Another anemic solar cycle 23 sunspeck, could 19th century astronomers have seen it?
From Spaceweather.com
SUNSPOT 1016: A ring-shaped sunspot numbered 1016 has emerged near the sun’s equator. Its magnetic polarity identifies it as a member of old Solar Cycle 23. Until these old cycle sunspots go away, the next solar cycle will remain in abeyance.
Leif Svalgaard (11:08:54)
Hmmm…. Leif Svalgaard is banned by Tamino but TCO still enters almost 1/5 of all the comments. Interesting world we live in.
Leif Svalgaard (07:57:16) :
Geoff Sharp (05:28:58) :
The current doppler images show how long SC23 will go…sunspots are tied to the differential flows and SC23 shows scope for more sunspots to come.
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The current Doppler images etc have nothing to do with this [and if anything, the torsional oscillation is a consequence of the activity, not the cause of it]. Every solar cycle drags on for some time after the official minimum.
Interesting comment….The slower regions are produced at the Tachocline and rise to the surface, separating and stretching in the process due to the Sun’s angular momentum from rotation. Could you explain how the sunspot cycle has a hand in this process of forming the torsional oscillation bands.
rephelan (16:37:15) :
Hmmm…. Leif Svalgaard is banned by Tamino but TCO still enters almost 1/5 of all the comments. Interesting world we live in.
Perhaps because my insightful and penetrating analyses were seen by tamino to be a much greater threat than TCO’s 🙂
Geoff Sharp (17:54:57) :
Could you explain how the sunspot cycle has a hand in this process of forming the torsional oscillation bands.
It seems that with you I have to explain everything several times over:-)
One of the better models is by Spruit:
Origin of the torsional oscillation pattern of solar rotation
H.C. Spruit (Submitted on 9 Sep 2002 (v1), last revised 19 Oct 2002 (this version, v2))
A model is presented that explains the `torsional oscillation’ pattern of deviations in the solar rotation rate as a geostrophic flow. The flow is driven by temperature variations near the surface due to the enhanced emission of radiation by the small scale magnetic field. The model explains the sign of the flow, its amplitude and the fact that the maxima occur near the boundaries of the main activity belts. The amplitude of the flow decreases with depth from its maximum at the surface but penetrates over much of the depth of the convection zone, in agreement with the data from helioseismology. It predicts that the flow is axisymmetric only on average, and in reality consists of a superposition of circulations around areas of enhanced magnetic activity. It must be accompanied by a meridional flow component, which declines more rapidly with depth.
Paper here: http://arxiv.org/abs/astro-ph/0209146
Leif Svalgaard (18:32:40) :
It seems that with you I have to explain everything several times over:-)
I dont recall discussing this precise question before, perhaps you could enlighten me or maybe its an attempt at humor?
Spruit’s model is another interesting observation, but it is just that and cannot be stated as fact. To suggest surface variations are driving this oscillation to the tachocline seems at odds with Dr. Howes work.
Another observation is the oscillations are created at the tachocline in the shear layer between the convective and radiative zones from torque applied from acceleration and deceleration (explaining polarity changes). This extends and breaks up on its way to the top of the convective zone until we get the observed patterns and lays the ground work for future sunspots. This theory could be disproved if the Sun or the core was shown to be completely static. On the small amount of data I have been able to find, it does suggest the Sun’s rotation rate does vary?
http://users.beagle.com.au/geoffsharp/howefig25.png
http://users.beagle.com.au/geoffsharp/comb2.gif
thanks to a moderator for correcting my typos.
Reply: de nada. ~dbs
Geoff Sharp (19:44:15) :
I dont recall discussing this precise question before, perhaps you could enlighten me or maybe its an attempt at humor?
I have pointed out many times that the TO is the result of activity, not the cause of it. It is not funny to have to state this important fact again and again. If you want to be taken seriously, perhaps you should stop the comedy act.
To suggest surface variations are driving this oscillation to the tachocline seems at odds with Dr. Howes work.
Spruit and other’s explanations are theoretical understanding, not observations. The actual data is not good enough to discriminate which way it goes.
Another observation is the oscillations are created at the tachocline in the shear layer between the convective and radiative zones from torque applied from acceleration and deceleration (explaining polarity changes).
This is not observation, but speculation. Perhaps explain how the polarity changes…
We have ourselves studied this problem, e.g. http://www.leif.org/research/ast10867.pdf
Both the observations and the theory are still incomplete, but there is general convergence of thought as to the importance of the magnetic field and/or temperature variations acting back on the flow. Section 8.5 of http://solarphysics.livingreviews.org/Articles/lrsp-2005-1/ has more on this.
There is little, if any, evidence that the TO is driving the solar cycle.
Leif Svalgaard (20:53:38) :
Like I said i dont recall such discussions, maybe you had them with someone else.
All we have is observations, theory and speculation and Spruit’s paper is extremely speculative and is full of weasel words. To put this paper forward as some sort of evidence that TO is a product of the sunspot cycle is not convincing.
I would think a better method would be to accept the gaping hole of knowledge in this area and not discount other theories unless obviously flawed.
In my speculation I suggest the the polarity change comes about by the magnetic fields created at the tachocline, change occurring on the deceleration/acceleration change over. But it all comes down to rotation rates of the Sun which seems hard to come by (or could be an internal rotation of the core). This is an area of science not well catered for, which surprises me as it would answer many questions.
What is happening with the solar rotation rate???
Geoff Sharp (22:12:47) :
Like I said i dont recall such discussions…
March 9th, 2009 Solarcycle24.com
Spruit’s paper is extremely speculative and is full of weasel words..
I just re-read Spruit’s paper. Spruit is one of the World’s foremost investigators of solar motions and convection. His work carries great weight. To get a feeling for his work: http://adsabs.harvard.edu/cgi-bin/nph-basic_connect?qsearch=spruit&version=1
The paper is not speculative. On the contrary it is quantitative and makes detailed predictions, most are which match the meager data we have. ‘Weasel words’ are normal in this kind of work, and are not meant as a way of ‘weaseling out’. The paper makes very detailed and testable predictions.
In my speculation I suggest the polarity change comes about by the magnetic fields created at the tachocline, change occurring on the deceleration/acceleration change over.
This is no explanation at all. How does the change over ‘change the polarity’, and the ‘polarity’ of what?
But it all comes down to rotation rates of the Sun which seems hard to come by…[…]
What is happening with the solar rotation rate???
And again, the TO has little to do with the rotation or its rate. The TO is a zonal flow, a narrow ‘wind’ or ‘jet’, like the jet stream in the Earth’s atmosphere.
The clearest clue is that the energy in the flow is much, much smaller than the energy in the magnetic field it is supposed to create or control. The tail wagging the dog it would be.
Leif Svalgaard (23:00:13) :
March the 9th you made 4 statements….but there was no discussion.
1: the Doppler images do not show solar rotation, but ‘zonal flows’ i.e. winds in the atmosphere.
2: the low-latitude sunspots of cycle 23 help generate the faster flow
3: the wind is a consequence of solar activity, not the cause of it.
4: explain to us how the angular momentum disturbance would cause the wind in such a narrow belt, or the wind at all.
Point 3 being the total of the discussion.
Spruit’s paper in his intro uses the word “could” 7 times. You might hold him in high regard but his paper is nothing but unproved theory. I would prefer to hedge my bets on this one.
The clearest clue is that the energy in the flow is much, much smaller than the energy in the magnetic field it is supposed to create or control. The tail wagging the dog it would be.
It is also very likely that a lot of the flow strength has dissipated by the time it reaches the surface (2 years later) but retains it magnetic properties. But lets see if we can get an answer to my previous question.
What is happening with the solar rotation rate???
Leif Svalgaard (23:00:13) :
March the 9th you made 4 statements….but there was no discussion.
1: the Doppler images do not show solar rotation, but ‘zonal flows’ i.e. winds in the atmosphere.
2: the low-latitude sunspots of cycle 23 help generate the faster flow
3: the wind is a consequence of solar activity, not the cause of it.
4: explain to us how the angular momentum disturbance would cause the wind in such a narrow belt, or the wind at all.
Point 3 being the total of the discussion.
Spruit’s paper in his intro uses the word “could” 7 times. You might hold him in high regard but his paper is nothing but unproved theory. I would prefer to hedge my bets on this one.
The clearest clue is that the energy in the flow is much, much smaller than the energy in the magnetic field it is supposed to create or control. The tail wagging the dog it would be.
It is also very likely that a lot of the flow strength has dissipated by the time it reaches the surface (2 years later) but retains it magnetic properties. But lets see if we can get an answer to my previous question.
What is happening with the solar rotation rate???
Am late as usual but I had to mention this. Seems that the Belgium spot counters are worried about the lack of spots so they added the two un-numbered specks on the 6th and 22nd to their count!!! That puts 25 spotless days in April, 105 this year and 616 this lull.
Geoff Sharp (23:52:51) :
What is happening with the solar rotation rate???
Is anything happening?
Leif Svalgaard (06:06:39) :
Geoff Sharp (23:52:51) :
What is happening with the solar rotation rate???
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Is anything happening?
Apart from you ducking the question I am not too sure. There does not look to be too much information in this area….was hoping with your incredible knowledge you could inform?
Geoff Sharp (06:48:15) :
Apart from you ducking the question I am not too sure. There does not look to be too much information in this area….was hoping with your incredible knowledge you could inform?
I never duck a question. Nothing is happening. Can’t inform on nothing.
Geoff Sharp (06:48:15) :
Apart from you ducking the question I am not too sure.
Reanalysis of MDI data shows a significantly slower TO during solar cycle 23, but since the TO [zonal flows or winds] has nothing to do with the the rotation rate, it is fair to say that nothing is happening with the rotation rate.
Leif Svalgaard (07:28:47) :
Geoff Sharp (06:48:15) :
Apart from you ducking the question I am not too sure.
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Reanalysis of MDI data shows a significantly slower TO during solar cycle 23, but since the TO [zonal flows or winds] has nothing to do with the the rotation rate, it is fair to say that nothing is happening with the rotation rate.
That is your (and others) speculation. Zonal flows might have nothing to do with rotation rate. But the interesting point is that we have a “confirmed” change of rotation of the Sun. If this is the case like the earth/moon system there must be a trade off in relation to conserving angular momentum….this should be able to be determined.
Do you have a link for the SC23 rotation reanalysis?
Today is May 4
I looked at the current sunspot graphic on the home page and said “aha! finally a well-defined sunspot has appeared!”
then I realized it was a dark speck on my laptop screen. Perhaps a piece of cookie.
Leif Svalgaard (07:15:32) :
Geoff Sharp (06:48:15) :
Apart from you ducking the question I am not too sure. There does not look to be too much information in this area….was hoping with your incredible knowledge you could inform?
I never duck a question. Nothing is happening. Can’t inform on nothing.
And yet a paper you co produced states otherwise….I am confused.
http://www.leif.org/research/ast10867.pdf
Geoff Sharp (16:15:18) :
But the interesting point is that we have a “confirmed” change of rotation of the Sun.
Nobody has ever said that. The TO that Howe shows is not ‘the rotation of the Sun’, no matter how many times you repeat it is.
Do you have a link for the SC23 rotation reanalysis?
Of course. Page 3 of http://leif.org/research/SolarCycleMinima.ppt shows Howe’s re-analysis. Beware that these measurements are difficult.
So,
1) not rotation
2) no good evidence TO has changed, if anything decreased
3) “case like the earth/moon system”: the E/M system works with a one-way coupling that always slow down the Earth, and can never speed the Earth up.
Leif Svalgaard (17:29:39) :
You are all over the place on this one.
First you state:
Reanalysis of MDI data shows a significantly slower TO during solar cycle 23
Then once questioned on the data thats looks weak you state:
no good evidence TO has changed, if anything decreased
When questioned on the solar rotation rate you say there has been none and try to confuse the issue by involving differential rotation, but a paper produced by yourself states in the conclusion:
“A secular deceleration of the mean solar rotation in the 20th
century was found by tracing sunspot groups. This variation
also shows a finer modulation indicating a connection
with the phase of the 11-year solar cycle. In the years 1902
and 1913 we have found possible rotational signatures of
two weak solar activity cycles (Gleissberg minimum). The
rotation velocity residual increased in these years for about
0.4 ◦/day. This is in a qualitative and quantitative agreement
with a similar rotational behaviour during the Maunderminimum.
A qualitatively similar behaviour was also found on
a shorter time scale for the period 1998–2000. As solar activity
was increasing, the equatorial rotation velocity determined
tracing coronal bright points was decreasing (in this
part of analysis monthly values were used).
A dependence of the solar rotation velocity measured by
magnetic tracers and solar activity and interplanetary magnetic
field was found. An interplay between the Reynolds
and the Maxwell stresses is proposed for the interpretation.
As stated by R¨udiger & Hollerbach (2004), the more magnetic
the Sun is, more rigid is its rotation.”
This paper also shows graphs of rotation change and includes a graph of sidereal equation rotation speed changes.
http://www.leif.org/research/ast10867.pdf
You have also had quite a bit do with a paper by J K Lawrence
Rotational quasi periodicities and the Sun – heliosphere connection, where if I am not mistaken they produce fluctuating solar rotation periods determined from the IMF.
On Solarcycle24.com you responded to a question from “atra” on the 4th May (Oz time):
“Is it possible that weak cycles and grand minimums are related to solar rotation, mainly the slowing down of the equatorial rotation?
Is there any data on this?”
Your Answer:
“Whatever data we have suggests that solar rotation is faster when activity is low, i.e. that solar activity slows down solar rotation. E.g. Figure 2 of http://www.leif.org/research/ast10867.pdf”
I find this all very confusing and if the mentioned papers are only taking about differential rotation then they are very badly written and should be considered misleading. “atra’s” question does not look to be addressing differential rotation.
Geoff Sharp (20:30:52) :
You are all over the place on this one.
As you point out the terminology is confusing. And several authors [including some of my co-authors] contribute to the confusion. Some of this is historical. Terms often survive past their ‘sell-by date’. My recent comments were an attempt to cut through the maze and haze and set things straight. Give you the right terminology to use.
Wrong [or sloppy] terminology abounds. E.g. one talks about ‘superrotation’ of the Venusian upper atmosphere, it ‘rotates’ 60 [sixty!] times faster than the solid planet. This is clearly not rotation, but a superfast wind. A current suggested explanation goes something like this: the superrotation is produced by interaction between meridional circulation and planetary-scale waves. Thermally induced waves produce equatorward momentum fluxes in the middle atmosphere, while the planetary-scale pattern of two different gravity and Rossby waves with the same frequency is found to produce the equatorward momentum flux in the lower atmosphere.
Similar processes probably take place in the Sun, except on a much smaller scale [speed-wise, that is].
Leif Svalgaard (22:12:30) :
I am still confused, maybe we need to coin a new phrase to cut thru the haze. I am looking for data on the whole mass of the Sun in relation to rotation speed, how long it takes to do a complete revolution at the equator as viewed from the Sun showing any variance over time….lets call this “Overall Solar Rotation Velocity”.
What type of rotation are you referring to in the paper:
http://www.leif.org/research/ast10867.pdf
A secular deceleration of the mean solar rotation in the 20th
century
Also what type of rotation is shown in the graphs in that paper.
Is the paper by J K Lawrence
Rotational quasi periodicities and the Sun – heliosphere connection, talking about overall solar rotation or something different?
http://arxiv.org/abs/0803.3260v1
Geoff Sharp (23:40:28) :
I am looking for data on the whole mass of the Sun in relation to rotation speed, how long it takes to do a complete revolution at the equator as viewed from the Sun showing any variance over time….lets call this “Overall Solar Rotation Velocity”.
Since most of the solar mass resides in the core, that would be close to the rotation of the core, but since the speed depends on position you have to integrate the rotational profile weighted by mass to get am ‘average’ rotation. Nobody really cares much for what the precise result is, so you won’t find a handy number anywhere.
What type of rotation are you referring to in the paper:
http://www.leif.org/research/ast10867.pdf
The residuals are the deviation from the average rotation period integrated over all latitudes. If the differential rotation was the same over time, this difference would be zero. A larger number means a stronger differential rotation, not really that the whole sun is rotating faster.
Is the paper by J K Lawrence
Rotational quasi periodicities and the Sun – heliosphere connection, talking about overall solar rotation or something different?
That is the ‘recurrence period’ of magnetic activity which might be close to the rotation period at the location where the magnetic field is generated or located. This may not be the same as the rotational period of the non-magnetic parts of the Sun.
Since there is a [historically based] tendency to call all of these ‘rotation’ even if only referring to ‘wind’ speeds, there are fertile grounds for confusion of the ‘uninitiated’. It should be clear from the context what is what, though. To calculate the total angular momentum you integrate the product of mass and speed over all locations. That number will slowly decrease over time [eons] due to magnetic ‘friction’ with the solar wind but cannot otherwise vary, so the precise number is of little interest. An approximate value is easy the get, e.g. as here: http://physics.ucsd.edu/students/courses/fall2002/physics1a/homework/1AHW7Sub.html
Leif Svalgaard (04:44:06) :
I get your drift…overall solar rotation velocity is not something easy to measure.
Geoff Sharp (05:05:01) :
I get your drift…overall solar rotation velocity is not something easy to measure.
Especially not when one mixes concepts and not keep a clear distinction [and many of us are sinners in that regard] between ‘rotation’ and ‘flows’ or ‘winds’.
A recent review of all this is here:
Large Scale Flows in the Solar Convection Zone
Brun, Allan Sacha; Rempel, Matthias
Space Science Reviews, Volume 144, Issue 1-4, pp. 151-173
Publication Date:04/2009
Keywords: convection, rotation, mean flows, magnetism, torsional oscillations
DOI: 10.1007/s11214-008-9454-9
Abstract
We discuss the current theoretical understanding of the large scale flows observed in the solar convection zone, namely the differential rotation and meridional circulation. Based on multi-D numerical simulations we describe which physical processes are at the origin of these large scale flows, how they are maintained and what sets their unique profiles. We also discuss how dynamo generated magnetic field may influence such a delicate dynamical balance and lead to a temporal modulation of the amplitude and profiles of the solar large scale flows.