New prediction of Solar Cycle 25

Prediction of Solar Cycle 25

Leif Svalgaard1*

1W.W. Hansen Experimental Physics Laboratory, Stanford University

Cypress Hall, C3, 466 Via Ortega, Stanford, CA 94305-4085

*Corresponding author: Leif Svalgaard (leif@leif.org)

ABSTRACT Prediction of solar cycle is an important goal of Solar Physics both because it serves as a touchstone for our understanding of the sun and also because of its societal value for a space faring civilization. The task is difficult and progress is slow. Schatten et al. (1978) suggested that the magnitude of the magnetic field in the polar regions of the sun near solar minimum could serve as a precursor for the evolution and amplitude of the following solar cycle. Since then, this idea has been the foundation of somewhat successful predictions of the size of the last four cycles, especially of the unexpectedly weak solar cycle 24 (“the weakest in 100 years”). 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.

Full paper here:

97 thoughts on “New prediction of Solar Cycle 25

      • I use my equation’s extrapolation which strictly is not a prediction; this means substituting year of the actual peak into the equation, see details of calculation in the link in my comment above. This could be a very long cycle and peak time is uncertain.
        Note: I still work in the old classic Wolf numbers, while Dr. S (as a co-author) uses new corrected and higher numbers, the ratio between the two is around 1.4.

        • This could be a very long cycle

          Puzzled because I thought the 11.1 year cycle was half the Hale cycle of 22.2 years. I thought the Hale cycle was the time it took for the Sun to orbit the centre of gravity of the solar system (or wobble, if you prefer). But I guess I’m wrong. The solar system barycenter follows a complex path. It’s hard to calculate a time since the sun doesn’t come to its original position but follows epicycloidal path.

          Given that, is there a relatively easy way to calculate the wobble periodicity of the sun?

          • Mark, is your comment addressed to me?
            If so I’m not sure of any relevance to what my comment is about. Average length of sunspot cycle has a centenary periodicity switching between 10.4 to 11 years,
            http://www.vukcevic.co.uk/SS.htm
            and Hale cycle would be about twice that.

          • Sorry, missed This could be a very long cycle
            Of recent cycles SC22 was shortest at 9.9 years and it was followed by SC23 at 12.3 years. Other long cycles were SC4 at 13.6, and SC5, 6 & 9 all in excess of 12 years.
            We are at the start of the SC25 but it is difficult to say when it’s going to hit its peak, since that period varies a lot: here is a list of the relevant times in years:
            SC 1 6.3
            SC 2 3.3
            SC 3 2.9
            SC 4 3.4
            SC 5 6.8
            SC 6 5.8
            SC 7 6.5
            SC 8 3.3
            SC 9 4.6
            SC 10 4.2
            SC 11 3.4
            SC 12 5
            SC 13 3.8
            SC 14 4.1
            SC 15 4.1
            SC 16 4.7
            SC 17 3.6
            SC 18 3.3
            SC 19 3.9
            SC 20 4.1
            SC 21 3.8
            SC 22 3.2
            SC 23 5.3
            SC 24 5.3

  1. What to think? Stanford has become a mixture of Science and Politics and it is difficult to know if any given theme is contaminated or not. I was in the field several times with the great Stanford Geology Professor Dr. Marco Einaudi, and he was a dedicated scientist for sure (and a great observer of geology in the field). Now Stanford has empowered the Woods Institute to focus on Climate Change Research. When you read their reports they are mixtures of actual research (effect of smoke on persons near California wildfires, for instance) and Global Warming tipping point nonsense. Stanford is great at one thing, getting alumni to maintain monetary support, so, follow the money. Solar cycle 25 will be a weak/low cycle, and two or three consecutive weak/low cycles tend to produce climate changes. We’ll see. I’m good for at least one more cycle.

    • Ron, I believe there is no reason to doubt the sincerity of Leif Svalgaard as a scientist. He often takes on sceptics that argue a strong connection to earth climate cooling with solar cycles of low sunspot numbers, but he does it with a thorough back up of data.

    • I’m confident that Leif is not part of the Woods Institute. Why do you assume that Woods is involved in astrophysics?

      He’s also older than I am, and that’s lots old. Stanford was a different place when Leif first joined them.

      • GAry and Ric, I am not down on Leif, it’s the Stanford tendency to mix politics and science, which appears to be the new norm these days.

  2. Leif,
    Thank you for your adherence to hard science when surrounded by opinion and guesswork so common in climate research these days.
    As the solar system moves to the next cycle, would it be appropriate to ask if there is, by now, any hard, acceptable evidence of a causal and/or predictive link between sunspot numbers (or related properties) and global climate (or parts thereof)?

    • Well, the solar cycle in the 1970’s was a low one, and the NYT had an article on January 5, 1978 claiming 30 years of global cooling with no end in sight.

        • I think Loydo’s use of “abruptly” is a sort of shorthand for “dramatically, unprecedentedly, dangerously, irrevocably, tipping-pointedly, icecap-meltingly, mass-extinctionally and (of course) anthropogenically”

          Apologies if I have missed any relevant adverbs.

      • “. . . temperatures have continued to abruptly rise.”

        Oxymoron there . . . needs revision.

        • Gordon,

          Loydo split an infinitive – terrible no-no. “to abruptly rise” should be written as “to rise abruptly” to be grammatically correct. I trust there are some English Majors out there who would support my adherence to orthodoxy.

          I am just a little bit sort-of serious here.

      • Solar irradiance is virtually unchanged in the chart you linked to – with a swing of less than 1/10th of 1 percent in half a century. But, to be fair, temps are way WAY up in your chart: roughly a WHOLE DEGREE in a half century.
        Thanks for terrifying me – I’m literally shaking right now.

        • Matthew,

          My understanding is that total solar irradiance varies very slightly but that the UV (high frequency) component can vary substantially. Can someone confirm or deny that?

      • temperatures have continued to abruptly rise

        Is this irony or are you just making it up like climate activists habitually do?

        • Such statements arise from one reading and listening to periodic reports from the MSM (and IPCC), which need to attract attention by one-upmanship over their previous “panic” reports . . . AND by the general lack of independent THINKING by those consuming such pablum.

  3. With the anemic start to SC25 so far, a prediction of 128 is looking a bit optimistic. We’re 10 months into SC25 and we just had a month of 3.3 and still spotless. Then again, your prediction for SC24 was pretty spot on.

  4. A distinct signature of when stable polar fields were established would be the appearance of the regular annual modulation of the observed field beginning after the irregular variations during the time of reversals at or about the time of sunspot maximum, as only a stable (or, at least, slowly varying) polar cap field would exhibit a regular annual variation in phase with the heliographic latitude of the observer …

    It is mildly surprising that this naturally observed annual modulation has nothing to do with the Earth revolving around the Sun. 😐

  5. So your prediction is 55-59 vs Dr S 118-138?

    How does your methodology differ, so as to give a prediction so much different and with greater precision?

      • Hi Rich
        Not exactly
        a) I still work in the old classic Wolf numbers, while Dr. S (as a co-author) uses new corrected and higher numbers, the ratio between the two is around 1.4, so Dr. S range in the old numbers would be about 84-98.
        b) I use my equation’s extrapolation which strictly is not a prediction; this means substituting year of the actual peak into the equation, see details of calculation in the link in my comment above. You are welcome to have a go providing you think you know the year that the SC25 is going to peak; I don’t since it could be a very long cycle.

        • Vuk. So what was the number system used for SC24, that we see illustrated on this site? Also I also see from your data that there is a strong hint of a harmonic stretching around 110 years, which helps a little with predictions.

  6. Leif,
    From your paper, “The many non-overlapping error bars illustrate the
    folly of even assigning error bars to the predictions or, at least, to believe in them”.
    This problem is widespread in science today. IMO it arises because researchers do not know the proper theory of how to estimate and express error ans uncertainty.
    To your knowledge, is there any convention or regulation (in USA at least) that requires procedures expressed in writing, for example such as the French-based Bureau of Weights and Measures, BIPM? Or, is it more common present custom to invent home brew methods to express uncertainty, such as a figure appearing in a regression on an Excel graph?

    • A measurement lab that opts to have their operations and data results accredited to the requirements of ISO 17025 (usually through a third-party accreditation agency) will be required to document and maintain an uncertainty analysis of its measurements. ISO 17025 requires the analysis adhere to the BIPM “Guide to the expression of uncertainty in measurement”. Another aspect of accreditation is that labs are required to participate in interlaboratory comparisons of their results as a way to confirm the reliability of the uncertainty analysis.

      In the past 10-15 years this has become much more common.

    • As I say in the paper:
      “People who use the predictions (such as NASA’s Flight Dynamics Group) require>/b> error bars. The errors are then used in Monte Carlo models of the satellite drag over the next sunspot cycle”

  7. Every month I look at the Silso http://sidc.be/silso/dayssnplot sunspot graphs (and the ‘SSN graphics’ link) for how sun cycle 25 is getting on. I am getting increasingly perplexed by their predictions. The latest month suggests further strongly suggests that their algorithm simply discards anything below the n highest points, where n seems to vary between 1 for their highest estimate and 3 for the lowest estimate. If that is in anyway correct, I would guess those numbers are percentages. They do give proper references for their smoothing/prediction algorithms, but all such algorithms are parameterized.

    Their estimates, as an exercise in statistics look more and more unrealistic. Then we have the Svalgaard & Hansen paper above, and their estimates seem to be sort of in line with the Silso predictions.

  8. With Solar Cycle 25 we’re refreshingly back in Popperland (deductive falsifiable science).
    Only 5-6 years to wait to see who’s right and who’s wrong.

      • There is no land other than Popperland. Every alternative is either quicksand, or mere illusory.

    • And, personally, I’m here still waiting to see visible sunspots that show that Solar Cycle 25 has actually started.

      Scroll down, looking on the right side of this webpage, to see the current yellow-orange “cue-ball color perfection” of the Sun’s disk under the heading link “Solar Images & Data Page”:-) Click on the heading to see an enlarged image.

        • Bob, your definition of “visible” is much, much more fluid than mine.

          Obviously, I can visually see a “X-ray” image, but my eyes cannot visually see in the X-ray portion of the EM spectrum.

          • OK, thanks. I grant you the spots for SC25 have been barely visible. Magnetograms see what our eyes can’t was my point.

            Today GONG is to visual observations like brain scans are to Phrenology.

            It would be nice to see more activity soon. It’ll happen.

  9. ON the layman’s side of the fence, is Cycle 25 a continuation of Cycle 24, with few to no sunspots, or is it expected to produce a change to increased spots.

    Whether yes or no, I want a nice, plain answer.

    And also, how much erratic weather in either hemisphere is the results of Cycle 24 and how much is not?

    • Solar cycles are separated by a magnetic pole flip in the sun. A sunspot peak of 124 would be much closer to cycle 24 than any of the other cycles in the satellite era.

    • That’s true, Robert, but things that one takes for granted are getting sort of kicked to one side. If there’s a possibility that instability in the solar cycles may occur, that’s what I was referring to.

      • Sara, you ask, “… If there’s a possibility that instability in the solar cycles may occur.”

        That’s a lot of conditionals: “if” and “possibility.”

        From all solar research there is no suggestion or hint solar cycles could become more unstable—whatever exactly you mean by that. Solar cycles vary in length and strength, but that variance is pretty well-constrained. Could we have another “Maunder Minimum” of several spotless cycles in a row? Sure, could happen; but data do not suggest that’s likely. Even if it happened, it’s happened before, so is not likely to be a concern.

        There is no evidence in the deep historical record (before 1600) that there’s been any dramatic changes in solar cycles that’s affected earth’s climate.

        Of all the things to worry about regarding climate, the sun and CO2 are two of the less significant issues.

        More concern there should be for oceanic cycles and Milankovitch Cycles. All else is the result of a random, chaotic system whose fundamental drivers are still not even close to being well-understood.

    • Each solar cycle starts at a low point in sunspots, which then increase to a peak midway through the cycle, then decline to another minimum at the end of the cycle. So,
      The transition from Cycle 24 (recently ended) to Cycle 25 (just started) is marked by low sunspot counts on either side of the transition point.

      The transition is determined by the change in the orientation of the sun’s magnetic field, which flips from “north” to “south” (and vice versa) to indicate the transition.

      From the preponderance of research, there seems to be little or no affect on weather or climate (chaotic or otherwise) due to sunspot cycles. Claims there is a relationship are not well-supported by most thorough-going research.

      And, by the way, there is no evidence weather is being any more chaotic in recent years or decades than in previous times. It’s only hyperbolic mainstream media and claims by some scientists (that are clearly contraindicated by the data) that drive this popular misconception. Hurricanes, tornadoes, wildfires, extremes in temperature are not getting worse/ more chaotic.

  10. 200 spotfree days so far, and the few of 25 have been pretty small and shortlived so far, from spaceweathers info
    always interesting to sit back n see what pans out.

  11. There are two types of energy that hits Earth from the Sun: photon based and particle based. The TSI is based on photons and is slightly lower during minimums, although the frequency distribution of the light varies. Energy coming from particles (solar wind and CME’s) almost never gets a mention, yet the amount in a flare or CME is huge.

    The active Sun we have had up to SC 24 blasted the Earth consistently with all kinds of ionized particles and had to have something to do with increased overall global temperatures. As the Sun has quieted down, so has the solar wind and there is a lot less energy coming our way via this pathway. The changes in our upper atmosphere also effects the jet stream allowing it to meander more during minimums. Statements that the TSI only varies a small percentage from active to quiet isn’t the whole story here on how solar cycles effect the Earth.

    Also the fact we have a quiet Sun doesn’t mean it still can’t let out a huge flare or CME. With the decreasing magnetic field of the Earth, we are becoming more susceptible to these and a Carrington event today would be an unmitigated disaster.

    • Dr Svalgaard will tell you that the cumulative proton mass hitting the Earth is about size of an average Thanksgiving turkey (the UK Xmas turkeys size is a bit more modest).
      On the other hand polar vortex is strongly ionised by CME’s, it is rotating at high velocity in presence of bifurcated magnetic field, hence basic laws of physics imply splitting of vortex following the “lines” of magnetic field intensity.
      See
      https://eoimages.gsfc.nasa.gov/images/imagerecords/36000/36972/npole_gmao_200901-02.mov
      and
      http://www.vukcevic.co.uk/NH.gif
      The vortex spreading out eventually will split it and vortex looses its strength, consequently it’s hold on jet stream is weakest allowing it to buckle and loop southward bringing cold spell .
      Locations of two magnetic peaks located in N. Canada and central Siberia lock jet stream in fixed position talking warm Pacific air to Alaska and cold Arctic air to N. America and Europe.
      https://max.nwstatic.co.uk/gfsimages/gfs.20190202/00/00/hgt300.png
      The effect is most noticeable in the winter months when the photon/light/TSI energy input in the Arctic area is at its lowest. Since solar flares and CME’s tend to be strongest in the second half of the sunspot cycle (magnetic sources of vigorous activity drift towards solar equator and our planet becomes more exposed to the direct line of fire) contributing to further cooling at times of solar mimima.

      • “Dr Svalgaard will tell you that the cumulative proton mass hitting the Earth is about size of an average Thanksgiving turkey (the UK Xmas turkeys size is a bit more modest).”

        That’s nice, although the relevant timeframe is missing.

        In addition, Einstein’s E=m*c^2 equation will tell you that about 1.9 kg mass-equivalence in PHOTONS hits Earth’s TOA every second! With an albedo of about 0.70, that means around 1.4 kg/sec (3 lbm/sec) of photons being “deposited” on Earth from the Sun, or the equivalent of about one average size broiler or fryer chicken (US standard) each second.

      • New unit of measure.. turkeys! Thanks for the polar vortex explanation.

        The “particles” hitting the Earth isn’t the mass that matters. Since they are basically ionized particles it is the electricity. We see low pressure systems intensify when hit by solar plasma, earthquakes happen and we certainly get a lot of lightning. Upper atmosphere changes occur as well as changes in our magnetic field structure. I think this is what needs more research, not CO2.

        Not to be an alarmist, but the decreasing Earth’s magnetic field strength and possible pole flip may have more impact than any increase in temperatures. It certainly bears investigation.

        • Indeed, it is not the mass ( the idea was to invite Dr. S to comment), it is the protons that ionise the highest levels of atmosphere, leading to polar vortex behaviour etc.
          On the matter of magnetic field, for the time being the relationship (not necessarily causal) is in revers proportion, i.e. weaker magnetic field dipole ‘higher’ the global temperature.
          http://www.vukcevic.co.uk/CT4-GMF.htm
          (Note the earth’s core to the solar spectral relationship, there is no convincing explanation available, the first time calculated few years ago (by vukcevic).

        • What is the mass-equivalence of a photon in the UV and/or visible bandwidth 300-750 nm?

          A 10 kg turkey divided by what?

          I’ve never believed photons have mass. Inertia maybe… but that’s a different topic.

          • UV Meter, for mass-equivalence of a photon:

            E=h*frequency=m*c^2, where h is Planck’s constant (h = 6.626 x 10^-34 J·s) and c is the speed of light in vacuum (3 x 10^8 m/s).

            Go forth and multiply (and divide).

            Careful with the units and related conversions.

          • It is really very simple:
            The solar wind hitting the Earth’s magnetosphere has a certain kinetic energy because it has mass moving at a certain [high] speed. A good-sized turkey moving hitting the Earth’s magnetosphere at the same speed has the same kinetic energy as the solar wind.

    • Interesting post. Can you give some comparative numbers, rough percentages would be OK, especially how they vary.

  12. If this method has successfully predicted the last 4 cycles then I’d say the progress on it was rapid, but the acceptance of it was rather slow lol.
    124 spot peak would be another moderately weak one.

  13. Cycle 25 will have very low sunspot numbers. I base this prediction on the fact I recently purchased a camera to attach to my telescope and can be used to photograph sunspots. And, on the laws laid down by the infamous Professor Murphy.

  14. I think the primary contribution of Dr.Svalgaard et.all. is to place a lot of emphasis on what we don’t know. Predictions can be made but they aren’t particularly strong. The history is short and the causal mechanisms are on a par with climate parameters in climate models. They don’t make uniform, fantastic predictions 10’s of years into the future because the research doesn’t support that.

    I just wish that climate scientists would admit that models driven by overall temperature averages are just plain wrong. None of the climate mechanisms we know about are driven by averages but occur on scales from sub-millimeter to millions of kilometers(solar effects).

  15. Hi Vuk
    Earlier in the year on this site, you posted a chart comparing SC24 with the just-starting SC 25,
    It showed how week 25’s start was then.
    With a recent run of 33 consecutive spotless days, the chart is even weaker.
    Could you post it?
    TKS

  16. Of the 25 groups or so shown daily on Spaceweather.com this past 2020, I have done three complete inventories of observable spots. I need an answer from someone. When I first studied solar observations I was told and read in the texts of the 1960’s that sun spots had to have both an umbra (red area) and a penumbra (dark area roughly centered on the umbra). With the development of satellites using UV light and magnetometers as sources for detection of areas of disturbances on the Solar disk, the ability to display the solar face using 4096 dpi is showing granular dots on the sun. My question is do 2 or three or even one dark granule constitute a sun spot currently? Looking at SDO 4096 HMI Colorized Magnetogram shows vast areas which are obviously magnetically disturbed and could well result in sun spots. However it appears that observer expectations sometimes result in calling these areas sunspot groups before they fit the definition of a sun spot I learned in the 1960’s

    As an example Spaceweather.com displays a daily sunspot count and what the AR number is if a spot/group is present. Spaceweather has been so helpful to my lying eyes as I now have a daily task where I look at Spaceweather.com and then SDO Solar Dynamics Observatory and compare their information.

    On September 23, 2020 a large plage of higher intensity white photons appeared on the east limb of the sun. It was labeled as a potential group. On September 24 it was labeled as AR2773. In the 4096 AIA 193A UV image it was a very active area with prominent magnetic field lines displaying complete coronal loops. Looking at it at highest magnification that I could use on Spaceweather there were two singular granule dark red spots in amongst the plage. The count given on Spaceweather was 13. On Sept 25 plage still active but only one single dark spot visible count given 0. Sept 16 AR2773 BACK!!!, count 11 when I looked at the image there were four single granules straining to appear darker. They in no way appeared to fit the definition of sunspots but they were in the middle of the UV image of the active area and they must be counted.

    On August 19, 2020 there were two active sunspot in AR 2772 as it approached the west limb of the sun. The larger of the 2 sunspots had a light bridge dividing the penumbra into two dark areas, it trailed the leading sun spot by a few degrees on the solar face. On the 20th of Sept these two area decreased significantly in size but still resulted in a total count of 15 sunspots for AR 2772. On the 21 Sept just to single granule spots remained in the midst of the magnetic storm which was the plage area of AR2772. On Sept 22 AR2772 went behind the limb of the sun. I would have started the 0 spot count on the 21st which would have resulted in a total of 34 days without spots before the supposed onset of AR2773.

    If the two weak spot days of Sept 24th and 26th are removed then we are currently at a count of 47 days with no sunspots. I would contend that today October 6 without a clear answer to my question above I will have to believe my lying eyes.

  17. I must give a lot of credit to spaceweather.com for their great work and assembly of data from so many sources. I sincerely hope that the continued throttling (censorship?) of publicly funded data is not visited on sites like WUWT and spaceweather because in a scientific debate, availability of un-corrupted data is essential to rational evaluation of theories and hypothesies.

    Dr. Svalgaard also seems to stick to data to validate his thoughts and while I do not always agree with his conculsions I respect his honesty and integrety

    Unfortunately in the Maurice Strong arena of CAGW scientific debate is laughed at, denigrated and attacked so that freedom of responsibility, individual choice and free speech will be entirely quashed and our betters will rule perfectly without regard to our souls. Who needs freedom?

  18. Solar activity during the solar minimum can also serve as a precursor for next cycle’s activity based on the same reasons.

    The SC24-25 solar minimum has been slightly deeper (1.8 vs 2.2 smoothed sunspots) and wider (~4 months longer) than SC23-24 solar minimum.
    https://i.imgur.com/GxIFhIQ.png

    We should therefore expect SC25 to be slightly less active than SC24, but not much. Perhaps 10-20 % less active.

    It doesn’t look good for all the people predicting a Grand Solar Minimum. Neither for those predicting a very active cycle. But it is good news for the satellites people. Satellites get to live longer and we get more bang for the buck.

    If my prediction from 2016 keeps being more or less right we are marching on towards a new Grand Solar Maximum. Did anyone order more warming? 🙂

    • …we are marching on towards a new Grand Solar Maximum. Did anyone order more warming?

      For what reason do you ascribe such impending long duration higher solar activity, not that I know one way or the other.

      The sun can warm w/o there being another Grand Solar Maximum, like it can cool w/o going into a GSMin, just not as much.

    • The SC24-25 solar minimum has been slightly deeper (1.8 vs 2.2 smoothed sunspots) and wider (~4 months longer) than SC23-24 solar minimum.
      The problem with using just solar minimum value is that the interval over which the smoothing is done is too short as there is fairly large random component to solar activity. We found that at least two [or better three] years [before the minimum] are needed to beat the noise down. And the smoothed value solar minimum is not a distinct physical phenomenon as it mixes activity from two cycles. A good example of failure of the min-method is the minimum before SC20 where SN = 14.3 at 1964.791, yet SC20 was rather low SNmax = 156.6 at 1968.874.

      • Ah, if only you would update your Active Region Count pages, Leif, so we could see for ourselves. Sad to see them without data since the start of 2018.

      • SC24-25 minimum belongs to the very selected group of slow solar minima, together with SC11-12, SC12-13, and SC23-24. SC5-6 minimum, “the Dalton Minimum” is a distant leader in this group. We haven’t seen anything similar since:
        https://i.imgur.com/ZtpMhAY.png

        The cycles that followed SC11-12, SC12-13, SC23-24, and SC5-6 were all low activity cycles. The cycles that preceded SC11-12, and SC23-24 were not low activity cycles.

        The rule so far is that slow solar minima, like SC24-25, can follow low or high activity solar cycles, but precede low activity solar cycles. It doesn’t look like the rule is going to be broken this cycle.

        Regarding the SC24-25 solar minimum, there is nothing special about it. We have three precedents.

      • My model is based on long solar cycles, and uses the integral of solar activity over the entire cycle (from minimum to minimum), so it does not give specific dates for maxima or minima, nor it gives maximum activity, as that depends on the distribution of the solar hemispheric maxima. If the North and South maxima take place close in time the maximal activity from the cycle is higher than if they are apart, as it happened in SC24; and if they are apart the cycle maximum will coincide with one of the hemispheric maximum and not the other.

        My forecast of future solar activity based on long solar cycles was produced in 2016. This was more than three years before the solar minimum. This figure was published in 2017:
        https://i.imgur.com/zt9Uc2P.png

        At that time I already had SC25 similar to SC24, and SC26 similar to SC23. I have refined the model a little since, but that hasn’t changed.

  19. Vuk

    There was a change when the magnetic field strengths reached the very minimum around 2014 during the double pole switch.
    That was IMHO the beginning of the new gb cycle. I predicted a few years ago that sc 25 will be more or less equal to sc24. Only from 26 the path is up again.

  20. Leif,
    With an uncertainty of +/-10 (unspecified, but presumably 1 sigma), the “8” in your estimate is not significant. You should have rounded up to 130. That is, with a variation in the ten’s position, the value in the unit’s position is meaningless. It is akin to multiplying two, 3-digit numbers numbers on your hand calculator and writing down all 15 digits shown on the screen. One of the advantages of a slide rule is that users were forced to round-off all calculations whether they understood the reasons for it or not.

    • With an uncertainty of +/-10 (unspecified, but presumably 1 sigma), the “8” in your estimate is not significant. You should have rounded up to 130. That is, with a variation in the ten’s position, the value in the unit’s position is meaningless.
      Nevertheless, it is customary in Physics to quote even the non-significant digits
      https://en.wikipedia.org/wiki/List_of_physical_constants
      e.g. Bohr magneton 9.2740100783(28)×10−24 J⋅T−1[18]

      • True in the commercial world too, as otherwise customers lose confidence in the expertise of the supplier.

        • Lot of stuff of any kind in the UK is sold at £xx.99. In the early years I found it very odd, eventually got use to but still think it is a bit of a con and the tradesperson insults shopper’s intelligence if they think they will buy something or another for £29.99 but will not for £30.00.

      • If you can’t measure it with the tools available then it is useless to quote more significant digits than you can measure. Who here has the ability to measure the speed of light to nine significant digits?

        • You can carry insignificant digits but not show them. That is why doing so is called “false precision”.

          It is not strictly necessary to give all numbers with a ± at the end. The correct use of rounding makes this unnecessary.

          Unfortunately it is easy for people to be fooled by extravagant claims for precision followed by a large uncertainty. False precision as to the value of the centre point of a range is also common. This last cheat is widely used in climate science to give the false impression of certainty.

      • Leif,
        However, in the case of an important physical constant, while uncertain digits are retained, they are accentuated by parentheses, and the constant and uncertainty are shown in scientific notation. Your “128” is not in the same class as the Bohr magneton. I suspect that the “(28)” pair is treated as guard digits and not given a lot of weight, but used to avoid introducing error in calculations.

        • However, in the case of an important physical constant, while uncertain digits are retained,they are accentuated by parentheses
          No. the digits in parenthesis are the 1-sigma error.
          My 128+-10 is the perfectly normal way of stating it.
          If I had said 128+-11 it would give a false precision of the error.
          The error bar is the hard part to get right.

        • https://physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html
          Use of concise notation
          If, for example, y = 1 234.567 89 U and u(y) = 0.000 11 U, where U is the unit of y, then Y = (1 234.567 89 ± 0.000 11) U. A more concise form of this expression, and one that is in common use, is Y = 1 234.567 89(11) U, where it understood that the number in parentheses is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.

      • “Nevertheless, it is customary in Physics to quote even the non-significant digits”

        None of the trailing values in these units are “insignificant”. These trailing digits are (1) all measured/calculated to an acceptable statistical certainty, and (2) most/all of these values have had their trailing digits (properly) used in subsequent calculations. I.e., many important physical observations are found from the tiniest of variations in some of these values.

        Clyde face plants when arm waving about the import of the probability distributions of the individual values of data sets under discussion, to the statistical durability of their resultant trends (almost nada, for the data sets he opines over), but he is dead on here…

  21. Javier told me a while ago that sun spots aren’t the most accurate source for looking at solar data during cycle minima. The F10.7cm radio flux would be better, he said, and he was right. Simply because you can have a long sequence of zero spot days, but the solar flux isn’t zero during that period.

    1. Here is a plot of the daily F10.7 averages during the minima of SC23/24 resp. SC24/25 transition periods:

    https://drive.google.com/file/d/1ls0t2D00ifmPGGsNJVYSDGjgwF-Xz_2B/view

    and here is the top 20 of an ascending sort of these daily averages since 2004:

    2019 10 21 63.4
    2019 10 23 63.9
    2019 10 24 64.3
    2019 10 20 64.4
    2017 11 9 64.6
    2019 10 22 64.9
    2007 9 30 65.1
    2008 11 28 65.2
    2008 12 22 65.5
    2018 11 4 65.5
    2019 10 19 65.5
    2008 11 1 65.6
    2018 3 8 65.6
    2018 11 13 65.6
    2019 10 17 65.6
    2019 10 18 65.6
    2018 11 28 65.7
    2008 10 29 65.8
    2009 2 10 65.8
    2018 11 1 65.8
    2019 10 14 65.8

    The first occurrence of 2020 is at position 286.

    2. Here is a plot of the monthly F10.7 averages during the minima of SC23/24 resp. SC24/25 transition periods:

    https://drive.google.com/file/d/1HxB0TsYFM8TtfX_amobgmVcGLb84n0Vx/view

    and here is the top 20 of an ascending sort of these monthly averages since 2004:

    2008 12 66.89
    2008 11 67.02
    2019 10 67.04
    2007 10 67.27
    2009 1 67.48
    2018 11 67.52
    2018 3 67.58
    2008 9 67.70
    2007 9 67.71
    2008 10 67.75
    2018 1 67.78
    2008 8 67.81
    2008 7 67.82
    2018 12 67.86
    2007 11 67.88
    2008 6 67.94
    2009 2 68.17
    2009 3 68.42
    2019 11 68.66
    2019 12 68.72

    The first occurrence of 2020 is at position 27.

    Source:

    https://www.spaceweather.gc.ca/solarflux/sx-5-en.php

    J.-P. D.

  22. Has anyone looked at older temp records to see where in a multicycle solar minimum we had climate cooling? Or is the temp data not available for SC 12-16?

    Also note the minor uptick predicted for SC25 is comparable to the minor variation within the 12-16 period cycle to cycle.

    • I’m sure all those computer models are ‘super‘, as British toffs once liked to say. Trouble is there aren’t any superhuman computer programmers.

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