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Blog readers may remember my previous blog discussing a more optimistic prognosis for the just-starting solar Cycle 25. It described the then recently-published scientific paper whose conclusion was rather startling:

 

 

 "... we deduce that Sunspot Cycle 25 could have a magnitude that rivals the top few since records began."

The scientific paper described the exact opposite of any and all predictions that I have read or have seen referenced, and at the time of publication, was surely a bold and risky claim for the paper's authors. (1)

An over-simplification of the methodologies used to develop their prediction describes the study of the complex relationship involving the Sun's 22-year (Hale) magnetic cycle, the end points of adjoining cycles called 'terminations' and sunspot production, to predict the eventual strength of the new cycle.

The end of the cycle or ‘terminator’ event plays a significant role in the new cycle’s progress, as the shorter the separation between adjoining terminators, the stronger the next cycle will be. The possibilities of Cycle 25 being a truly strong one depends upon (according to the paper) a terminator event occuring sometime before the end of 2020.

Although there has been no official announcement as of yet, it appears that the termination may be presently occuring. Again following the paper, the termination event will produce a sudden and marked upturn in the growth of solar activity and will in fact, switch on suddenly within one solar rotation. As startling as this sounds, it appears to be exactly what is happening on the Sun right now.

 

courtesy: nasa.gov

Just one week ago, the Sun’s solar flux stood at ~79 sfu (Solar Flux Units) but has climbed rapidly to 110. With several active sunspot regions on the earth-facing side of the Sun and several actively flaring groups about to rotate into view on the backside, it seems as if this sudden growth may be sustainable.

What is particularly encouraging is the activity level of the earth-side spots as well as the ones coming around, with several C and B-class flares continuing to push the flux higher. 

Although it will likely slow and subside, a key indicator of future strength will be the time that it takes to recover and climb again. 

Another interesting gauge of a new cycle’s possible future strength is the number of months needed to reach an average monthly SFI of ‘90’. Strong cycles tend to climb early and rapidly, in order to reach their lofty heights. 

The strongest cycle on record was Cycle 19, the grandaddy of them all. 

courtesy: http://www.solen.info/solar/

 

Compared to anything before or after, it was a magnificent monster of a cycle for ham radio. Cycle 19 reached the magic SFI 90 value in only 18 months ... Cycle 25 has reached this same point in just 12 months! If this is indeed an accurate marker for cycle strength, and there is no reason to believe otherwise, then maybe we should all hold onto our hats.

We’ve been told for several years by those who know these things, that Cycle 25 would likely be a repeat of the poorly-performing Cycle 24, or even weaker. I think one thing  that can now be reasonably surmised is that this isn't another Cycle 24! We should know shortly, if Cycle 25 is the real thing or not, once the termination event has been confirmed.

In the meantime, enjoy the wide open strong signal opportunities now playing on 10m ... the band is back once again and in fine form ... way earlier than anyone ever expected!

 

 (1) Scott W. McIntosh (1), Sandra C. Chapman (2), Robert J. Leamon (3,4), Ricky Egeland (1), and Nicholas W. Watkins (2,5,6)

1 National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, USA.
2 Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL, UK
3 University of Maryland, Department of Astronomy, College Park, MD 20742, USA.
4 NASA Goddard Space Flight Center, Code 672, Greenbelt, MD 20771, USA.
5 Centre for the Analysis of Time Series, London School of Economics and Political Science, London WC2A 2AZ, UK 
6 School of Engineering and Innovation, STEM Faculty, The Open University, Milton Keynes, UK

Unlike most forecasts for solar Cycle 25, a recently released paper from five solar scientists (1) has given many 6m diehards new reasons to hope!

After countless dire predictions for the upcoming cycle indicating similar or even poorer activity levels than the disappointing Cycle 24, the new paper suggests just the opposite!


In fact, the group of scientists predict that "Cycle 25 will probably be among the strongest solar cycles ever observed, and that it will almost certainly be stronger than present SC24 (116 spots) and most likely stronger than the previous cycle 23 (180 spots)." The possibility of a smoothed sunspot number (SSN) reaching as high as 305 is in the prediction!

Solar Cycle 19 was a monster, reaching a SSN level of 285 ... to imagine the possibility of something even stronger is truly exciting. The just-ending Cycle 24 was one of the weakest on record, reaching an SSN of just 116.

Will Cycle 25 replace Cycle 19 as #1? Image source with my addition in RED.

During Cycle 24, maximum usable frequencies (MUF) for F2 propagation often struggled just to reach 28MHz, and except for the peak year, the worldwide propagation conditions that amateurs had come to expect were often absent.

Should these new optimistic predictions come to pass, 6m operators can look forward to some truly, never-before-seen, fall and winter propagation ... for at least three or more winters.

With SSN values reaching the high two-hundreds or beyond, west coast operators can expect to see the 6m band often open before sunrise, most likely favoring Europe via the polar path or towards Africa via the trans-Atlantic path. Unlike 20m, there will be little to no ‘polar flutter’ and since signals propagating near the F2 MUF suffer very little path loss, they will probably be very strong.

Later in the day, propagation will shift south towards Central and South America before moving to the west. Depending on the time of year, the propagation will favor Asia, with signals from Japan, China and other far-eastern exotica in the early fall through the New Year. As well, the band will often stay open for some time after local sunset. Late winter and spring will see the western path favour signals from down under, and stretch out to the southern far east regions towards the Indian Ocean. These were the propagation patterns noted from here during Cycles 21-23, when SSNs reached 233, 214 and 180 respectively.

With much gratitude to Mark (VA7MM) for converting my old analog tapes to mp3, here is a recording I made on the morning of November 7, 1979, at the height of Cycle 21. It will give you a taste of what could be in store. On that Wednesday morning, the band opened around 0800 and continued through to sunset, closing with a three-hour opening to the Pacific and Japan. Like many other 6m operators, I had taken the day off work with a case of the 'F2 flu' that was very prevalent that winter! The recording begins with a short exchange between VE1ASJ and VE1AVX, while trying to work their first KL7 ...

F2 from Cycle 21

The graph of Cycle 21 shows when the recording was made. Although not known at the time, it was very close to the peak of the cycle.

courtesy: http://www.solen.info/solar/

courtesy: http://www.solen.info/solar/

A record-busting Cycle 25 will be like these previous cycles only on steroids! With such a cycle, 10m will follow a similar pattern but will likely be open 24/7 as I recall listening to VKs and ZLs on 10m AM well after midnight during the downward climb of Cycle 19 ... and this was on a very '10m-deaf' Hallicrafters S-38 and a short wire out the attic window!

For those wanting to read the fascinating paper (Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude), you can find a pdf here. As well, you can read the ARRL’s own announcement of this exciting possibility here.

One certainty is, that if FT8 is still around by then, it and your soundcard will fold up quickly once the band opens with wall-to-wall S9++ signals. It may be useful during the first early minutes or during marginal openings, but knowing the signal levels that 6m F2 can produce, it will be like trying to use FT8 with dozens of new neighbors operating on your own block ... and you can easily guess how well that might work! As we’ve come to understand, FT8 is a wonderful weak-signal mode, but throw just one bone-crushing signal into the waterfall and it’s game-over ... on F2, there will be dozens of these!

Such stellar conditions on 6m are ideally suited to CW or SSB and I think there will be a fast exodus from FT8 back to the traditional modes very early ... those that aren’t prepared for this, relying only on FT8, will most likely be in for a rude awakening. If you’re a 6m “no-coder”, now’s the time to hunker-down and learn CW ... by the time Cycle 25 becomes productive, you won’t be left out of the many CW DX opportunities that will surely be available on this much quicker QSO mode.


We will no doubt be reading more about this as Cycle 25 begins to grow. As in almost all stronger than normal cycles, growth from the start to the peak is much shorter than normal so I’ll be watching for a fast rise in sunspot numbers once we are really underway.



Hindcast modelling (backtesting) of the data derived from previous cycles going back to the 1700s using the paper’s prediction methodology, shows an accurate alignment with what actually occurred. The red dots in the graph above indicate the model’s predicted peak superimposed on the actual peak. In some cases, the peaks were even higher than the modelling suggested.

The predictions identify the so-called “termination” events, landmarks marking the start and end of sunspot and magnetic activity cycles, extracting a relationship between the temporal spacing of terminators and the magnitude of sunspot cycles. The success of these predictions will depend upon an upcoming terminator event before the end of 2020. Should it occur on time, the predictions will be given a much greater chance of coming to fruition ... "with a terminator event in 2020, we deduce that sunspot cycle 25 will have a magnitude that rivals the top few since records began. This outcome would be in stark contrast to the community consensus estimate of sunspot cycle 25 magnitude."

More interesting discussions of the paper can be found here and here.

This week's high-latitude Cycle 25 sunspots are a great sign. When the terminator event occurs, solar activity will ramp-up very quickly, within one 27 day solar rotation. Let's hope we're getting close.


As noted in the paper, "Very early indications of the spot pattern are appearing at higher than average latitudes. Historically, high latitude spot emergence has been associated with the development of large amplitude sunspot cycles — only time will tell."

Hopefully we’ll all need to hold on to our hats ... it just might just be the ride of our lives!



(1) Scott W. McIntosh (1), Sandra C. Chapman (2), Robert J. Leamon (3,4), Ricky Egeland (1), and Nicholas W. Watkins (2,5,6)

1 National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, USA.
2 Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL, UK
3 University of Maryland, Department of Astronomy, College Park, MD 20742, USA.
4 NASA Goddard Space Flight Center, Code 672, Greenbelt, MD 20771, USA.
5 Centre for the Analysis of Time Series, London School of Economics and Political Science, London WC2A 2AZ, UK 
6 School of Engineering and Innovation, STEM Faculty, The Open University, Milton Keynes, UK

The batch of bureau cards last week included several cards from Europe and were probably the last I'll get for my Cycle 24 10m fun, using the homebrew Tri-Tet-Ten.


As mentioned previously, this rig was the culmination of wondering, for many many years, if I could get a single 6L6 to work well enough on 10m CW, using a 40m crystal ... quadrupling to 10m ... and still have enough useful output to work Europe! As well, the note would have to be 'acceptable' as I realized that any crystal chirping would be multiplied four times, during the quadrupling process.



The evolution of my eventual transmitter, is described in more detail here, where you can also hear what the tone sounds like. Suffice to say, the results were much more than I had ever hoped for and during the peak years of this past cycle, many enjoyable hours were spent on 10m CW with my one tube tri-tet crystal oscillator.

I guess I could always move down to 20m CW but, for me, this just doesn't have the same appeal or sense of satisfaction as using it on 10m or what I like to call, "the other magic band". Who knows what Cycle 25 will bring to 10m? I may get another chance yet, if the solar prognosticators are all wrong!