SC25 Progress Update - 02/11/23 on Youtube

[Scott McIntosh]

Dear All, I recorded this solar cycle 25 update this past weekend. Enjoy. Happy to answer questions that may come up.

[hamateur 1953]

Really great presentation Scott!! 

[hamateur 1953]

Its a long way to the top ifya play the pipes…..

[Drax Spacex]

Hi Scott,

Great presentation - I enjoy your casual diction and the occasional "colorful metaphor" - atypical of most technical presentations but eminently more enjoyable!

This is my first experience of solar maxima as a ham, and I have, as many others, indeed noticed empirically the incremental improvements in propagation with higher and higher SFI.  6m not popping yet, but 10m absolutely is.  Daytime Maximum Usable Frequency (MUF) from Boulder, CO is regularly above 30MHz.

From my guessimate, it looks like the solar maxima phase typically lasts about 3.5 years, over which time there may be a single peak or double peak (averaged).  It would be useful to know whether after the first peak we should expect another peak a year or two later, or if "the show is over."

My question - at 48:00 on the SC25 Maxima Timing slide, bullet 3 tantalizingly says "Indications that there will be strong hemispheric synchronization.  Possibly a single peak for SC25."  Can you please elaborate on these indications - i.e. what is predictive of a single or a double peak?

Thanks!

[Sam Warfel]

10 hours ago, Drax Spacex said:

My question - at 48:00 on the SC25 Maxima Timing slide, bullet 3 tantalizingly says "Indications that there will be strong hemispheric synchronization.  Possibly a single peak for SC25."  Can you please elaborate on these indications - i.e. what is predictive of a single or a double peak?

Thanks!

I’d echo this question as well.

[Philalethes]

22 hours ago, Drax Spacex said:

My question - at 48:00 on the SC25 Maxima Timing slide, bullet 3 tantalizingly says "Indications that there will be strong hemispheric synchronization.  Possibly a single peak for SC25."  Can you please elaborate on these indications - i.e. what is predictive of a single or a double peak?

12 hours ago, Sam Warfel said:

I’d echo this question as well.

Count me in on that, I'd like to hear the reasoning behind that too.

I read some papers suggesting that the presence or absence of peaks is found independently in both hemispheres, and that it's the combination of the two "waveforms" that yields either a "spike" (a single clear maximum with relatively steep ascent and descent around it), a "dip" (a single clear maximum with a plateau on either side), or the recognizable "gap" (two separate maxima); they went on to suggest that which of these would crop up was primarily determined by the presence or absence of rapid movement in the polar fields around the time of "canonical" minimum (as opposed to using anything related to the terminators), and on this basis they predicted there would a dip in the northern field, resulting in an overall dip too.

I'm still not sure if this dip was predicted to be large enough to contradict what Scott means by "strong hemispheric synchronization", or whether their ideas are compatible (after all I don't think Scott is saying anything conclusive here either), but I'd certainly be intrigued to know the train of thought being followed.

[Drax Spacex]

My guess is "hemispherical synchronization", as a predictive indicator of single or double peak, could be measured by how well the vertically mirrored N/S polar magnetic field plots match up on the way to solar maxima - though some time offset is usually expected (?).

Actually, SC23 provides a counter cherry-picking example to my above guess  - as solar maxima had a double peak yet  N/S polar magnetic field plots were fairly symmetrical and almost coincident in their zero crossings.

https://www.aanda.org/articles/aa/full_html/2018/10/aa32981-18/F1.html

Edited February 17, 2023 by Drax Spacex
uncherry-picking

[Drax Spacex]

11 hours ago, Philalethes Bythos said:

they went on to suggest that which of these would crop up was primarily determined by the presence or absence of rapid movement in the polar fields around the time of "canonical" minimum (as opposed to using anything related to the terminators), and on this basis they predicted there would a dip in the northern field, resulting in an overall dip too.

I'm still not sure if this dip was predicted to be large enough to contradict what Scott means by "strong hemispheric synchronization", or whether their ideas are compatible (after all I don't think Scott is saying anything conclusive here either), but I'd certainly be intrigued to know the train of thought being followed.

Interesting premise, that characteristics of polar field activity at minimum might be predictive of characteristics at subsequent maxima.

[arjemma]

Really interesting talk, thank you Scott!

[Philalethes]

2 hours ago, Drax Spacex said:

Interesting premise, that characteristics of polar field activity at minimum might be predictive of characteristics at subsequent maxima.

Yes, it's indeed quite interesting, albeit not a new idea by any means. As you might know, Leif Svalgaard has been writing about a polar fields model to use in that regard for decades, whereby a rough estimation for the following maximum can be predicted from looking at the polar fields at minimum. Perhaps it also ties in with Scott's data showing how shorter terminator-to-terminator cycles will be predictive of stronger maxima too. I'm not entirely sure how well Svalgaard's predictions have fared historically, but he did notably predict that SC24 would be very weak, predicting it would be the weakest in over a century with an SSN of 75 ± 8 in this paper; it did end up being very weak, but not that weak, so he wasn't quite spot on, seeing as how the SSN surpassed 100 and how SC14 and SC16 both had a comparable maximum SSN, but it's still not a bad prediction in my view. In this paper he makes a prediction for SC25:

Quote

Direct measurements of the polar magnetic fields are available since the 1970s and we have just passed the solar minimum prior to solar cycle 25, so a further test of the polar field precursor method is now possible. The predicted size of the new cycle 25 is 128±10 (on the new sunspot number version 2 scale), slightly larger than the previous cycle.

This is clearly not as high as Scott's prediction, so we'll see eventually who gets it right (but of course, given the complexity of Solar activity, one should be careful not to draw any hasty conclusions from getting a single prediction right or wrong as conclusive evidence).

[Drax Spacex]

On 2/17/2023 at 12:47 PM, Philalethes Bythos said:

In this paper he (Svalgaard) makes a prediction for SC25.

This is clearly not as high as Scott's prediction, so we'll see eventually who gets it right (but of course, given the complexity of Solar activity, one should be careful not to draw any hasty conclusions from getting a single prediction right or wrong as conclusive evidence).

Great papers.  They tie in well the use of polar magnetic field data as a common denominator in contemporary prediction methods.

Figure "38 Predictions of Solar Cycle 25" included in the Conclusions of the Svalgaard's SC25 paper is elucidating and humbling given such a large range in predictions. 
https://www.researchgate.net/figure/The-38-predictions-of-Solar-Cycle-25-that-had-been-registered-by-January-2020-Adapted_fig2_344505596

As you say, one right or wrong solar cycle prediction doesn't validate or invalidate a particular theory or method.  Regression testing of a prediction method against past solar cycles is key with the prerequisite of having available and consistent input data for previous cycles.  This can be problemmatic when polar magnetic field data is required.

There are certain solar cycles that are outliers that can "break the mold" of an otherwise robust and good performing prediction method.  SC 21 is a good example.  Its actual solar max is higher than is commonly predicted.  It shows up as an outlier in my armchair back-of-the-envelope sunspot number precursor prediction methods.  It shows up as one of the more distant data points from the regression line in Scott's results.  In Svalgaard's SC25 prediction paper, SC21 shows up close to the regression line; however there is the following caveat/disclosure:

"We do not have measurements of DM at WSO for times before the minimum in 1976, but only for just after the minimum when the fields have already begun their decline due to new flux arriving at the polar caps from lower-latitude decaying sunspots from the growing Cycle 21. Comparing the decline with similar declines for the other cycles allows us to ‘guestimate’ a likely DM for the years prior to the minimum between Cycles 20 and 21. This (somewhat uncertain) value has been entered in Table 1. "

The irrascible "wild hair" solar cycles will no doubt continue to crop up from time to time that will confound, fascinate, and/or infuriate.   But that should be expected.  To quote from the movie Prometheus, "God does not build in straight lines."

 

[3gMike]

On 2/17/2023 at 6:47 PM, Philalethes Bythos said:

In this paper he makes a prediction for SC25:

That is a really good, and credible, paper.

In searching for some further data on the 38 predictions I came across this paper on predictions for the North/South symmetry of SC25 https://link.springer.com/article/10.1007/s11207-022-01956-z Unfortunately it costs £30 to gain access to the pdf, but it certainly sounds interesting from the Abstract.

[Philalethes]

2 hours ago, Drax Spacex said:

Figure "38 Predictions of Solar Cycle 25" included in the Conclusions of the Svalgaard's SC25 paper is elucidating and humbling given such a large range in predictions. 

Citing Aristotle in an academic context like a boss.

[Drax Spacex]

7 hours ago, 3gMike said:

That is a really good, and credible, paper.

In searching for some further data on the 38 predictions I came across this paper on predictions for the North/South symmetry of SC25 https://link.springer.com/article/10.1007/s11207-022-01956-z Unfortunately it costs £30 to gain access to the pdf, but it certainly sounds interesting from the Abstract.

This abstract had me at "epochs of maxima".

We had joy, we had fun, we had epochs of maxima (seasons?) in the sun.

We would need to see the entire paper to understand the details of the long-term periodicity and how it allows finer-scale predictions for a specific solar cycle e.g.  when the north and south hemispheres become "in-phase" in certain solar cycles.

I noticed this abstract for a paper by the same author from 2017 which contains a bold set of predictions, including an early SC25 prediction:

https://link.springer.com/article/10.1007/s11207-017-1197-x

Edited February 20, 2023 by Drax Spacex
understand the details