Support the Arctic Sea Ice Forum and Blog

Author Topic: Solar cycle  (Read 22859 times)

blumenkraft

  • Guest
Re: Solar cycle
« Reply #100 on: July 13, 2020, 10:24:13 AM »
Hefaistos, your point is well received. The sun warms the earth. Heureka!

wehappyfew

  • Frazil ice
  • Posts: 120
    • View Profile
  • Liked: 22
  • Likes Given: 1
Re: Solar cycle
« Reply #101 on: July 13, 2020, 02:31:55 PM »
Hefaistos,

Your comments do not address the errors I pointed out.

The amount of solar energy impinging upon each square meter of the Earth is ~1360 W/m^2 divided by 4, since the Earth is a sphere.

Until you acknowledge this fact, you will continue to calculate the impact of a Maunder Minimum incorrectly.

anthropocene

  • Frazil ice
  • Posts: 108
    • View Profile
  • Liked: 19
  • Likes Given: 2
Re: Solar cycle
« Reply #102 on: July 13, 2020, 02:38:28 PM »
Confirming what wehappyfew has just posted:

Hefastios;  You are confusing irradiance with forcing.

THIS IS SHOWN IN FIGURE 2 OF THE LINK WHICH YOU PROVIDED. On the left-hand side is amplitude of solar irradiance (eye-balling the graph about 1.6 watts/m^2   and on the right hand side is the forcing: 0.25 watts/m^2). Hansen et al have done the conversion for you. It says " Left scale is the energy passing through an area perpendicular to Sun-Earth line. Averaged over Earth's surface the absorbed solar energy is ~240 W/m2, so the amplitude of solar variability is a forcing of ~0.25 W/m2."

 Either you are not understanding what is presented, not reading it all or wilfully cherry-picking quotes from scientific papers to make it look like they support what you say.  (Not for the first time either).

Also Figure 3 provides the GHG forcing (approx. 3 watts/m^2). So approx 12 times the amplitude  of a (unusually large?) solar cycle.

As you say yourself - OHC and surface temperatures are almost irrelevant side-effects ( ;-) ) of what happens at the TOA interface. So why do you complicate the discussion with these points? It could be taken as an attempt at a gish-gallop.

Either accept the points made by wehappyfew (and Hansen et al) or provide evidence to refute it and support your point.
 

 

Hefaistos

  • Guest
Re: Solar cycle
« Reply #103 on: July 14, 2020, 10:30:57 AM »
Hefaistos,

Your comments do not address the errors I pointed out.

The amount of solar energy impinging upon each square meter of the Earth is ~1360 W/m^2 divided by 4, since the Earth is a sphere.

Until you acknowledge this fact, you will continue to calculate the impact of a Maunder Minimum incorrectly.

Yes, of course, I was only mentioning the changes in solar irradiance. As you say, WHF, the incoming absorbed solar energy per unit surface area is S(1-a)/4
where a is albedo. On average, albedo is assumed to be around 0.3

The solar constant varies a bit over time, to get even numbers let's have it at S = 1360 W/m^2
The solar radiation at the TOA averaged over the whole surface of the earth = 340 W/m^2
The solar radiation absorbed by the earth’s climate system around 240 W/m^2 (depending on albedo).
The approximate radiation from the earth’s climate system at TOA also equals 240W/m^2 if we have energy balance (steady state). (which we don't, as the EEI is around 1 W/m^2 .

The solar 'constant' (S) varies a bit over time with the 11 year cycle, as seen in the CMIP6 forcing chart, its amplitude is about 1 W/m^2 during strong solar cycles, whereas only half of that during weak cycles.

Secondly, if we take the above figure for the Maunder minimum, it means a change in S with around -0.8 W/m^2 in S as a long term trend change.
At surface, with constant albedo it then adds about -0.14 W/m^2 in as a long term trend change in forcing.
I attach a chart with satellite measurements during 1978-1999. The absolute irradiation levels are much higher in those readings, but for some reason (why?) they have been aligned at the lower level of around 1361. (Also Hansen use the higher values)
« Last Edit: July 14, 2020, 10:39:30 AM by Hefaistos »

kassy

  • Moderator
  • Young ice
  • Posts: 2995
    • View Profile
  • Liked: 1262
  • Likes Given: 1165
Re: Solar cycle
« Reply #104 on: July 14, 2020, 03:20:23 PM »
At surface, with constant albedo

But actually we do not have a constant albedo. There is a year over year decline of ice cover in the mountains, landscape changes in Siberia, declining arctic sea ice and those changes alone will override it.

Also if you think the solar cycle helps us now that means we are in deeper trouble then we thought because of time scales.
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #105 on: July 14, 2020, 09:10:03 PM »
At surface, with constant albedo

But actually we do not have a constant albedo. There is a year over year decline of ice cover in the mountains, landscape changes in Siberia, declining arctic sea ice and those changes alone will override it.

The decline of which you speak amounts to ~0.2% of the total surface of the Earth.  Granted the change in albedo over that portion is rather large.  How much difference does changing cloud cover constitute?  What about the decrease in forest cover from ~40% to 30% since the dawn of industrialization?  Urban areas have roughly doubled to ~3% of the surface, which their contributing albedo changes. 

Incidentally, research has shown that the albedo has been remarkably constant over time:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014RG000449

Hefaistos

  • Guest
Re: Solar cycle
« Reply #106 on: July 16, 2020, 10:30:11 PM »
This is a recent paper estimating TSI, albedo, and OLR

"Measurement of the Earth Radiation Budget at the Top of the Atmosphere—A Review"
by Steven Dewitte and Nicolas Clerbaux,
 Remote Sens. 2017, 9(11), 1143;

"TSI measurements with good stability have been available since 1984. They reveal a variation of the TSI in phase with the 11-year sunspot cycle, with an amplitude of the order of 1 W/m2
. The currently-ending solar cycle 24 has a low amplitude compared to the preceding ones.
The TIM TSI instruments have a different viewing geometry as compared to the classical TSI instruments, which results in a lower absolute value of the measured TSI. Reconciling the classical DIARAD/SOVIM and the new TIM/TCTE instrument, the TSI level at solar minimum is estimated to be 1362.0 +/− 0.9 W/m2
.
The ERB measurements have sufficient stability to track the temporal variability of the EEI driving climate change, but they can not measure its absolute value with sufficient accuracy. Combining the ERB measurements with independent estimates of the EEI from OHC, we obtain the most likely values of the OLR of 238.0 W/m2
and of the RSF of 101.6 W/m2—corresponding to an albedo of 29.8%
—for the period 2000–2005."

https://doi.org/10.3390/rs9111143

https://www.mdpi.com/2072-4292/9/11/1143/htm

morganism

  • Frazil ice
  • Posts: 283
    • View Profile
  • Liked: 59
  • Likes Given: 1
Re: Solar cycle
« Reply #107 on: August 19, 2020, 02:19:56 AM »
NASA Researchers Track Slowly Splitting 'Dent' in Earth’s Magnetic Field

https://www.nasa.gov/feature/nasa-researchers-track-slowly-splitting-dent-in-earth-s-magnetic-field

" recent observations and forecasts show that the region is expanding westward and continuing to weaken in intensity. It is also splitting – recent data shows the anomaly’s valley, or region of minimum field strength, has split into two lobes, creating additional challenges for satellite missions.

“The observed SAA can be also interpreted as a consequence of weakening dominance of the dipole field in the region,” said Weijia Kuang, a geophysicist and mathematician in Goddard’s Geodesy and Geophysics Laboratory. “More specifically, a localized field with reversed polarity grows strongly in the SAA region, thus making the field intensity very weak, weaker than that of the surrounding regions.”

liefde

  • New ice
  • Posts: 55
  • ice melt will trump donald
    • View Profile
  • Liked: 8
  • Likes Given: 6
Re: Solar cycle
« Reply #108 on: August 29, 2020, 03:20:35 PM »
As the Earth Energy Imbalance at TOA is less than 1 W/sq.m. this effect is quite substantial.
Mike knows best:

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #109 on: August 29, 2020, 04:04:10 PM »
New research suggests Solar Cycle 25 could be strongest in 50 years
https://www.spaceweatherlive.com/community/topic/1775-new-research-suggests-solar-cycle-25-could-be-strongest-in-50-years/
Quote
Obviously, the thing that stands out the most is that they predict a massive cycle, similar to the solar cycles 19, 21 and 22, which were some of the strongest of the modern era of solar observations. The actual SSN they have predicted is 233, twice the size of the previous SC24 and about 50% stronger than the cycle before that one, SC23 (which peaked in around 2001).
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #110 on: August 31, 2020, 01:35:49 PM »
Did you read the comments and the links to NOAA and SILSO?

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #111 on: September 01, 2020, 12:53:11 AM »
Walrus, we are at the tea reading stage of forecasting solar cycles. Anything could happen.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #112 on: September 01, 2020, 03:06:56 AM »
Yes, and predictions range from low to high, pretty much the entire gamut.

kassy

  • Moderator
  • Young ice
  • Posts: 2995
    • View Profile
  • Liked: 1262
  • Likes Given: 1165
Re: Solar cycle
« Reply #113 on: September 01, 2020, 01:14:38 PM »
I suggest waiting for data from that cycle 25. 
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #114 on: September 01, 2020, 02:44:47 PM »
That would be best.

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #115 on: September 02, 2020, 12:43:59 PM »
But we won't get that for about a decade.
In the meantime, I like to read tea leaves (I'm impatient). Always remembering how shaky their reliability is.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

Alexander555

  • Nilas ice
  • Posts: 1323
    • View Profile
  • Liked: 151
  • Likes Given: 44
Re: Solar cycle
« Reply #116 on: September 05, 2020, 10:48:54 PM »

gerontocrat

  • Multi-year ice
  • Posts: 10423
    • View Profile
  • Liked: 3936
  • Likes Given: 31
Re: Solar cycle
« Reply #117 on: September 05, 2020, 11:21:21 PM »
One has to give Valentina Zharkova credit - she does not give up & still manages to get stuff printed.

Her work on the solar cycle and her predictions for a new Maunder Minimum is not accepted as credible by most scientists that study the solar cycle as their profession.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

morganism

  • Frazil ice
  • Posts: 283
    • View Profile
  • Liked: 59
  • Likes Given: 1
Re: Solar cycle
« Reply #118 on: September 07, 2020, 07:42:07 PM »
https://www.nature.com/articles/s41598-020-67860-3
On the correlation between solar activity and large earthquakes worldwide





We found clear correlation between proton density and the occurrence of large earthquakes (M > 5.6), with a time shift of one day. The significance of such correlation is very high, with probability to be wrong lower than 10–5. The correlation increases with the magnitude threshold of the seismic catalogue. A tentative model explaining such a correlation is also proposed, in terms of the reverse piezoelectric effect induced by the applied electric field related to the proton density.

we demonstrate that it can likely be due to the effect of solar wind, modulating the proton density and hence the electrical potential between the ionosphere and the Earth. Although a quantitative analysis of a particular, specific model for our observations is beyond the scope of this paper, we believe that a possible, likely physical mechanism explaining our statistical observations, is the stress/strain pulse caused by reverse piezoelectric effects. Such pulses would be generated by large electrical discharges channeled in the large faults, due to their high conductivity because of fractured and water saturated fault gauge. The widespread observations of several macroscopic electro-magnetic effects before, or however associated to large earthquakes, support our qualitative model to explain the observed, highly statistically significant, proton density-earthquakes correlation. It is important to note that our hypothesis only implies that the proton density would act as a further, small trigger to cause the fracture on already critically charged faults, thus producing the observed large scale earthquake correlation. Such a small perturbation would add to the main factor producing worldwide seismicity, which is tectonic stress.

morganism

  • Frazil ice
  • Posts: 283
    • View Profile
  • Liked: 59
  • Likes Given: 1
Re: Solar cycle
« Reply #119 on: September 07, 2020, 07:57:23 PM »
https://en.m.wikipedia.org/wiki/Flux_tube

When do solar erupting hot magnetic flux ropes form?
A. Nindos, S. Patsourakos, A. Vourlidas, X. Cheng, J. Zhang
We investigate the formation times of eruptive magnetic flux ropes relative to the onset of solar eruptions, which is important for constraining models of coronal mass ejection (CME) initiation. We inspected uninterrupted sequences of 131 Å images that spanned more than eight hours and were obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) to identify the formation times of hot flux ropes that erupted in CMEs from locations close to the limb. The appearance of the flux ropes as well as their evolution toward eruptions were determined using morphological criteria. Two-thirds (20/30) of the flux ropes were formed well before the onset of the eruption (from 51 minutes to more than eight hours), and their formation was associated with the occurrence of a confined flare. We also found four events with preexisting hot flux ropes whose formations occurred a matter of minutes (from three to 39) prior to the eruptions without any association with distinct confined flare activity. Six flux ropes were formed once the eruptions were underway. However, in three of them, prominence material could be seen in 131 Å images, which may indicate the presence of preexisting flux ropes that were not hot. The formation patterns of the last three groups of hot flux ropes did not show significant differences. For the whole population of events, the mean and median values of the time difference between the onset of the eruptive flare and the appearance of the hot flux rope were 151 and 98 minutes, respectively. Our results provide, on average, indirect support for CME models that involve preexisting flux ropes; on the other hand, for a third of the events, models in which the ejected flux rope is formed during the eruption appear more appropriate.
Comments:   A&A, in press
Subjects:   Solar and Stellar Astrophysics (astro-ph.SR)
Cite as:   arXiv:2008.04380 [astro-ph.SR]
    (or arXiv:2008.04380v1 [astro-ph.SR] for this version)

Hefaistos

  • Guest
Re: Solar cycle
« Reply #120 on: September 16, 2020, 07:47:53 AM »
A nice, interactive page where you can follow the progression of SC25, from NOAA. Including the official forecast for the strength and duration of SC25.

https://www.swpc.noaa.gov/products/solar-cycle-progression

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #121 on: September 16, 2020, 12:12:43 PM »
Hope Solar Orbiter and Parker Solar Probe get good observations of this solar cycle, and that Aditya-L1 gets a shot at it.
« Last Edit: September 16, 2020, 12:30:36 PM by Tom_Mazanec »
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

kassy

  • Moderator
  • Young ice
  • Posts: 2995
    • View Profile
  • Liked: 1262
  • Likes Given: 1165
Re: Solar cycle
« Reply #122 on: September 18, 2020, 05:19:34 PM »
Sea ice Triggered the Little Ice Age, Finds a New Study
https://phys.org/news/2020-09-sea-ice-triggered-age.html


The map shows Greenland and adjacent ocean currents. Colored circles show where some of the sediment cores used in the study were obtained from the seafloor. The small historical map from the beginning of the 20th century shows the distribution of Storis, or sea ice from the Arctic Ocean, which flows down the east coast of Greenland. The graphs show the reconstructed time series of changes in the occurrence of sea ice and polar waters in the past. The colors of the curves correspond to the locations on the map. The blue shading represents the period of increased sea ice in the 1300s.

A new study finds a trigger for the Little Ice Age that cooled Europe from the 1300s through mid-1800s, and supports surprising model results suggesting that under the right conditions sudden climate changes can occur spontaneously, without external forcing.

...

Martin W. Miles et al, Evidence for extreme export of Arctic sea ice leading the abrupt onset of the Little Ice Age, Science Advances (2020)
https://advances.sciencemag.org/content/6/38/eaba4320

Click on the link for the full text.

Also see post #71 up above for more hints that solar activity is not related to the events.
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

Alexander555

  • Nilas ice
  • Posts: 1323
    • View Profile
  • Liked: 151
  • Likes Given: 44
Re: Solar cycle
« Reply #123 on: September 21, 2020, 09:27:54 AM »
Lets assume that Valentina is right, that we enter a longer periode of lower solar activity. What would the impact be on rainfall ?

Hefaistos

  • Guest
Re: Solar cycle
« Reply #124 on: September 21, 2020, 01:41:06 PM »
Lets assume that Valentina is right, that we enter a longer periode of lower solar activity. What would the impact be on rainfall ?

Whether Valentina is right or not in her somewhat speculative forecasts I don't know.

What I know, is that there seems to be a positive relationship between solar TSI and cloudiness. Thus, less TSI in a solar minimum (like now) means less clouds and presumably less rain. That's the global averages.
« Last Edit: September 21, 2020, 01:57:48 PM by Hefaistos »

Alexander555

  • Nilas ice
  • Posts: 1323
    • View Profile
  • Liked: 151
  • Likes Given: 44
Re: Solar cycle
« Reply #125 on: September 21, 2020, 09:46:26 PM »
Yes it is speculative. But that 11 year cycle is pretty constant. And Valentina is talking about that 350 to 400 year cycle, that comes to an end somewhere now. And why would that not be constant ? Something is driving that 11 year cycle up and down, again and again and again.....Last cycle already had low numbers of sunspots. And now we have already many days with no sunspots at all. Something that don't happens that much. So the sun is not very active at all. I agree that there could be less rainfall if these low numbers would continue. Warm air can hold more moisture, so if it cools a little. But probably that will take many years, for the oceans to adjust.  And the same time we have been building mega cities and cutting down rainforests. That's probably the rain we will get less, compared with 20 or 30 years ago. I have a feeling we are going to hear more about it in the next years. Global warming vs solar cooling.

FishOutofWater

  • Grease ice
  • Posts: 875
    • View Profile
  • Liked: 486
  • Likes Given: 179
Re: Solar cycle
« Reply #126 on: September 25, 2020, 10:00:44 PM »
Interesting article about rapid sea ice transport leading to a cool period. That may not nix the volcanism theory if volcanic events could have brought on a stronger polar vortex by initiating polar cooling.

Back to the solar cycle. NASA has a new post about cycle 25 which is forecast to be just about the same as the last cycle.

https://www.nasa.gov/feature/goddard/2020/what-will-solar-cycle-25-look-like-sun-prediction-model

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #127 on: December 10, 2020, 01:08:11 PM »
Our Sun Has Entered a New Cycle, And It Could Be One of The Strongest Ever Recorded
https://www.sciencealert.com/the-new-sunspot-cycle-could-be-one-of-the-strongest-we-ve-ever-recorded
Quote
The Sun may be in for a very busy time. According to new predictions, the next maximum in its activity cycles could be the one of the strongest we've seen.
This is in direct contradiction to the official solar weather forecast from NASA and the NOAA, but if it bears out, it could confirm a theory about solar activity cycles that scientists have been working on for years.
A record sunspot number should mean record temperatures here on Earth.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

Niall Dollard

  • Grease ice
  • Posts: 803
    • View Profile
  • Liked: 316
  • Likes Given: 78
Re: Solar cycle
« Reply #128 on: December 10, 2020, 01:49:17 PM »
So much for Valentina Zharkova's "Grand Solar Minimum".

Her work has been heavily criticised in the past, containing basic errors.

https://www.newscientist.com/article/2209895-journal-criticised-for-study-claiming-sun-is-causing-global-warming/

vox_mundi

  • Young ice
  • Posts: 4956
    • View Profile
  • Liked: 2594
  • Likes Given: 382
Re: Solar cycle
« Reply #129 on: December 10, 2020, 02:23:13 PM »
New Sunspot Cycle Could Be One of the Strongest On Record, New Research predicts
https://phys.org/news/2020-12-sunspot-strongest.html

In direct contradiction to the official forecast, a team of scientists led by the National Center for Atmospheric Research (NCAR) is predicting that the Sunspot Cycle that started this fall could be one of the strongest since record-keeping began.

In a new article published in Solar Physics, the research team predicts that Sunspot Cycle 25 will peak with a maximum sunspot number somewhere between approximately 210 and 260, which would put the new cycle in the company of the top few ever observed.

The cycle that just ended, Sunspot Cycle 24, peaked with a sunspot number of 116, and the consensus forecast from a panel of experts convened by the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) is predicting that Sunspot Cycle 25 will be similarly weak. The panel predicts a peak sunspot number of 115.

If the new NCAR-led forecast is borne out, it would lend support to the research team's unorthodox theory—detailed in a series of papers published over the last decade—that the Sun has overlapping 22-year magnetic cycles that interact to produce the well-known, approximately 11-year sunspot cycle as a byproduct. The 22-year cycles repeat like clockwork and could be a key to finally making accurate predictions of the timing and nature of sunspot cycles, as well as many of the effects they produce, according to the study's authors.

Scott W. McIntosh et al, Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude, Solar Physics (2020)
https://link.springer.com/article/10.1007/s11207-020-01723-y




“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

Gray-Wolf

  • Grease ice
  • Posts: 895
    • View Profile
  • Liked: 124
  • Likes Given: 334
Re: Solar cycle
« Reply #130 on: December 11, 2020, 09:31:06 AM »
New Sunspot Cycle Could Be One of the Strongest On Record, New Research predicts
https://phys.org/news/2020-12-sunspot-strongest.html

In direct contradiction to the official forecast, a team of scientists led by the National Center for Atmospheric Research (NCAR) is predicting that the Sunspot Cycle that started this fall could be one of the strongest since record-keeping began.



What of the 'Climate Change Deniers' relying on a 'Maunder Like Minimum' to cool the Planet?

Over 2 decades of 'Fret Ye Not's' from them & now?

Will they warn of the 'Warming' an over active Sun must cause (if a min produces the cooling they warn us of?)

As for the rest of us we live in a modern World at risk of CME impacts on both satellites impacted by such & driven currents on the surface frazzling Electrical infrastructure....

We just don't seem to be able to catch a break eh?

Did we upset the Gods or something?
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
VIRESCIT VULNERE VIRTUS

KiwiGriff

  • Grease ice
  • Posts: 881
    • View Profile
  • Liked: 448
  • Likes Given: 159
Re: Solar cycle
« Reply #131 on: December 11, 2020, 09:51:27 AM »
Grey.
There are no gods.
We don't have a understanding of solar activity sufficient to confidently predict  future activity.
Anyone who does claim  such knowledge is probably pushing bullshite to minimize the future impacts of our unfortunate experiment in atmospherics physics.
Even a real maunder like minimum is only  going to delay the impact by a few decades at most.
http://www.realclimate.org/index.php/archives/2011/06/what-if-the-sun-went-into-a-new-grand-minimum/
Animals can be driven crazy by placing too many in too small a pen. Homo sapiens is the only animal that voluntarily does this to himself.
Notebooks of Lazarus Long.
Robert Heinlein.

Gray-Wolf

  • Grease ice
  • Posts: 895
    • View Profile
  • Liked: 124
  • Likes Given: 334
Re: Solar cycle
« Reply #132 on: December 11, 2020, 04:34:49 PM »
Hi KiwiGriff!

I thought the article was saying that the newly noted 22 yr magnetic cycle (offset from the 11 yr sunspot cycle?) offered the chance of better prediction of the Solar cycle to come with greater confidence?
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
VIRESCIT VULNERE VIRTUS

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #133 on: December 11, 2020, 05:14:23 PM »
Not too long ago, there were predictions of a new maunder-like minimum.  Now, this articles predicts "one of the strongest on record."  I am beginning to agree with Kiwi, except for the no God part.

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #134 on: December 11, 2020, 05:48:06 PM »
Gray-Wolf:
We only have a dozen full cycles of sunspot observation, only the last couple with modern satellite observations. And solar weather is very complicated. Trying to get patterns from that is tough. It is hard to know if there is something there or if it is just another Super Bowl Indicator or Curse of Tippecanoe.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

kassy

  • Moderator
  • Young ice
  • Posts: 2995
    • View Profile
  • Liked: 1262
  • Likes Given: 1165
Re: Solar cycle
« Reply #135 on: December 11, 2020, 06:51:37 PM »
The cool thing about this new research is that we should know by next cycle if they are on the right track or not because the prediction it makes is very different from the consensus one.

Basically they say it is an interference pattern so the length of the previous cycle determines the strength of the next. The internal mechanics are still shady but if it pans out we know where to focus next.

The whole maunder minimum link is an old and overly simple idea.

Quote
The Maunder Minimum, also known as the "prolonged sunspot minimum", is the name used for the period around 1645 to 1715

The Maunder Minimum occurred with a much longer period of lower-than-average European temperatures which is likely to have been primarily caused by volcanic activity.

and

The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period.[2] Although it was not a true ice age, the term was introduced into scientific literature by François E. Matthes in 1939.[3] It has been conventionally defined as a period extending from the 16th to the 19th centuries,[4][5][6] but some experts prefer an alternative timespan from about 1300[7] to about 1850.[8][9][10]

The NASA Earth Observatory notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, all separated by intervals of slight warming.

https://en.wikipedia.org/wiki/Maunder_Minimum
https://en.wikipedia.org/wiki/Little_Ice_Age
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

The Walrus

  • Grease ice
  • Posts: 926
    • View Profile
  • Liked: 77
  • Likes Given: 93
Re: Solar cycle
« Reply #136 on: December 11, 2020, 06:59:16 PM »
Gray-Wolf:
We only have a dozen full cycles of sunspot observation, only the last couple with modern satellite observations. And solar weather is very complicated. Trying to get patterns from that is tough. It is hard to know if there is something there or if it is just another Super Bowl Indicator or Curse of Tippecanoe.

We actually have over four centuries of sunspot observations, corresponding to more than 30 cycles.  Some have argued about the accuracy of said data, but it is still relevant.

https://astronomynow.com/2015/08/08/corrected-sunspot-history-suggests-climate-change-not-due-to-natural-solar-trends/

Tom_Mazanec

  • Young ice
  • Posts: 4282
  • Earth will survive AGW...but will Homo sapiens?
    • View Profile
    • Planet Mazanec
  • Liked: 630
  • Likes Given: 545
Re: Solar cycle
« Reply #137 on: December 11, 2020, 07:30:12 PM »
Odobenus rosmarus, the sunspot "cycle" is actually half a cycle, since each one is the inverse of the one before. Cycle 24 just recently ended, so that makes twelve "full" cycles.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

kassy

  • Moderator
  • Young ice
  • Posts: 2995
    • View Profile
  • Liked: 1262
  • Likes Given: 1165
Re: Solar cycle
« Reply #138 on: December 12, 2020, 06:39:35 PM »
We still count the 11 year cycles but if the NCAR prediction pans out we have to rework that since it is two interfering 22 year cycles. Anyway we won´t have to wait that long since it is the current cycle.

Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

Alexander555

  • Nilas ice
  • Posts: 1323
    • View Profile
  • Liked: 151
  • Likes Given: 44
Re: Solar cycle
« Reply #139 on: February 08, 2021, 11:52:56 AM »
Number of sunspots back at zero for already a couple days. http://www.sidc.be/silso/home

BeeKnees

  • Frazil ice
  • Posts: 292
    • View Profile
  • Liked: 55
  • Likes Given: 84
Re: Solar cycle
« Reply #140 on: February 08, 2021, 12:11:50 PM »
There is an active region just about to come into view.  So hopefully a few spots wont be far away.

Alexander555

  • Nilas ice
  • Posts: 1323
    • View Profile
  • Liked: 151
  • Likes Given: 44
Re: Solar cycle
« Reply #141 on: February 08, 2021, 05:19:02 PM »
Maybe we are lucky to be in a solar minimum since 2008. Otherwise we would have been closer to the 1,5 degree C as we are today.

WildFit

  • New ice
  • Posts: 29
    • View Profile
  • Liked: 15
  • Likes Given: 12
Re: Solar cycle
« Reply #142 on: February 08, 2021, 05:34:02 PM »
There is an active region just about to come into view.  So hopefully a few spots wont be far away.

I'd rather not want to see for example a solar miximum and the next el nino added to the current situation while i'm afraid that's more or less exactly what we're heading at and that could well be the moment when a few old questions of this forum will be answered in a hard awakening, at least as far as arctic sea-ice as well as aprupt sea-level-rise are concerned.

Why am I saying this here? Because of the "hopefully" word, I'm not hopeful at all while totally certain that high sun-activity is around the corner, means it's imminent.

interstitial

  • Grease ice
  • Posts: 895
    • View Profile
  • Liked: 269
  • Likes Given: 78
Re: Solar cycle
« Reply #143 on: February 09, 2021, 07:00:29 PM »
a sunspot is cooler so more sunspots equal less solar radiation equal lower earth temperature?

BeeKnees

  • Frazil ice
  • Posts: 292
    • View Profile
  • Liked: 55
  • Likes Given: 84
Re: Solar cycle
« Reply #144 on: February 09, 2021, 07:14:59 PM »
a sunspot is cooler so more sunspots equal less solar radiation equal lower earth temperature?
If sun spots weren't surrounded by higher energy areas that increase the amount of energy the earth recieves then I'd agree.

The (Total solar irradiation) TSI is higher at the peak of sunspot activity than at the minima

interstitial

  • Grease ice
  • Posts: 895
    • View Profile
  • Liked: 269
  • Likes Given: 78
Re: Solar cycle
« Reply #145 on: February 09, 2021, 08:24:32 PM »
a sunspot is cooler so more sunspots equal less solar radiation equal lower earth temperature?
If sun spots weren't surrounded by higher energy areas that increase the amount of energy the earth recieves then I'd agree.

The (Total solar irradiation) TSI is higher at the peak of sunspot activity than at the minima
Thats why I put the question mark at the end I figured I was missing something. Thanks for clarification.

A-Team

  • Young ice
  • Posts: 2770
    • View Profile
  • Liked: 717
  • Likes Given: 35
Re: Solar cycle
« Reply #146 on: February 15, 2021, 09:18:45 PM »
The bold NCAR prediction of an intense Solar Cycle 25 can easily be distinguished from the 10 other posted predictions, notably that of NOAA/SIDC’s panel of supposed experts, by near-term observation (fig.1) though not from early sunspot counts of 2021-22 (fig.2) nor toroidal oscillations (fig.3) — a decade of data will be needed to decisively determine the merits of the paired solar cycle proposal from SM McIntosh and colleagues.

Zharkova's lowball prediction, retracted by Nature's editor for cause, is not a contender but together with the NCAR high end scenario brackets the possibilities for total solar irradiance reaching the earth over the next 11 years. A high sunspot count could be significantly unfavorable to Arctic ice persistence.

The NCAR papers, while verbose and redundant, are easy to read: they do not contain any real physics (in the sense of solar magnetohydrodynamics) nor any actual math (outside of a dispensable Hilbert transform). The approach is entirely phenomenological — coordinated mapping of various data typets that extrapolate to a sunspot prediction number for Solar Cycle 25. That has significant implications for solar flare timing, astronaut safety, electric grid disruption, satellite damage, solar constant variation, Arctic Amplification and global warming.

The NCAR approach deprecates sunspot numbers as a mere end-product, proposing instead that associated 22-year Hale cycle observables are more fundamental. These include magnetic field polarity reversals, latitudinal distribution and migration extreme ultraviolet bright points, F10.7 radio flux, X-flares, extended cycle, g-nodes, magnetic multipole expansion, filament density, Fe XIV coronal green line emissions, Fe XII 195Å coronal scans, solar torsional oscillations, Wilcox solar polar field strength, collapse of the revised aa R27 index, Gleissberg modulation, and active region centroids that allow consistent wrapping of extended solar cycle terminators and pre-terminators.

These permit forecasting of the Solar Cycle 25 length, sunspot numbers, geomagnetic storms and earthbound increases in total solar irradiance. Success will provide strong physical guidance to interpretation of solar satellite imagery as well as to solar magnetohydrodynamic models that are not working yet. Only the Babcock-Leighton dynamo model is viable at this point.

There is important astrophysical carryover to a vast number of less easily observed sun-like stars via their Ca I spectrum. However little can be said about Solar Cycle 26 and beyond prior to the passage of SC 25 other than the NCAR approach would continue to apply.

Sunspots have a sorry history involving centuries of conspiracies, cranks, corporatist culprits (WUWT, Willie Soon), contrafactual nitrate enhancement in ice core layers, disputed increases in cloud nucleation, overstated global warming impacts relative to greenhouse gases and so on.

 If we assume that key NCAR predictions come to pass, the next eleven years of rising solar ‘constant' implies more radiative energy reaching the top of the earth’s atmosphere and so more heat retained, thus supplementing rather larger greenhouse gas effects. Extreme ultraviolet could affect stratospheric ozone and so indirectly methane lifetime. Enhanced galactic cosmic rays also affect Be-10 and C-14 production and so dating of ice core layers, tree rings and permafrost deposits

Still, the envisioned 0.1% increase has significance for climate change and loss of Arctic sea ice, exacerbating the ongoing increased open water trend during melt season which has already attained 56% as a Siberian-side semi Blue Ocean Event (subsequent posts). The issue is mainly decreased surface albedo, meaning more energy absorption into sea water and less electromagnetic reflection back out to space, as discussed earlier in the K Pistone papers.

McIntosh and colleagues have provided a game-changing unification of centuries of daily solar data collection, rectifying forty years of community neglect of Wilson's original extended solar cycle:

"Once you identify the terminators in the historical records, the pattern becomes obvious. A weak Sunspot Cycle 25, as the community is predicting, would be a complete departure from everything that the data has shown us up to this point… As Cycle 25 rises in 2020, it will likely be the last solar activity cycle that is not fully understood.”

Twitter and research gate pages:

https://twitter.com/swmcintosh
https://www.researchgate.net/profile/Scott_Mcintosh/publications 257 papers; 7417 citations
https://www.researchgate.net/profile/R_Leamon/research
https://earthsky.org/space/sunspot-cycle-25-among-strongest-on-record-says-ncar popular
https://twitter.com/hfsolar1 for current developments and animations

Below are open source links to 21 paper from the NCAR group, 16 oft-cited classics plus an explanatory glossary of sixty acronyms, technical terms and data sources commonly used. Links are also provided to satellite imagery display sites which can host spectacular displays. It’s convenient to list all the urls in chronological to and open all of them at once in web browser tabs using an open-all utility. Traditional astronomy does not use metric units (eg angstroms instead of nm) nor mainstream chemistry nomenclature (eg Ca XV roman numerals for Ca 14+ ions, not 15).

Acronyms and glossary:

-- TSI: total solar irradiance energy at top of earth's atmosphere, varies ~0.1% at 1361.5 W/m2
-- TOA: solar energy reaching top of earth’s atmosphere
-- SSN: sunspot number data set, Wolf number, ISN
-- SIDC: Solar Influences Data Center of Belgium Observatory official custodian of SSN sunspots
-- DRAO: Dominion Radio Astrophysical Observatory measures solar 10.7cm radio flux
-- SXI: Solar X-ray Imager satellites on  GOES providing continuous coverage of solar corona
-- SOHO: Solar and Heliospheric Observatory
-- SDO: Solar Dynamics Observatory
-- MDI: Michelson Doppler Imager instrument on SOHO
-- HMI: Helioseismic and Magnetic Imager on 45s cadence SDO dopplergrams from Mar 2010 on
-- EIT: Extreme ultraviolet Imaging Telescope on SOHO resolution ∼2.6 arcmin per pixel
-- AIA: Atmospheric Imaging Assembly telescope on SDO at 94, 131, 171, 193, 195 211, 335 Å
-- CSA: Gnevysheva's Catalog of Solar Activity
-- Yohkoh: solar X-ray measurements from 19 91 until lost in Dec 2001
-- Lomnicky Stit observatory in Slovakia: slit observatory of coronal green line Fe XIV 530.3 nm
-- Schwabe cycle (1844): the 11-year sunspot cycle
-- Hale cycle (1919): 22-year magnetic activity cycle of two 11 year sunspot cycles
-- Gleissberg cycle (1939): 88-year trend in Hale cycle envelope
-- ESC: Wilson’s extended solar cycle of two interdigitated cycles of a Hale cycle
-- Hale's law: leading sunspots have opposite polarities in N/S hemispheres cycle to cycle
-- Joy's law: paired sunspot axes tilt with latitude per by coriolis force on flux rope
-- Spörer's law: steady decrease of sunspot latitude in the solar cycle forms butterfly diagram
-- Solar flare classes: log scale smallest are A-class, followed by B, C, M with X largest
-- Halloween Storm: extreme geomagnetic X-flare event in 2003 (solar cycle 23)
-- Carrington Event: extreme geomagnetic storm in Sept 1859 (solar cycle 10) severe CME
—Wolf minimum: 1280-1350
— Spoerer minimum: 1420–1540) first of the Grand Minima
-- Maunder minimum: low sunspot activity 1645-1715 weakly tied to Little Ice Age
— Dalton minimum: 1800–1830) third of the Grand Minima
-- Synodic Rotation: a solar rotation day as adjusted to perspective of earth observers
-- CR: synodic Carrington Rotation taken as 27.3 days varies with latitude, depth and time
-- F10.7: flux at wavelength of 10.7 cm peak observed solar radio emission, measured by DRAO
-- aa index: antipodal magnetic activity; high-aa index corresponds to geomagnetic storms
-- acv(27): index that track 27 day recurrence in aa with respect to extended solar cycle
-- R27: autocorrelation of consecutive 27-day aa-index sets of high speed solar wind structure
-- AR: NOAA catalogue of active regions AR 12673 of Sept 6 2017 notable X9.3 flare
-- XSM: extended solar minimum, distinct from Extended Solar Cycle (ESC)
-- CME: solar coronal mass ejection of a solar flare detected by overall light emission
-- EUV: extreme ultraviolet emission in sun’s corona, proxy for solar radiative output
-- BP: bright point, small region of extreme ultraviolet emission
-- BMRs: bipolar magnetic regions consisting of sunspot pairs of opposite magnetic polarity
-- g-nodes: largest convective scale of photospheric magnetic granules 100-250 mega-meters
-- CBP coronal bright point
-- CGL: coronal green line of Fe XIV atoms 530nm, Fe X 635nm) red, Ca XV569 nm) yellow
-- CRF: incoming anti-correlated galactic cosmic ray flux
-- PCF: polar crown filament highest latitude magnetic neutral line
-- PCP: polar cap potential pattern in ionosphere from solar wind and Earth's geomagnetic field
-- PCH: polar coronal holes dark (cooler) low density regions of the sun's outermost atmosphere
-- SCZ solar convection zone that resides above liquid-like solar core
-- RTTP: rush to the pole, rapid migration of high latitude magnetic flux to poles reversing polarity
-- HCS: Heliospheric Current Sheet surface of solar wind marking magnetic field reversal tilt angle
-- Plage: a bright region in the chromosphere near sunspots
-- CF: coronal filaments cool dark arcs of plasma imaged with H-alpha line at 65.6 nm
-- CH: coronal holes small regions where magnetic field lines are open and solar wind escapes
— GCR: galactic cosmic rays reach earth when solar wind knocks down earth’s magnetic field
— IMF: interplanetary magnetic field distinct from solar and earth’s
-- Prominences: identical to filaments but bright against contrasting dark background of space
-- Faculae: small bright spots of photosphere below plage strongly influencing on solar constant
-- Tachocline: sharp increase in solar rotation between convective and radiation zones of interior
-- Magnetic Buoyancy: flux tube generated by solar dynamo rising to the photosphere as sunspot
-- Toroidal and Poloidal: solar magnetic fields winding about latitudes and rotational poles. resp.
-- MHD: magnetohydrodynamic dynamo involving interacting plasma flows and magnetic fields
-- Solar Dynamo: magnetic field convection and differential rotation vs ohmic and diffusive decay
-- Babcock-Leighton dynamo (1961): driven by oscillation of toroidal and poloidal fields
-- Torsional Oscillations: migrating zones of slower and faster rotation in the sun’s atmosphere

NCAR publications:

The Sun’s magnetic Hale cycle and 27 day recurrences in the ‘aa' geomagnetic index
SC Chapman SW McIntosh RL Leamon NW Watkins
https://arxiv.org/pdf/2101.02569.pdf Jan 2021

Deciphering Solar Magnetic Activity. II. The Solar Cycle Clock and the Onset of Solar Minimum Conditions
RJ Leamon SW McIntosh SC Chapman NW Watkins A Chatterjee AM Title
https://arxiv.org/pdf/2012.15186.pdf Jan 2021

Deciphering Solar Magnetic Activity: 140 Years Of The Extended Solar Cycle Mapping the Hale Cycle
SW McIntosh RJ Leamon R Egeland M Dikpati RC Altrock D Banerjee S Chatterjee E Cliver AK Srivastava M Velli
https://arxiv.org/pdf/2010.06048.pdf Nov 2020a

Investigating the Chromospheric Footpoints of the Solar Wind
P Bryans SW McIntosh DH Brook B De Pontieu
Astrophysical Journal
https://iopscience.iop.org/article/10.3847/2041-8213/abce69 Dec 2020

Prediction of the In Situ Coronal Mass Ejection Rate for Solar Cycle 25: Implications for Parker Solar Probe In Situ Observations
C Möstl AJ Weiss … SW McIntosh et al
Astrophysical Journal 903(2)
https://iopscience.iop.org/article/10.3847/1538-4357/abb9a1/pdf Nov 2020

Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude
SW McIntosh SC Chapman RJ Leamon R Egeland NW Watkins
Solar Physics 295, 163
https://link.springer.com/article/10.1007/s11207-020-01723-y 2020b

Timing Terminators: Forecasting Sunspot Cycle 25 Onset
RJ Leamon SW McIntosh SC Chapman NW Watkins
Solar Physics 295, 36
https://arxiv.org/pdf/1909.06603.pdf 2020

Solar Wind Helium Abundance Heralds Solar Cycle Onset
BL Alterman JC Kasper RJLeamon SW McIntosh
https://arxiv.org/pdf/2006.04669.pdf Jun 2020

SC Chapman SW McIntosh RJ Leamon NW Watkins
Quantifying the solar cycle modulation of extreme space weather
Geophysics Research Letters
https://doi.org/10.1029/2020GL087795 May 2020
 
What the sudden death of solar cycles can tell us about the nature of the solar interior
SW McIntosh RJ Leamon R Egeland M Dikpati Y Fan M Rempel
Solar Physics 294(7), 88.
https://doi.org/10.1007/s11207-019-1474-y. 2019

Signature of Extended Solar Cycles as Detected from Ca ii K Synoptic Maps of Kodaikanal and Mount Wilson Observatory
S Chatterjee D Banerjee SW McIntosh RJ Leamon et al
https://iopscience.iop.org/article/10.3847/2041-8213/ab0e0e Mar 2019

Termination of Solar Cycles and Correlated Tropospheric Variability
RJ Leamon SW McIntosh DR Marsh
https://arxiv.org/pdf/1812.02692.pdf 2018

The Extended Solar Cycle: Muddying the Waters of Solar/Stellar Dynamo Modeling or Providing Crucial Observational Constraints?
AK Srivastava SW McIntosh et al
https://arxiv.org/abs/1807.07601 Jul 2018

Deciphering solar magnetic activity: Spotting solar cycle 25
SW McIntosh RJ Leamon
https://www.frontiersin.org/articles/10.3389/fspas.2017.00004/full 2017

The detection of Rossby-like waves on the Sun
SW McIntosh WJ Cramer MM Pichardo RJ Leamon
Nature Astronomy 1, 0086
https://search.proquest.com/openview/a47af4b881fe7a0cbace68131300396f/1?pq-origsite=gscholar&cbl=4669719 2017

The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
SW McIntosh RJ Leamon LD Krista AM Title et al
Nature Communications 6, 6491
https://www.nature.com/articles/ncomms7491.pdf 2015

Deciphering Solar Magnetic Activity. I. On the Relationship between the Sunspot Cycle and the Evolution of Small Magnetic Features
SW McIntosh X Wang RJ Leamon et al
Astrophys. J. 792, 12.
https://arxiv.org/pdf/1403.3071.pdf 2014a

Identifying Potential Markers of the Sun’s Giant Convective Scale
SW McIntosh X Wang RJ Leamon PH Scherrer
Astrophys. J. Lett. 784, L32
https://arxiv.org/pdf/1403.0692.pdf 2014b

Hemispheric Asymmetries of Solar Photospheric Magnetism: Radiative, Particulate, and Heliospheric Impacts
SW McIntosh RJ Leamon JB Gurman JP Olive et al
The Astrophysical Journal 765, 146
https://iopscience.iop.org/article/10.1088/0004-637X/765/2/146/meta 2013

Solar Cycle Variations in the Elemental Abundance of Helium and Fractionation of Iron in the Fast Solar Wind
SW McIntosh KK Kiefer RJ Leamon JC Kaspe ML Stevens
Astrophys. J. Lett. 740(1), L23.
https://arxiv.org/pdf/1109.1408.pdf 2011

Nine Years Of EUV Bright Points
SW McIntosh JB Gurman
Solar Phys. 228, 285.
https://www.researchgate.net/publication/226563954_Nine_years_of_EUV_bright_points 2005
 
Auxillary publications:

Living Reviews in Solar Physics
Various Authors, regular revisions
https://www.researchgate.net/journal/Living-Reviews-in-Solar-Physics-1614-4961

DH Hathaway
Living Rev. Solar Phys., 12, 4
https://www.researchgate.net/publication/234373682_The_Solar_Cycle 2015

Forecasting long-term solar activity with time series models: Some cautionary findings
G Reikard
https://sci-hub.se/https://doi.org/10.1016/j.jastp.2020.105465  Dec 2020

Persistence of the Gleissberg 88‐year solar cycle over the last ∼12,000 years: Evidence from cosmogenic isotopes
AN Peristykh  PE Damon
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JA009390  2003

The aa indices: A 100-Year Series Characterizing the Magnetic Activity
PN Mayaud
http://isgi.unistra.fr/Documents/References/Mayaud_JGR_1972.pdf

Recurrent geomagnetic activity evidence for long-lived stability in solar wind structure
HH Sargent
J. Geophys. Res. 90, A2, 1425-1428
https://sci-hub.se/10.1029/ja090ia02p01425 1985

A revised 27 day recurrence index, arXiv:2101.02155
HH Sargent (forty-year update)
https://arxiv.org/pdf/2101.02155.pdf 2021

A Systematic Study of Hale and Anti-Hale Sunspot Physical Parameters
Jing Li
https://iopscience.iop.org/article/10.3847/1538-4357/aae31a Nov 2018

The Centennial Gleissberg Cycle and its association with extended minima
J Feynman A Ruzmaikin
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JA019478

The Topology Of The Sun’s Magnetic Field And The 22-Year Cycle
HW Babcock
http://adsabs.harvard.edu/pdf/1961ApJ...133..572B

On the variation of solar coronal rotation using SDO/AIA observations
J Sharma, B Kumar AK Malik HO Vats
https://academic.oup.com/mnras/article/492/4/5391/5731421?login=true

Computing the Discrete-Time Analytic Signal via FFT
SL Marple IEEE
https://sci-hub.se/10.1109/78.782222 1999

Asymmetry in Solar Torsional Oscillation and the Sunspot Cycle
B Lekshmi D Nandy HM Antia
https://arxiv.org/pdf/1807.03588.pdf 2018

On the origin of solar torsional oscillations and extended solar cycle
VV Pipin AG Kosovichev
https://arxiv.org/pdf/1908.04525.pdf 2019

Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions
P Bhowmik D Nandy
https://www.nature.com/articles/s41467-018-07690-0
 
What causes the inter-solar-cycle variation of total solar irradiance?
Nb Xiang and Df Kong
https://iopscience.iop.org/article/10.1088/0004-6256/150/6/171/meta 2015

Evolution of the Sun's Spectral Irradiance Since the Maunder Minimum
J Lean
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2000GL000043 2000

An Active Sun Throughout the Maunder Minimum
JBeer S Tobias NWeiss
https://link.springer.com/article/10.1023/A:1005026001784

Hydromagnetic dynamo models
EN Parker
Astrophys. J. 122, 293 (1955)
http://adsabs.harvard.edu/full/1955ApJ...122..293P

Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale
VV Zharkova, SJ Shepherd SI Zharkov E Popova
Scientific Reports 4336 (2020)
https://arxiv.org/abs/2002.06550
https://www.nature.com/articles/s41598-020-61020-3 retraction of Zharkova paper by editors

Data sources, imagery and explainers:

http://www.ngdc.noaa.gov/stp/space-weather/solar-data/solar-features/solar-flares/x-rays/goes/xrs/
https://www.nasa.gov/mission_pages/sunearth/news/X-class-flares.html
https://www.ngdc.noaa.gov/stp/solar/corona.html
https://en.wikipedia.org/wiki/Solar_cycle_25 ten predictions largest is 225 from NCAR
https://en.wikipedia.org/wiki/Solar_cycle
https://en.wikipedia.org/wiki/Solar_and_Heliospheric_Observatory
https://en.wikipedia.org/wiki/Magnetogram
https://scied.ucar.edu/
http://wso.stanford.edu/HCS.html
https://iopscience.iop.org/article/10.3847/1538-4357/aaa4f4/pdf
http://spaceweather.gc.ca/solarflux/sx-4-en.php
http://www.ngdc.noaa.gov/stp/solar/corona.html
http://solarscience.msfc.nasa.gov/greenwch.shtml
http://cosmicrays.oulu.fi/readme.html
https://arxiv.org/pdf/1710.06545.pdf
https://helioviewer.ias.u-psud.fr/ IASA Helioviewer
http://wso.stanford.edu/Tilts.html WSO tilt angle of the Heliospheric Current Sheet
http://www.sidc.be/silso/home SILSO daily total sunspot number from 1818
http://www.sidc.be/silso/cyclesmm Solar cycle maxima and minima
https://www.spaceweather.gc.ca/solarflux/sx-en.php Solar radio flux at 10.7 cm (F10.7 index) from 1947
http://isgi.unistra.fr/ aa index dataset from 1868
http://cosmicrays.oulu.fi/ GCR flux from 196
https://solarscience.msfc.nasa.gov/greenwch.shtml Greenwich Observatory-USAF/NOAA Sunspot areas 1874-2016
« Last Edit: February 16, 2021, 10:33:52 PM by A-Team »

oren

  • First-year ice
  • Posts: 6672
    • View Profile
  • Liked: 2450
  • Likes Given: 2165
Re: Solar cycle
« Reply #147 on: February 17, 2021, 07:18:33 AM »
Hullo A-Team, and thanks for this highly detailed overview of the subject.

A-Team

  • Young ice
  • Posts: 2770
    • View Profile
  • Liked: 717
  • Likes Given: 35
Re: Solar cycle
« Reply #148 on: February 19, 2021, 03:31:06 PM »
Quote
thx for detailed view of Solar Cycle 25
Subsequent posts need to go farther 'into the weeds' of geophysical time series, solar physics and solar satellite imagery before getting back to impacts of putative signficantly enhanced total solar irradiance (TSI) on Arctic sea ice over the next decade.

It's all predicated on the assumption, right or wrong, that the McIntosh NCAR group is correct (after 21 papers) in predicting an intense Solar Cycle 25. The aim is to combine the next cycle of predicted high solar 'constant' with ongoing greenhouse gas forcing and documented Arctic Amplification to estimate Arctic Ocean effects of more insolation energy going into low albedo open seawater during melt season and less reflected back out to space (even taking clouds into effect, see posts on Pistone 2019, 2014).

Enhanced TSI is accompanied by even more enhancement of extreme ultraviolet and so possibly more dissociation of stratospheric ozone (given already high CFC and NOx) thus possibly prolonging methane residency.

Effect estimates need to be done carefully because every aspect has been targeted by decades of climate denial up to and including trolling Solar Cycle 25 for a supposed Maunder-like minimum (bringing global cooling).

Solar cycles have numerous parallels to Arctic sea ice freeze/melt cycles in terms of preoccupation with trend statistics curve-fitting, compilation of long term historical records, time series of satellite imagery at unfamiliar wavelengths, and lack of adequate state variables (sunspot numbers don’t recapitulate photosphere dynamics; volume and extent don't capture ice pack strength).

Major solar satellites like Hinode (JAXA's Solar-B) are in near-polar satellite orbits just like those of the cryosphere but with instruments pointed at the sun rather than looking down at the pole. The view of the sun is full-disk, rather like Ascat’s of the Arctic Circle, with the difference being the quasi-geostationary equatorial view of the sun, reminiscent of many global weather products that are very distorted on the Arctic.

There's a fantastic guide to Hinode's instruments and accomplishments here:
https://directory.eoportal.org/web/eoportal/satellite-missions/s/solar-b

SUVI, one of several complementary instruments, images full-disk sun in the extreme ultraviolet wavelength range. It replaces the GOES Solar X-ray Imager (SXI) providing improved spectral coverage and spatial resolution. It observes complex active regions of the sun, solar flares, and solar filaments eruptions associated with coronal mass ejections.

https://www.goes-r.gov/spacesegment/suvi.html

Other solar satellites have left earth orbit, either sitting at agrangian points or even directly approaching the sun. There's been a push to to get satellites out of the ecliptic to better image solar poles and back side. This requires gravitational boomeranging about the moon or Mars (and years of delay). However the solar rotational axis has a 7.25º tilt with respect to the ecliptic plane so the poles are somewhat visible from the ecliptic during some portion of its 25-day rotation.

Solar satellites do not go back far enough in time in terms of 22-year Hale cycles. Thus the preponderance of relevent data is historical, patiently compiled by successive generations of observers at large and small astronomical observatories over the centuries.

The solar counterparts to clouds and water vapor obscuring the Arctic Ocean surface are solar wind, flares, eclipses, dark side of rotation, corona, transition zone, and chromosphere which lie above the sunspot's granulation-covered photosphere, the deepest layer of the Sun that can observed directly.  The sun’s surface is opaque to visible wavelengths because of overwhelming hydrogen anion. The radiative and convection zones above the fusion core can only be observed indirectly via helioseismicity analogous to the Polarstern's seismic study of seawater temperature below the ice bottom.

An over-reliance on models curses both solar and cryosphere climate research, never getting to the point of making forward predictions even a cycle or season out. NCAR's McIntosh writes:

Quote
"Over 1,000 refereed articles with 30,000 citations contain the phrase ‘solar dynamo’ in the title or abstract since 1970. The skeptical scientist may worry about the true size of the dynamo problem’s null space when so many researchers, wielding a vast array of models, can replicate these grand metrics but lack success when used in any forward-looking way without constant ingestion of data or adjustment of the array of 'free' parameters lurking in the background

Solar satellites are a long ways from the very large sun (1.39 million km diameter, 109 times that of Earth) but onboard telescopes can nonetheless get decent resolution at certain emission wavelengths. Hinode's optical telescope ends up with four million 175 km pixels, not nearly as good at AMSR2’s 6.25 km but with greater clarity and much faster cadence (45 seconds between scenes vs twice daily). Astronomers tend to use angular resolution, here corresponding to 0.25 arcsec. The doppler- and vector magnetograms have even faster cadence and sharper resolution but for partial disks.

Since the sun rotates fairly slowly with satellites all stuck on the earth side, as events continue to unfold on the far side during the 27 day synodic solar rotation, there’s no way to observe evolving features creating frustrating data gaps. Compounding the problem, atmospheric rotational speed varies with latitude in the solar atmosphere with torsional latitudinal bands oscillating on top of that. The sunspots do drift but systematically, vaguely like buoys in the TransPolar Drift. There’s solar cycle and hemispheric asymmetries analogous to yearly melt cycles and CAA side vs Siberian.

Hinode uses SvalStat at Svalbard for downloads just like Arctic satellites. The optical data is 12-bit, with lossy jpeg or lossless DPCM compression depending. Data transmission capacity can be a huge issue for remote solar satellites in terms of accuracy, lag, line of sight, solar wind interference and bandwidth capacity.

In terms of free software, ImageJ forked to AstroImageJ long ago. However ImageJ itself can be used with astro plugins. So far, that hasn’t been used in NCAR’s solar cycle papers beyond ‘unsharp mask’. They use various time series instead, along with various statistics and error analysis. It’s possible that graphical techniques developed for the Arctic can sharpen blurry dates of solar cycle events and so improve estimates of the rising solar constant in the decade ahead.
 
https://www.astro.louisville.edu/software/astroimagej/ free app, any platform
http://www.physics.umanitoba.ca/astro/?page_id=84 plugins
https://tinyurl.com/gx2z98k7 astrobytes overview

Overall, solar cycle research is trending for practical space weather matters: astronaut safety and grid disruption. Nuclear fusion, fashionable earlier, takes place at much greater depth in the core; the resulting neutrino emissions are monitored deep under the South Pole — their masses and lepton non-conservation are a slowly moving topic in contemporary particle physics. Solar ejecta can be very energetic yet velocities reached do not bring in special relativity. Magnetohydrodynamics is mostly Maxwell’s equations for ionized gases (plasma) plus Alven waves; Minkowski space and Lorentz transformations are implicit in those equations but again the treatment can be classical. General relativity, a topic in gravitational curvature, is measurable near the sun but too meagre to need consideration in solar atmosphere research.

Jupiter’s gravitational influence is sometimes invoked (unpersuasively) for Gleissberg cycles despite the sun comprising 99.86% of the total mass of the Solar System. The sun has axial precession, wobble and Coriolis forces but no overt counterpart to Milankovich cycles.   

The next post will cover early 2021 papers describing the new understanding of paired solar cycles and what can be expected from Solar Cycle 25 based on terminator-anchored re-wrapping of various multi-epochal datasets into what's called solar climatology.
« Last Edit: February 20, 2021, 03:11:44 AM by A-Team »

A-Team

  • Young ice
  • Posts: 2770
    • View Profile
  • Liked: 717
  • Likes Given: 35
Re: Solar cycle
« Reply #149 on: February 22, 2021, 11:34:47 PM »
Looking now at two 2021 papers of the NCAR program describing the crucial integration of even and odd Schwabe sunspot cycles into Hale cycles, veteran astronomer HH Sargent came out of retirement to update an oft-cited 40-year old paper ‘Recurrent geomagnetic activity evidence for long-lived stability in solar wind structure’ in coordination with the NCAR’s terminator-based remapping of Solar Cycles 11-25 by S Chapman et al in a paper called ‘The Sun’s magnetic Hale cycle and 27 day recurrences in the ‘aa' geomagnetic index’. (Links, terminology, background and motivation are provided in #146, #148 and below.)

Both papers analyze the long-term record of the “aa index” (antipodal average) based on the horizontal geomagnetic field strength measured with magnetometers at antipodal earth observatories. Despite variations, drift and sensitivity to the substorm current wedge associated with the earth’s own magnetic field, the aa index varies over short enough time scales to record changes in the sun’s high speed solar wind, thus serving as a proxy for it and even more indirectly for photosphere  observables behind it in the solar magnetic cycle. 

These include coronal streamers, dark coronal holes, bright active regions, solar flares, coronal mass ejection and dipole and toroidal solar magnetic field  components of the Babcock-Leighton dynamo, all tied together in recurrent geomagnetic storms on earth and issues in space weather that are of concern to astronauts, airplane passengers and crew, orbiting satellite electronics, and terrestrial electric grid.

The main reason for using the aa index is that its observational record dates back to Jan 1868. Only the sunspot record SSN is longer. The two together cover fourteen the 11 year cycles, deemed advantageous for analysis because solar behavior is only quasi-periodic (fairly noisy). The aa index and its many variants are based on the 3-hour K index measured two antipodal observatories, currently Hartland UK and Canberra AU and compiled into the aa index by PN Mayaud in 1972, extended to the present by others and is available online at 3-hour intervals with a 30 minute delay at ISGI (http://isgi.unistra.fr/).

The underlying K index was introduced by J Bartels in 1939. It assigns numbers to geomagnetic disturbances of the earth's magnetic field on aninteger scale 0–9; low values indicating calm, high values geomagnetic storms. Thus it is reminiscent of the Beaufort scale for wind or Richter for earthquakes. The K comes from the German word Kennziffer for "characteristic digit". The procedures needed to convert nano-tesla field strengths seen at different observatories at different latitudes in different decades into a consistent K index (and thus a consistent aa index) are described at https://en.wikipedia.org/wiki/K-index.

More than a dozen ISGI-endorsed variations on the K index are in use. Eight of them can be plotted online, limited to one year intervals (fig.1 below). These are potentially helpful in updating journal articles to early current Solar Cycle 25 (eg fig.1 updates 1868-2020 to Jan 1 to Feb 17 of 2021). These are often co-displayed with SILSO monthly mean sunspot number. The main idea is to synchronize cycles by their terminators, compare across solar cycles 11-24, and average epochs  into a solar ‘climatology’.

aa (since 1868):  two antipodal stations the longest record, measures geomagnetic activity with sensitivity to substorm current wedge
aaH (since 1868):  similar to aa but adjusted for nightside auroral electrojet of substorm current wedge
am (since 1959):  similar to aa but ring of 24 stations, am for amplitude
Kp (since 1932):  mid-latitude planetary geomagnetic activity index
Dst (since 1957):  storm-time disturbance arising from different physical processes-
Dcx (since 1957):  storm-time disturbance extended
Dxt (since1957):  storm-time disturbance extended and corrected                   
AE (since 1957):  auroral electrojet index
PC (since 1975):  polar cap magnetic index

* positive values of Dst: compression of the dayside magnetosphere early in a magnetic storm
* negative values of Dst: magnetic reconnection and formation of the storm-related ring current

http://wdc.kugi.kyoto-u.ac.jp/dstdir/  Dst
http://dcx.oulu.fi/  Dcx
http://dcx.oulu.fi/Dxt  corrected Dcx
http://www2.mps.mpg.de/projects/sun-climate/data.html  sunspot-group area data 
ftp.ngdc.noaa.gov  dates of solar cycle minima

In the first paper, Sargent uses a statistical method called autocorrelation to find periodic cycles in the aa time series over 152 years. There are a lot of data points, namely 443,840 = 24/3 x 365 x 152, that are linked to but not attached as supplemental. Autocorrelation looks at standard Pearson correlation between data points for a given choice of offset (lag) in the time series. It can be done online at a small scale at the links below to bring the analysis forward to Feb 2021. Adding 2 months to a 152 years times series would be of marginal interest except that SC 25 is just getting underway.

https://en.wikipedia.org/wiki/Autocorrelation
http://www.alcula.com/calculators/statistics/correlation-coefficient/
https://www.socscistatistics.com/tests/pearson/default2.aspx
https://byjus.com/linear-correlation-coefficient-calculator/

The sidereal 27-day is a natural choice for a solar autocorrelation lag. It defines Sargent’s R27 index, a plot of correlation magnitude vs calendar date picking up the 11-year Schwabe solar cycles 11-24 quite well. It is co-plotted together with sunspot numbers in fig.2 below. To avoid smoothing issues and artifacts, it works better to pool 3-hour values into a 3-day rolling average rather the 12-hour used in early papers. These ideas surfaced earlier as epoch stacking (Bartels rotation charts).

Rapid rises in R27 index are associated with an abrupt fall in sunspot numbers defining NCAR terminators. High correlation implies a stable solar wind structure emanating from the sun at this point in each solar cycle. Low correlation means that noise dominates the geomagnetic disturbances on earth (as measured by the aa averaging of the K values of horizontal field component).

Near-earth solar winds that disturb its geomagnetic field have three origins: high-speed streams >450 km/s associated with polar coronal holes at the sun, slow inter-stream solar wind and transient flows originating with equatorial solar streamer belt coronal mass ejections (CMEs). Low geomagnetic storm activity during the cycle 23 minimum of 2008 is without precedent over the last 80 years but has questionable implications for future cycles.

The revised R27 paper co-plots SSN and R27 in a helpful high resolution graphic (fig.3). On that can be seen that even cycles are double-peaked (Gnevyshev Gap); the underlying solar cycle magnetohydrodynamics is nicely explained by Georgieva 2011. Odd cycles are too but less noticeably. This asymmetry between odd and even cycles, not yet considered in the NCAR papers, provides another compelling line of support the need to organize two 11 year cycles into one 22 year complete cycle. There are a half-dozen or more known Hale cycle dependencies including magnetic polarity reversals, solar minima, galactic cosmic ray flux but not solar cycle maxima.

In its 5th figure, the Chapman paper co-plots averaged solar maxima and minima of the last 18 solar cycles along with terminators and pre-terminators for the last 12 solar cycles along with F10.7 index. The latter refers to solar radio flux at 10.7 cm (2800 MHz), an excellent overall indicator of solar activity that is not ‘Hale cycle’ dependent (no apparent odd/even bias). It is one of the longest running records of solar activity — six full cycles from 1946 on — and is easily observed from ground radio telescopes in all weather without record gaps or calibration issues. The emissions originate high in the chromosphere and low in the corona of the solar atmosphere from Fe XIV ions.

Since F10.7 also correlates well with SSN, EUV, solar flares, TSI and everything relatable to them, all those could also have been co-plotted. For example, extreme ultraviolet impacts to the ionosphere of the earth as well as stratosphere and ozone level could have been added. This would result in far too complicated a circular track display so the nutty literal display of [0,4π] radians in complex plane phases is better dropped in favor of co-registered, selectable vertical layers.

A tileable GIS gif stack scaled to Hale cycle widths would allow any subset of co-variables to be abutted in any order in a graphic, what is called in solar research a ‘superposed epoch analysis’ or, if averaged out, solar climatology. Given varying numbers of consecutive Schwabe cycles abutted to Hale cycles, this corresponds to an ImageJ hyperstack which comes with a manipulation menu: a simple horizontal flip of an extra copy of any layer generates a derived layer quantitating any Hale cycle dependence.
 
The Chapman papers regularize Hale cycle width (aka time) using an obscure data-driven method called Hilbert transform. This sidesteps various artifactual periodicities brought in early data smoothing and has the benefit of kicking out low frequency longer term trends as a byproduct, here something suggested to be the 88-year Gleissberg cycle. The authors don’t comment on 4 x 22 = 88 nor speculate on underlying solar physics. It’s not clear exactly where in the Gleissberg cycle the onset of Solar Cycle resides nor what the impacts on prediction would be.

From the mathematical perspective, there are perhaps better options within harmonic analysis of time series than a Hilbert transform.  Indeed, a 2020 paper from the same group skips fourier transforms altogether and just normalizes cycle lengths to inter-terminator widths which amounts to piecewise linear time compression/expansion (that could be refined matching internal points such as pre-terminators, maximums, minimums, even/odd and peak splitting from any of the co-variables. Some of these have fuzzy timing and would only introduce error.

So, getting back to the solar satellites and their myriad observational products, it may be possible sharpen terminator and internal point timing for the last last 30 years, maybe bringing in new and better ones, and so benefit cross-cycle  re-calibration for climatology alignment and aid near-term forecasting. However there are zero prospects for SC26, SC27 etc except in the vaguest terms as forward modeling has consistently failed.

Recent solar physics papers from other scientists use related tools such Hilbert-Huang transforms, singular spectrum analysis (SSA), empirical mode decomposition (EMD) and synchro-squeezed wavelet transforms (SWT) which may produce sharper time-frequency components, the tools optimized for extracting  intrinsic mode function decomposition applicable to non-stationary features of a quasi-periodic signal such as sunspot number. References below provide  explanations and practical applications to high latitude solar quasi-biennial oscillations (QBO), Rieger periodicity and the magnetic plage strength index (MPSI).

https://sci-hub.se/https://doi.org/10.1093/mnras/staa1061  Deng 2020
https://iopscience.iop.org/article/10.3847/1538-4357/aa7d52/pdf  Feng 2017
https://www.sciencedirect.com/science/article/pii/S1063520310001016  Daubechies 2011

Getting back to the aa index, it will always play a principal role being the longest record. However it partly conflates earth magnetic field variation with the fast solar wind that it’s supposed to be proxying. If it can be refined with a better starting series, say the modified aaH index studied in three 2020 papers by JJ Takalo (which tracks the nightside auroral electrojet of the substorm current wedge), that puts less of a load on later harmonic analysis.

Sargent notes transitions between disordered and 27 day recurrent structure in the aa index occur on a timescale of 2-3 solar rotations, that duration of this 27 day recurrent structure is almost twice as long during even cycles compared to odd ones, and ‘excellent agreement’ exists between R27 cross-overs with NCAR terminators. Those are not shown on the plot but done more conveniently in the Chapman revision of Sargent’s revision (fig.3) which includes two additional predicted terminator dates at the peripheries.

The 2021 paper by Chapman et al recomputes aa index autocorrelation for all reasonable choices of lag, not just the 27 days. This produces overtones at 54 days and indeed a faint 81 day. This says the R(27) autocorrelation is transitive as it spans three cycles, implying stability of the solar wind structure to timing of the solar cycle.

The actual NCAR prediction for Solar Cycle 25 is 233 sunspots, twice as many as SC24 and half again more than SC23, with 95% error bars of 153 and 305 spots. For our purposes, only the total solar irradiance of SC25 matters to earth climate and especially Arctic melt season ice but details matter in how NCAR gets to it and with what reliability.

The length of time between each terminator event inversely correlates with the strength of the upcoming cycle. For example, the terminator length prior to SC24 starting was about 12.8 years (happened in 2011) - leading to rather weak cycle. The SC25 terminator is expected to occur this year (9 years gap) - and that correlates with a strong cycle. The average seems to be around 10.5 years.

The McIntosh group’s proposal for SC25 is bold, yea-or-nay testable (but how soon?), with major implications for solar physics and possibly earth climate) if right. It’s not clear yet whether 1-2 years of SC25 are enough to discriminate their prediction from NOAA’s dozen-expert panel’s but a whole-cycle wait of ten years won’t be necessary.

However solar climatology averaging may have limited applicability to SC25 prediction. This is not sampling with replacement as in probability theory. It is all about SSN and terrestrial aa index being the only long-term records. This may over-weight them or bring in extraneous physics that is long gone bye. Both records are too far downstream from the underlying physics driving the Babcock–Leighton dynamo. 

For SC25, the question is how much memory the sun really has. Some would say none, it's Maxwell’s equations with a future entirely determined from the present (neglecting convection zone chaos, magnetic reconnection, flares, advection, CMEs etc). Yet there is an element of hysteresis here in that the present can’t actually be specified without including recent historical trajectory. However there may be rapidly diminishing returns after bringing in just the last 2-3 cycles. Here though the Wolf (1280-1350), Spörer (1450-1550), Maunder (1645-1715) and Dalton (1790-1820) grand minimums raise strong cautionary notes.

The aa indices: A 100-Year Series Characterizing the Magnetic Activity
PN Mayaud
http://isgi.unistra.fr/Documents/References/Mayaud_JGR_1972.pdf

A revised 27 day recurrence index
HH Sargent (forty-year update)
https://arxiv.org/pdf/2101.02155.pdf 2021

Recurrent geomagnetic activity evidence for long-lived stability in solar wind structure
HH Sargent
J. Geophys. Res. 90, A2, 1425-1428
https://sci-hub.se/10.1029/ja090ia02p01425 1985

A Geomagnetic Activity Recurrence Index
HH Sargent (initial book chapter)
Solar-Terrestrial Influences on Weather and Climate
https://link.springer.com/chapter/10.1007/978-94-009-9428-7_10  1979
 
The Sun’s magnetic Hale cycle and 27 day recurrences in the ‘aa' geomagnetic index
SC Chapman SW McIntosh RL Leamon NW Watkins
https://arxiv.org/pdf/2101.02569.pdf Jan 2021
 
Using the aa index over the last 14 solar cycles to characterize extreme geomagnetic activity
SC Chapman RB Horne NW Watkins
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL086524  2020a

Quantifying the solar cycle modulation of extreme space weather
SC Chapman SW McIntosh RL Leamon NW Watkins
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087795  2020b

Deciphering Solar Magnetic Activity: 140 Years Of The Extended Solar Cycle Mapping the Hale Cycle
SW McIntosh RJ Leamon R Egeland M Dikpati RC Altrock D Banerjee S Chatterjee EW Cliver AK Srivastava M Velli
https://arxiv.org/pdf/2010.06048.pdf Nov 2020a

What the sudden death of solar cycles can tell us about the nature of the solar interior
SW McIntosh RJ Leamon R Egeland M Dikpati Y Fan M Rempel
Solar Physics 294(7), 88.
https://doi.org/10.1007/s11207-019-1474-y. 2019

DH Hathaway
Living Rev. Solar Phys
https://www.researchgate.net/publication/234373682_The_Solar_Cycle  2015

Comparison of Geomagnetic Indices During Even and Odd Solar Cycles SC17 – SC24:
Signatures of Gnevyshev Gap in Geomagnetic Activity
J Takalo
https://arxiv.org/pdf/2012.05061.pdf 2020 aaH refined index

Why the Sunspot Cycle Is Double Peaked
K Georgieva
https://www.hindawi.com/journals/isrn/2011/437838/  2011

The 22‐year cycle of geomagnetic and solar wind activity
EW Cliver  V Boriakoff  KH Bounar (even/odd cycles are different —> full cycle is 22 years)
https://sci-hub.se/https://doi.org/10.1029/96JA02037  1996

Terrestrial-Magnetic Activity and its Relations to Solar Phenomena
J Bartels  (original Bartel ‘rotation’ chart)
doi:10.1029/TE037i001p00001  1932

Some additions and fixes to post #148 which no longer allows editing:

— Solar neutrinos, despite being produced exclusively in the sun’s core by nuclear fusion, still exhibit quasi-biennial oscillation (QBO) in production rates seemingly tied to sunspot-type magnetic variations much higher in the solar atmosphere. This suggests either that the core has temperature or structural variation or that outer magnetic fields interact with a neutrino magnetic moment. Neutrinos are very inconvenient to observe and only in 2019 could those resulting from CNO fusion be seen. On route to the earth, they can change lepton number indicating low but non-zero mass after many decades of textbook denial. However it has not been possible to do more than set an upper bound on the common neutrino, less than 1eV. About 100 billion solar neutrinos pass through a thumbnail-sized area every second with no effect. See http://www.stil.bas.bg/ISWI/PDFsN/Vecchio_2010.pdf

— The solar tachocline above the core in the differentially rotating convective zone of the sun’s atmosphere is said to have magnetic Rossby waves m=1 type, another similarity of sorts to familiar concepts from earth’s upper atmosphere.

— Metallicity is another poorly chosen term unique to astronomy. It refers to the abundance of elements heavier than helium in stars such as nitrogen or neon. Hardly any of these elements form metals (solids with shared conducting electrons) as that term is understood in chemistry or metallurgy.

— Polar faculae are small bright objects with complex structure on both polar caps of the Sun that can be observe in panchromatic visible light, Ca K lines or in Fe chromospheric lines. The word means ‘little torch’. The chromospheric counterpart of a facular region is called a plage. Faculae represent concentrations of magnetic field lines between solar convective granules. They contribute significantly to variations in solar output. Facular points have unipolar kilo-gauss magnetic fields of the same polarity as the global poloidal magnetic field. Polar faculae counts anti-correlate with sunspot area  with a six year phase lag.

http://solarwww.mtk.nao.ac.jp/en/db faculae.html  long-term tabulation of polar faculae

— There’s an active Space Weather blog site similar to Arctic Sea Ice forum
https://www.spaceweatherlive.com/community/topic/1775-new-research-suggests-solar-cycle-25-could-be-strongest-in-50-years/