Sunspots Today: A Cheshire Cat – New Essay from Livingston and Penn

This arrived in my email tonight from Bill Livingston. It is hot off the press, date June 11th. I believe WUWT readers will be some of the first to see this. – Anthony

Guest Essay by:

W. Livingston, National Solar Observatory, 950 N. Cherry Ave, Tucson AZ 85718;

M. Penn, National Solar Observatory, Tucson AZ

Physical conditions in the infrared at 1.5 microns, including maximum magnetic field strength and temperature, have been observed spectroscopically in 1391 sunspots 1990 to 2009 (1). We emphasize the quantitative difference between our IR sunspot measurements and the visible light results from most solar magnetographs employed world-wide. The latter are compromised by scattered light and measure flux, not field strength. A lower limit of ~1800 Gauss is required to form spot umbra. The umbral maximum field strength has declined over the above interval, perhaps because spots have on average diminished in size. The present condition of solar activity minimum has more spotless days than since the 1910s (2). The Cheshire Cat behavior is related to magnetic surface fields often appearing without accompanying dark spots.

Sunspots recently are behaving like a Cheshire Cat: the smile is there (magnetic fields) but the body is missing (no dark markings). We are unsure about past cycles but at present sunspots, with their usual umbrae and penumbrae, are failing to materialize. For hundreds of years the Sun has shown an approximately periodic 11-year alteration in its activity where the number of sunspots increases and then decreases. Sunspots are dark regions on the solar disk with magnetic field strengths greater than 1500-1800 Gauss. The last sunspot maximum occurred in 2001. Magnetically active sunspots at that time (Figure 1A) produced powerful flares, caused large geomagnetic disturbances, and disrupted some space-based technology.

Livingston-Penn-Chesire_Fig1A

Figure 1a. An image of a sunspot from near the maximum of the last solar cycle, cycle 23, taken at the McMath-Pierce telescope on 24 October 2003. The sunspots clearly show a dark central umbra surrounded by a brighter, filamentary penumbra. The magnetic fields seen here range from 1797 to 3422 Gauss.

At present, presumably leaving a deep solar minimum, nothing more than tiny spots, or “pores”, have been seen for some time (again

Figure 1B).

Livingston-Penn-Chesire_Fig1B

Figure 1b. An image of a pore – a tiny sunspot with no penumbral structure – taken from the MDI instrument on the SOHO spacecraft, 11 January 2009; this is an example of what we observe today at solar minimum. The larger pore had a magnetic field of 1969 Gauss. Presently, the solar surface is mostly devoid of spots. Both images have the same spatial scale, and are roughly 360 Mm horizontally.

In the current solar minimum the number of spotless days has not been equaled since 1914 (2), see Figure 2. Some look at this figure and feel reassured; this has

happened before. Others sense abnormality.

Livingston-Penn-Chesire_Fig2

Figure 2. Number of spotless days at cycle minima in the past.

Why is a lack of sunspot activity interesting? During a period from 1645 to 1715 the Sun entered an extended period of low activity known as the Maunder Minimum. For a time equivalent to several sunspot cycles the Sun displayed few sunspots. Models of the Sun’s irradiance suggest that the solar energy input to the Earth decreased during that epoch, and that this lull in solar activity may explain the low temperatures recorded in Europe during the Little Ice Age (3).

In 1990, working with S. Solanki, we began exploratory measurements at the McMath- Pierce telescope of the infrared magnetic field strength, temperature, and brightness in dark sunspot umbrae. These observations use the most sensitive probe of sunspot magnetic fields: Zeeman splitting of the infrared spectral line of Fe I at 1565 nm. This splitting yields total field strength not flux (see below). Because the splitting is always complete in sunspot umbrae the measurement is independent of atmospheric blurring, or seeing (providing the line is visible). Temperature was deduced from the depth of nearby molecular OH lines. Higher temperature meant brighter continuum intensity and weaker OH. Starting in 2000 this work became systematic, where each spot was measured only once at the darkest position in its umbra. The resulting data set of 1391 observations represents the longest time-sequence of total field strengths in sunspots. Figure 3 is a plot of these observations.

Livingston-Penn-Chesire_Fig3

Figure 3. Maximum magnetic field vs. continuum brightness for all data 1990-2009.

We believe most of the scatter is real; the errors are likely to be in intensity and not field strength. Sky transparency and image quality, or seeing, are of course somewhat variable and this affects intensity. Data with obvious clouds were discarded. Two conclusions: 1) there is not a unique relation between sunspot brightness and magnetic field and 2) the lower limit to the magnetic field to produce a dark marking is around 1500-1800 Gauss. This lower limit is uncertain because of noise in intensity (brightness) signals.

It was also found that the magnetic field strengths in umbrae were on average decreasing with time independent of the sunspot cycle. Or it may be that spots are simply getting smaller (4). OH has practically disappeared today. A simple linear extrapolation of our magnetic data suggests that sunspots might largely vanish by 2015, assuming the 1800 Gauss lower limit, see Figure 4.

Livingston-Penn-Chesire_Fig4

Figure 4. The maximum sunspot total field strength is plotted versus time, during the period from 1992 to Feb 2009; a 12 point running mean is shown, and a linear fit to the data is made. Apart from a few measurements, the linear trend has been seen to continue throughout the present solar minimum.

The brightness and magnetic fields of large sunspots had earlier been discovered to change in-sync with the solar cycle as seen by ground-based telescopes (5). Automated solar magnetographs (e.g. Mt Wilson, Kitt Peak, SOHO) measure surface magnetic flux using spectral polarization signals from the Zeeman effect. Flux measurements are subject to scattered light; the fields they deduce in sunspot umbrae are much less, often by a factor of two, than the field strength given by the Fe 1564 nm splitting (6). The latter does not involve polarization sensing. Magnetograph instruments, however, are in wide use both in space and ground-based –with a time span going back over 50 years. They do record non-sunspot magnetic flux (which the simple non-polarized Fe 1564 nm splitting cannot do) and have detected the onset of the next solar cycle active regions. This deduction is based on the expected high solar latitude hemispheric magnetic polarity reversal, the “Hale cycle”. Yet all new cycle number 24 spots that we have observed have been tiny “pores” without penumbrae (e.g. Figure 1). Nearly all of these features are seen only on magnetograms and are difficult or impossible to see on white-light images. Thus the analogy to the Cheshire Cat [Roberts, 2009].

Physical explanations of this deep minimum are at present speculative. Modelers invoke flux transport, meridional flows, and other subsurface mechanisms. Whether this diminished vigor in sunspots is indicative of another Maunder Minimum, remains to be seen. We should mention, too, that the solar wind is reported to be in a lower energy state than found since space measurements began nearly 40 years ago (7). Will the Cheshire Cat Effect persist?

References:

1. Penn, M.J. and Livingston, W., Temporal Changes in Sunspot Umbral Magnetic

Fields and Temperatures, Astrophys. Jour., 649, L45-L48, (2006).

2. Janssens, J., Spotless days website, (2009)

http://users.telenet.be/j.janssens/Spotless/Spotless.html

3. Lean, J., A. Skumanich, and O. White, Estimating the Sun’s Radiative Output

During the Maunder Minimum, Geophys. Res. Lett., 19(15), 1591–1594 (1992).

4. Schad, T.A., and Penn, M.J. (2008), Solar Cycle Dependence of Umbral

Magneto-Induced Line Broadening, EOS Trans. AGU 89(23), Jt. Assem. Suppl. Abstract

SP41B-06 (2008).

5. Albregtsen, F. and Maltby, P., Solar Cycle Variation of Sunspot Intensity, Solar

Physics, 71, 269-283 (1981).

6. Private communication from J. Harvey, (2009).

7. Fisk, L.A., and Zhao, L., The Heliospheric Magnetic Field and the Solar Wind

During the Solar Cycle, in Universal Heliophysical Processes, Proceedings of the

International Astronomical Union, IAU Symposium, Volume 257, pp 109-120 (2009).

Acknowledgement:

Roberts, Harry, Sydney Observatory, private communication re. Cheshire Cat (2009).

A PDF version of this essay is available here: Livingston-Penn_sunspots4

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TerryBixler

We only watch and wonder what is happening next with our sun. Thank you Anthony and Bill Livingston for the hot off the press update.

Jeff L

Leif, What say you ??, esp. about figure 4 & the argument field strength will be too weak to support visible spots by 2015?

John F. Hultquist

If I understand this post we do not currently know what this activity of the Sun means, and, possibly we will know soon, and it won’t be pleasant.
Fantastically interesting.
Also, I like that Fig. 4’s linear fit (the black line) stops where it does for, surely, what goes down sharply could reverse just as quickly. I wonder who will be the first to extend the line and post it?

Anaconda

No one can predict because no one understands…the mysteries of our Sun.

John F. Hultquist

note
Thousands of demonstrators have rallied across Australia to demand greater government action to protect the environment from climate change.
http://news.bbc.co.uk/2/hi/asia-pacific/8098452.stm

No no no, this article doesn’t hold water, it fails the most elementary test. The authors failed to mention that their conclusions confirm that currently perceived global cooling is non-existent and/or an aberration, a deceptive and false blip in the constant upward thrust of burning planet syndrome.
Where is their confirmation that the Sun has minimal effect on the unprecedented searing temperatures?
Where is their confirmation that a quiet Sun can only have one effect, namely to accelerate the warming of the plant?
I think these gentlemen simply don’t understand the rules of the game.

Bill Jamison

It’s great to get an update of this information – thanks for the post!

Love how the establishment astronomers are so desperate to see sunspots they are making specks out to be beams.
Leif, given how the threshold of “what is a sunspot” seems to be dropping fast, and given your past revisionism of sunspot records based on individual astronomers practices, perhaps we need to adjust the past record to make a proxy record of past pore counts?

Anaconda (22:35:56) :
No one can predict because no one understands…the mysteries of our Sun.
Yes, you’re right… And the Sun is getting older and unpredictable each day. Solar cience is not settled… yet; at least not in the real world.

I ate a “s” at “Solar science is not settled… Sorry. 🙂

rbateman

Outstanding work Bill Livingston.
Most of the spots we have seen this year are truly pores.
A group called Ergebrisse has been calculating the “sunpores” in a more precise manner than SWPC/NOAA.
I will post up graphs of thier counts sometime in the next day or so.
Furthermore, the white-light facular counts are and have been on a footing of a full magnitude fainter than 1911-14.
There are no cycle transitions for white-light facular counts equal to or lower than 2006-09, for which counts are available. None.
http://www.robertb.darkhorizons.org/DeepSolarMin3.htm
1899-1902 was quieter for 1901, but was shouldered by high counts.
I believe that any Grand Minimum is an animal of it’s own character, no two being identical. I sense the abnomality of Grand Minimum, but in it’s own making different from any previous. Not the Maunder, Dalton, Wolf, Sporer or Oort.
The Eddy Minimum.

Leon Brozyna

Wonderful — the year 2015 isn’t that far away. And we shouldn’t have to wait that long to see if this idea is onto something; it should keep showing up (or not showing up) over the next 2-3 years to further solidify these ideas.
Should be interesting to see how SC 24 & 25 bear up and how many plage regions show up w/o associated spots (or with very minimal spots). Plage cycles or Cheshire Cat cycles; whatever, these must be the most interesting time in which to be studying the sun.

Gene Nemetz

“Yet all new cycle number 24 spots that we have observed have been tiny “pores””
These could be seen with telescopes of the Little Ice Age times…..especially on cloudy days. There is homogeneity in the sunspot record.
———————————
p.s. seriously, this was a good post!
WUWT—Best Science Blog 2009!

deadwood

John F. Hultquist (22:42:34) :
Thousands of demonstrators have rallied across Australia to demand greater government action . . .

Yup, the government will be able to control climate change. As much chance of that as of controlling the sun. Oops, forgot its the same thing.

Just Want Results...

FatBigot (22:49:54) :
No no no, this article doesn’t hold water… I think these gentlemen simply don’t understand the rules of the game.

Wait a second—you formed an opinion of a post about the sun before waiting to see what Leif thinks of it. That’s sort of breaking a rule too… for some.

rbateman

Gene Nemetz (23:10:54) :
These could be seen with telescopes of the Little Ice Age times…..especially on cloudy days. There is homogeneity in the sunspot record.

I don’t think so. When they fade out in front of your 70mm refractor that is better than the telescopes of the LIA (25mm- Galileo), they faded out for them also. I had the unsavory honor of attempting to project as spot with Lief that I had clearly seen 1.5 hrs earlier. And we tried twice. When they Cheshire, they are gone for traditional purposes. There is little solace to be found there.

In their last analysis on Hematite Stained Grains (HSG), Bond et al logged a peculiar percentage corresponding to the last period of 70 years, which makes the graphs on HSG to go down abruptly since 1935 AD.
I could explain the abrupt falling through the current decrease of insolation in the northern hemisphere; however, this could mean that not only the sunspots number has dropped down, but in general the solar irradiance during the last 74 years.
I would question the assumption on equaling the sunspots number with the intensity of solar irradiance. It is evident that there is something more over there… Something which have escaped to our observations and satellite sensors.
Perhaps the accuracy of the satellites nowadays is so high that it seems that the Sun is spitting the same load of energy than it was before the advent of satellites, when in reality it was brighter and more energetic in the past? The latter conjecture would make some solar students bristle their hairs. I know what I will be told in few minutes… “Hey! Nasif! It’s a conjecture! But I suppose the puppy already has disappeared with the pancake.

tobyglyn

Gene was joking.

Trevor

John F. Hultquist (22:42:34) :
Thousands of demonstrators have rallied across Australia to demand greater government action . . .
It was a fizzer. Dominated by a variety of lefty socialist groups. BBC is grasping at straws. What is making the news is the cold weather and the great start to the ski season.

James H

Hey, I just Leif on the National Geographic Channel today. He was talking about the sun and sunspots. The program was about diminishing solar activity and previous cold periods. It was a summary of many of the theories that we see, cosmic rays vs. solar wind, sunspots and cooling, etc.

John in NZ

If this continues, pretty soon we’ll have negative sunspots.
But seriously folks, Someone once told me the sun has periods of boom and bust. The boom has finished. Now we have bust. How long the bust goes on is a matter for debate but these small spots don’t promise a ramping up any time soon.
BTW here in NZ things are still fairly cool for this time of year.( Yeah, I know, it’s just weather.)

General weakness of polar magnetic fields may be another indicator of the changes taking place. This may be just a coincidence, but if strong divergence (just started) of polar fields before minima is any guide, then this minimum is not done yet.
http://www.geocities.com/vukcevicu/PFdiv.gif

Physical explanations of this deep minimum are at present speculative. Modelers invoke flux transport, meridional flows, and other subsurface mechanisms. Whether this diminished vigor in sunspots is indicative of another Maunder Minimum, remains to be seen.
Science remains baffled….just observers really. Those of us in the know are not surprised, its following the script to perfection.

Richard111

Any estimates for the number and size of spots that formed on the other side of the sun?

Here is another plot of Livingston’s data [he graciously keeps me up to date]: http://www.leif.org/research/Livingston%20and%20Penn%20-%20Umbral%20Data.pdf
The pink points show the contrast [1 meaning invisible] and the black points the magnetic field. None of these data have been smoothed [I hate smoothing]. The big dots show the yearly averages in an obvious manner.
National Gepgraphic also has this short article: http://news.nationalgeographic.com/news/2009/06/090612-sun-lowest-peak-activity.html

Tenuc

Seems we still have much to learn about the mechanisms driving the sun and it’s interactions with our climate.
It is interesting that the reduction in the suns ability to produce strong magnetic fields mirrors the reduction in the Earth’s magnetic field.
I wonder if this reduction in electro-magnetic energy is reflected in a reduction in lightening storms across the globe???

Jeff L (22:21:01) :
Leif, What say you ??, esp. about figure 4 & the argument field strength will be too weak to support visible spots by 2015?
if the field strength falls to some 1500-1800 Gauss, the contrast is so close to one that the spot is invisible. If the field strength falls well below 1500 Gauss, the sunspot will appear bright rather than dark.

rbateman

The key to the pore counting monkeybusiness is in the 10E-6 hemispherical area figure:
—- — — — W# Hm – —- — – – – – – – –
2009 05 31 69 15 30 1 -999 A0.0 0 0 0 0 0 0 0
2009 06 01 73 23 80 0 -999 A1.3 0 0 0 0 0 0 0
2009 06 02 72 19 60 0 -999 A0.0 0 0 0 0 0 0 0
2009 06 03 73 17 10 0 -999 A0.0 0 0 0 0 0 0 0
2009 06 04 71 17 20 0 -999 A0.0 0 0 0 0 0 0 0
2009 06 05 70 13 10 0 -999 A0.0 0 0 0 0 0 0 0
Bad Monkey!

Leif Svalgaard (00:23:49) :
“if the field strength falls to some 1500-1800 Gauss, the contrast is so close to one that the spot is invisible. If the field strength falls well below 1500 Gauss, the sunspot will appear bright rather than dark.”
bright spots? Has that actually happened before? Have bright sunspots actually been observed?

Mike McMillan

Had the privilege of visiting the Kitt Peak solar telescope back in ’69. They were still grinding the Mayall 4meter mirror at the time. The solar scope projected an image of the sun that must have been 4 or 5 feet across on a table. Found a page about the Kitt Peak magnetograph and those splitting Zeeman lines.
http://eo.nso.edu/dasl/Lessons/dasl_data.html

Andrea

I’ve read Livingston&Penn’s work and I find it very fascinating but I think they are extrapolating datas over a too small time interval (1990-2006) with little significance…

rephelan (00:54:19) :
bright spots? Has that actually happened before? Have bright sunspots actually been observed?
In a sense, yes. They are called faculae. There are many examples of bright areas on the Sun with moderate magnetic fields, but no visible sunspots. Some even recently.
Very speculatively: it is possible that during the Maunder Minimum, there was actually significant solar activity [we know, f.ex. that the cosmic ray modulation was strong back then], but that magnetic field was just at or below the 1500 Gauss that makes the spots invisible. Perhaps TSI was even higher then without the black spots to drag down the values. This idea will be strongly opposed by those that for other [non-solar, e.g. anti-AGW] reasons cannot accept such heresy.

Excellent post. This is turning into what must surely be one of the most significant science stories of our age.
Just out of curiosity, have any of our close stellar neighbours (e.g., the Alpha Centauri system) also gone into “quiet sun” mode recently?
Re the “thousands” (or even hundreds!) of demonstrators rallying across Australia this weekend, I also note that Canberra has just had its coldest June day since 1966.
Were he taking part in one of those rallies, the Cheshire Cat might have said: “You can’t help that. We’re all mad here.”

Gerard

John F. Hultquist (22:42:34) :
Thousands of demonstrators have rallied across Australia to demand greater government action . . .
Did you not know, Aussie PM Kevin Rudd is the modern equivalent of King Canute.
Australia which produces less than 1% of man made greenhouse emissions could go back to the stoneage tomorrow an not make one jot of difference to climate change/global warming even if did exist!

Aron

alexjc38 (01:29:16) :
Just out of curiosity, have any of our close stellar neighbours (e.g., the Alpha Centauri system) also gone into “quiet sun” mode recently?
It was thought some years ago that a survey of ‘sun like’ stars showed that they [and presumably the Sun] spend about a third of the time in ‘quiet mode’. Later research has shown that this ‘result’ may be spurious as the star sample only included a couple of ‘truly’ sun-like stars, the others were more evolved than the Sun. So the bottom line is that we don’t know.

Did any Australian newspapers report these demos? Because I can’t find any articles…

Tenuc

NASA article about a possible connection between sun and earth weather here:-
[URL=http://www.nasa.gov/centers/goddard/news/topstory/2006/space_weather_link.html/URL]

Paul R

John A (02:05:31) :
Did any Australian newspapers report these demos? Because I can’t find any articles…
There was nothing on the evening television news about it, so it must have been a fizzer. They mentioned Swine Flu many times though. ; )

Thanks Leif! I remember reading something about that survey but hadn’t realised that science had moved on a bit since then.

Julian Braggins

For those looking for a new mechanism by which Solar activity affects our climate, see
http://www.thunderbolts.info/forum/phpBB3/viewtopic.php?f=4&t=1861&start=0
This is an interesting mechanism via the Polar Jet Streams, thanks to MG Mirkin. This article in the TPOD of 12 June 09 at
http://www.thunderbolts.info/home.htm
that should be read in conjunction with it, it explains the recent finding of equatorial plasma currents circling the globe

VG

This is quite historic. In conjunction with the quiet sun we have here the cosmic ray count going through the roof (its usually flat} It looks more and more likely that Svensmark was right re cloud and precipitation wouild be nice to see some recent cloud data
http://cosmicrays.oulu.fi/

OT, but a useful riff in the Torygraph about Herschel, crops, sunspots and the Inconvenient Coolerating of the World (ICW).
Linky: http://www.telegraph.co.uk/comment/columnists/christopherbooker/5525933/Crops-under-stress-as-temperatures-fall.html

@ Leif Svalgaard (00:19:34) :
The text in National Geographic is disconnected (chaotic). Total mish-mash.
BTW. A layman’s question. Is there any collation of the most important solar indices (from sci point of view) with attached short comments why they should be concidered together or NOT in making judgements about present and future state of the Sun? That would clarify a little the present state of solar science on WUWT pages. To the advantage of all like me. Thanks.
Regards

jeroen

John F. Hultquist (22:42:34) :
Thousands of demonstrators have rallied across Australia to demand greater government action . . .
I am still waiting for the moment that a Prime minister or other country leader is standing up in front of the crowd and say’s: There is no Global Warming.

King of Cool

Did any Australian newspapers report these demos? Because I can’t find any articles…
Hardly any. Saw it on Sky News:
http://www.skynews.com.au/eco/article.aspx?id=341892
The “thousands” reported by the BBC looked more like a small gathering of movie extras compared to the real thousands in Iran demonstrating after their election.

Thank you so much, Bill Livingston. I appreciate your work and that you share it here. I cannot imagine more fascinating science.
I hope you will continue to keep us updated in the future.

Gary Pearse

Aron (01:54:25) :
“These people don’t care about facts
http://business.timesonline.co.uk/tol/business/specials/rich_list/article5821334.ece
I believe you are wrong about that. The fact is there is a lot of money to be made investing in the green -this is not taking sides, only seeing opportunities.

C Colenaty

Is there information available as to how the sunspot size at the start of cycle 23 compares to that of 24. More specifically, did 23 also start out with a series of tiny sunspots?

King of Cool,
From that amazing article:

Senator Brown told a crowd of more than a thousand people [ri-i-i-i-ght, who counted them?] in Melbourne yesterday, the effects of climate change are already here, killing 300 thousand people every year, and costing billions of dollars in lost agricultural production… there’s no hope for the planet unless the global community reduces greenhouse gases by 40 per cent by 2020… The rally was one of many across the country, where people demanded the planned emissions trading scheme be dropped, in favour of a move from coal-generated power to renewable energy.

Are there no journalists left who will ask questions?? Or are a politician’s words sacred, like a bishop’s, or a witch doctor’s?
Even simple questions like, “Can you tell us how much renewable energy contributes to the total, and how it can replace coal?” And, “Global warming has resulted in a fraction of a degree increase over the past century. How can that small rise, along with a rise in beneficial CO2, result in “lost agricultural production”?
But, no, such questions are not asked. Senator Brown’s comments are reported as if they are final word on the subject; 300 thousand dead from climate change every year [astonishing news – you heard it here first], and “renewable” energy must now replace fossil fuel energy [how, exactly?]
Real journalism sinks further into irrelevance.