hand, there may be no intelligent communicating life forms beyond the Earth at all - which is what I believe. Proving it is a bit more difficult.
Mind you, I seem to hear some Aliens on the bands sometimes.
P.S. I am an Alien here in Scotland - I was not even born here.