As many regular readers know, I’ve pointed out several times the incident of the abrupt and sustained lowering of the Ap Index which occurred in October 2005. The abrupt step change seemed (to me) to be out of place with the data, and the fact that the sun seems so have reestablished at a lower plateau of the Ap index after that event and has not recovered is an anomaly worth investigating.
From the data provided by NOAA’s Space Weather Prediction Center (SWPC) you can see just how little Ap magnetic activity there has been since. Here’s a graph from October 2008 showing the step in october 2005:
click for a larger image
However, some have suggested that this event doesn’t merit attention, and that it is not particularly unusual. I beg to differ. Here’s why.
In mid December I started working with Paul Stanko, who has an active interest in the solar data and saw what I saw in the Ap Index. He did some research and found Ap data that goes back further, all the way to 1932. His source for the data is the SPIDR (Space Physics Interactive Data Resource) which is a division of NOAA’s National Geophysical Data Center (NGDC). He did some data import and put it all into a mult-page Excel spreadsheet which you can access here.
I had planned to do more study of it, but you know how holidays are, lot’s of things to do with that free time. I didn’t get back to looking at it until today, especially after SWPC updated their solar datasets on January 3rd, including the Ap Index. Looking at the data to 1932, it was clear to me that what we are seeing today for levels doesn’t exist in the record.
About the same time, I got an email from David Archibald, showing his graph of the Ap Index, graphed back to 1932. Having two independent sources of confirmation, I’ve decided to post this then. The solar average geomagnetic planetary index, Ap is at its lowest level in 75 years, for the entirety of the record:
Click for a larger image – I’ve added some annotation to the graph provided by Archibald to point out areas of interest and to clarify some aspects of it for the novice reader.
The last time the Ap index was this low was 1933. The December 2008 Ap value of 2, released by SWPC yesterday, has never been this low. (Note: Leif Svalgaard contends this value is erroneous, and that 4.2 is the correct value – either way, it is still lower than 1933) Further, the trend from October 2005 continues to decline after being on a fairly level plateau for two years. It has started a decline again in the last year.
This Ap index is a proxy that tells us that the sun is now quite inactive, and the other indices of sunspot index and 10.7 radio flux also confirm this. The sun is in a full blown funk, and your guess is as good as mine as to when it might pull out of it. So far, predictions by NOAA’s SWPC and NASA’s Hathway have not been near the reality that is being measured.
The starting gate for solar cycle 24 opened ayear ago today, when I announced the first ever cycle 24 sunspot. However in the year since, it has become increasingly clear that the horse hasn’t left the gate, and may very well be lame.
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Paul S (13:23:44) :
I wonder just how much this effect is contributing to the current historic low in the Ap index.
This is easy to quantify: add 25% to the current December values to get ‘an uncontaminated’ number. To correct any given value of ap multiply by (1 + 3*(cos(psi))^2)^(2/3), where ‘psi’ is the angle between the direction to the Sun and the Earth’s dipole axis. See section 7 of http://www.leif.org/research/suipr699.pdf or see http://www.leif.org/research/The%20semiannual%20variation%20of%20great%20geomagnetic%20storms.pdf
tallbloke (14:34:14) :
Are you aware of any previous studies which have taken either of these two periods into account?
The asymmetry has been studied by many people. Scientists would love to discover any laws or regularities so are very creative in analyzing a thing this way or that, up and down, in and out, ad nauseam. Most of time, these researches do not show any effects, and [this is important] no paper is written announcing the null result. Trust me, ‘everything’ has been tried and failed. Null results are only written about if someone else claims a positive result.
So what are the conclusions of your forthcoming paper Leif. Are you going to buck the trend? 😉
tallbloke (02:12:09) :
So what are the conclusions of your forthcoming paper
The paper is on predicting the cycle. The asymmetry is larger when cycles are weak, but that itself is but a weak tendency, so nothing earthshaking.
I’ve downloaded Hathaway’s data and have been fiddling with graphing. On one run I subtracted south from north and then took the absolute value to see asymmetry against overall cycle strength, so I saw the same tendency. As you say, it is fairly weak. Overall the asymmetry is less variant than the total sunspot area variation, so maybe it’s more the other way round: When cycles are weak asymmetry stays roughly the same as in larger cycles.
What I saw as more interesting is a potential longterm periodicity around 170-190 years and a lot of short term swings around 250-300 days. Until I do some fourier analysis it’s just first impressions though.
Interesting data to read; liked very much “tallbloke’s” comments. It would appear that the earth’s magnetic poles reversed suddenly way back when “Neanderthal Man” began to fade away.
Leif Svalgaard (08:08:38) :
tallbloke (02:12:09) :
So what are the conclusions of your forthcoming paper
The paper is on predicting the cycle. The asymmetry is larger when cycles are weak, but that itself is but a weak tendency, so nothing earthshaking.
This might be only a weak tendency, Dr. Svalgaard. but quite interesting due to the developing cycle 24 asymmetry. So far cycle 24 has 5 spot regions in the northern hemisphere and only 1 in the southern hemisphere, according to a graphic by Kevin on http://www.solarcycle24.com . Sounds pretty asymmetric to me! By itself that might not mean much, but taken together with all the other evidence for a weak cycle… one more piece of grist for the weak cycle mill.
There does look to be some evidence that previous grand minima had a tendency for a single hemisphere sunspot activity, or both poles having the same polarity or the Hale cycle not changing polarity. Its early days and the “phase catastrophe” hasnt happened yet. New evidence from Ian Wilson suggests a trigger mechanism for grand minima, since 1700 (and possibly before) every time J+S line up (minor & major) before solar max we have had greatly reduced sunspot activity, this also correlates with the changes in momentum created by N+U being together. If SC24 max is after March 2011 it will fit this criteria.
I have plotted this phenomena on Carl’s graph. The black dots are J+S together, blue is J+S opposed and red is cycle max.
http://landscheidt.auditblogs.com/files/2009/01/ssbscmax2.jpg
Ian’s paper can be accessed here.
http://landscheidt.auditblogs.com/
nobwainer (Geoff Sharp) (18:34:28) :
There does look to be some evidence that previous grand minima had a tendency for a single hemisphere sunspot activity, or both poles having the same polarity or the Hale cycle not changing polarity. Its early days and the “phase catastrophe” hasnt happened yet.
The Hale cycle has changed polarity already.
Leif Svalgaard (19:37:58) :
The Hale cycle has changed polarity already.
Like I said “early days”. It may also stay like it is for 22 yrs.
Leif Svalgaard (19:37:58) :
To be more precise, proxy records taken from the Maunder (as i have shown you before) suggest the Schwabe cycle goes for 22 yrs rather than 11…which would entail a polarity change, but over a longer period than normal….but who knows, it was way too long ago.
We will know this time.
nobwainer (Geoff Sharp) (20:17:32) :
To be more precise, proxy records taken from the Maunder (as i have shown you before) suggest the Schwabe cycle goes for 22 yrs rather than 11
McCracken has recently analyzed the 10Be record for 1428-2004. He expresses the 10Be content as ‘equivalent’ heliospheric magnetic field. Although I don’t like that method, the relative variation from year to year should be OK. http://www.leif.org/research/Cycle-10Be-Maunder-Min.png shows the result. The FFT power spectrum on the right shows that the cycle period was 12.5 years [frequency 0.08/yr]. It is amazing that some old myths gets perpetuated forever.
Similarly Hiroko Miyahara and her colleages [where I was visiting professor once] in “Variation of the Radiocarbon Content of Tree Rings during the Spoerer Minimum” [28th International Cosmic Ray Conference] measured the radiocarbon content of tree rings from the Spoerer Minimum and found that the 11-year period was dominant [FFT peak at 10.9 years].
Leif Svalgaard (21:12:47) :
The FFT power spectrum on the left
Leif Svalgaard (21:12:47) :
The McCracken graph looks to have a 22 yr cycle in it ….But we can throw proxy reports at each other and not get anywhere, they are proxy reports. You have ones showing normal cycles, others show 22 yr cycles. You cant tell us exactly what happened during the Maunder with any absolute certainty with regard to the solar poles, so lets wait and see.
I suspect we will witness some unusual conditions at the poles in the next cycles, but perhaps not a 22yr Schwabe cycle. That might be reserved for grand minima that is triple punched by strong angular momentum….not like the single punch we are most likely heading into.
nobwainer (Geoff Sharp) (22:43:27) :
The McCracken graph looks to have a 22 yr cycle in it
This is where wishful thinking takes over. The FFT power spectrum clearly shows the 12.5 year peak instead. There is no evidence for the ‘phase catastrophe’.
Leif Svalgaard (04:24:28) :
There is no evidence for the ‘phase catastrophe’.
There is evidence for and against a 22yr Schwabe cycle , it just depends which one you choose.
I think you misunderstand the phrase ‘phase catastrophe’. It should be used to describe the overall grand minimum action affecting the Sun. There is multiple causes in theory, one of which is a 22yr Schwabe cycle. “Phase catastrophe” can still occur without a 22yr Schwabe cycle.
nobwainer (Geoff Sharp) (06:41:34) :
There is evidence for and against a 22yr Schwabe cycle , it just depends which one you choose.
I have shown you the latest version of proxies which supersedes all earlier versions. So, let us put this to bed. There is no evidence of a 22-year Schabe cycle. If the two 11-year cycles are slightly different [there are those who think there is a difference between even and odd cycle], that will show up in the power spectrum at 22 years, but this does not mean that the cycles lasted 22 years.
Leif Svalgaard (09:12:45) :
Usoskin disagrees with you.
The Maunder minimum is a representative of grand minima in solar activity (e.g., Eddy, ), when sunspots have almost completely vanished from the solar surface, while the solar wind keeps blowing, although at a reduced pace (Cliver et al., 1998; Usoskin et al., ). There is some uncertainty in the definition of its duration; the “formal” duration is 1645 – 1715 (Eddy, 1976), while its deep phase with the absence of apparent sunspot cyclic activity is often considered as 1645 – 1700, with the low, but very clear, solar cycle of 1700 – 1712 being ascribed to a recovery or transition phase (Usoskin et al.). The Maunder minimum was amazingly well covered (more than 95% of days) by direct sunspot observations (Hoyt and Schatten, 1996), especially in its late phase (Ribes and Nesme-Ribes, ). On the other hand, sunspots appeared rarely (during ∼ 2% of the days) and seemingly sporadically, without an indication of the 11-year cycle (Usoskin and Mursula, 2003). This makes it almost impossible to apply standard methods of time-series analysis to sunspot data during the Maunder minimum (e.g., Frick et al., 1997)). Therefore, special methods such as the distribution of spotless days vs. days with sunspots (e.g., Harvey and White, 1999) or an analysis of sparsely-occurring events (Usoskin et al.,) should be applied in this case. Using these methods, Usoskin et al. have shown that sunspot occurrence during the Maunder minimum was gathered into two large clusters (1652 – 1662 and 1672 – 1689), with the mass centers of these clusters being in 1658 and 1679 – 1680. Together with the sunspot maxima before (1640) and after (1705) the deep Maunder minimum, this implies a dominant 22-year periodicity in sunspot activity throughout the Maunder minimum (Mursula et al., 2001), with a subdominant 11-year cycle emerging towards the end of the Maunder minimum (Ribes and Nesme-Ribes, 1993; Mendoza, 1997; Usoskin et al., ) and becoming dominant again after 1700. Similar behavior of a dominant 22-year cycle and a weak subdominant Schwabe cycle during the Maunder minimum has been found in other indirect solar proxy data: auroral occurrence (Křivský and Pejml, 1988; Schlamminger, 1990; Silverman, 1992) and 14C data (Stuiver and Braziunas, 1993; Kocharov et al., 1995; Peristykh and Damon, 1998; Miyahara et al. ). This is in general agreement with the concept of “immersion” of 11-year cycles during the Maunder minimum (Vitinsky et al.). This concept means that full cycles cannot be resolved and sunspot activity only appears as pulses around cycle-maximum times.
The time behavior of sunspot activity during the Maunder minimum yields the following general scenario (Vitinsky et al., 1986; Ribes and Nesme-Ribes, ; Sokoloff and Nesme-Ribes, 1994Jump To The Next Citation Point; Usoskin et al., 2000, 2001a; Miyahara et al.). Transition from the normal high activity to the deep minimum was sudden (within a few years) without any apparent precursor. A 22-year cycle was dominant in sunspot occurrence during the deep minimum (1645 – 1700), with the subdominant 11-year cycle, which became visible only in the late phase of the Maunder minimum. The 11-year Schwabe cycle started dominating solar activity after 1700. Recovery of sunspot activity from the deep minimum to normal activity was gradual, passing through a period of nearly-linear amplification of the 11-year cycle. It is interesting to note that such a qualitative evolution of a grand minimum is consistent with predictions of the stochastically-forced return map (Charbonneau, ).
Although the Maunder minimum is the only one with available direct sunspot observations, its predecessor, the Spörer minimum from 1450 – 1550, is covered by precise bi-annual measurements of 14C (Miyahara et al.). An analysis of this data (Miyahara et al., 2006a,b) reveals a similar pattern with the dominant 22-year cycle and suppressed 11-year cycle, thus supporting the idea that the above general scenario may be typical for a grand minimum.
A very important feature of sunspot activity during the Maunder minimum was its strong north-south asymmetry, as sunspots were only observed in the southern solar hemisphere during the end of the Maunder minimum (Ribes and Nesme-Ribes, 1993; Sokoloff and Nesme-Ribes, 1994). This observational fact has led to intensive theoretical efforts to explain a significant asymmetry of the sun’s surface magnetic field in the framework of the dynamo concept (see the review by Sokoloff, 2004, and references therein).
nobwainer (Geoff Sharp) (17:46:58) :
Usoskin disagrees with you.
He disagrees with me on many things. The sunspot record is too spotty to analyze during the Maunder Minimum. That is why the 10Be record and the 14C record must be used. And Mayahara’s paper is clear: http://www.stelab.nagoya-u.ac.jp/~kmasuda/C14_km/C14_publ/icrc03_sp.pdf
see Figure 3 and 4. The notion of a 22-year cycle comes from the 11-year cycles being of uneven size. That gives rise to the two smaller side peaks at 23 and 7 years in figure 3. This is a very different phenomenon than a Schwabe cycle of 22-years. Now, you have not defined Schwabe cycle. I’ll define it as a cycle where the Hale polarity law remains valid throughout the cycle and where there is one reversal of polar fields near the middle of the cycle [and no comments about the polar fields fluctuating as they reverse, please – they do this in every cycle].
Leif Svalgaard (19:22:05) :
He disagrees with me on many things.
And he is not the only one….as outlined in the list of papers he refers to.
nobwainer (Geoff Sharp) (04:19:47) :
He disagrees with me on many things.
And he is not the only one….as outlined in the list of papers he refers to.
Most of the papers are just general background and do not specifically say that there was no 11-year cycle.
And Usoskin [like you] misrepresents what the authors actually say.
For example, in referring to Miyahara:
“An analysis of this data (Miyahara et al., 2006a,b) reveals a similar pattern with the dominant 22-year cycle and suppressed 11-year cycle.”
If you actually read Miyahara’s paper [see her Figure 3 and 4] you will see that the strongest peak in the power spectrum is at 11 years, not 22, so no ‘dominant’ 22-year cycle.
Leif Svalgaard (07:06:42) :
Most of the papers are just general background and do not specifically say that there was no 11-year cycle.
The point is that the 22yr cycle exists (supported by many), whether its dominant or not is not important. I stated originally ” there does look to be some evidence” and that is was only proxy as in your case, so we can put it to bed by both agreeing the evidence is weak on both sides and needs to be tested by modern equipment. Whether you and me will be around to do that is doubtful as this phenomenon was not recorded during the Dalton, and is more likely to occur in far stronger grand minima where it is hit by successive “phase catastrophe” or dynamo “shutdowns” or whatever you want to call it. The Sporer and Maunder clearly show a triple hit, the Dalton was a single hit followed later by a very weak episode at SC12 (a not so grand minimum), the upcoming grand minimum looks to be a single hit only.
nobwainer (Geoff Sharp) (17:20:22) :
The point is that the 22yr cycle exists (supported by many),
Your problem may be one of semantics. One of Usokin’s pet ideas is there is a relic solar magnetic field, left over from the birth of the Sun and not maintained by a dynamo and without field reversals. This was a possible idea back when we had the neutrino problem [because it might have distorted the solar interior and decreased the number of neutrinos generated] and before we had helioseismology [which does not show any distortions]. The relic field would modulate the normal 11-year dynamo driven cycle [the Schwabe cycle] in the sense that it would add to one polarity every other cycle when the two magnetic fields were aligned. This would be especially visible when the 11-year cycle was weak during grand minima. The result would be that every other 11-year cycle might be a bit larger. This would masquerade as a 22-year cycle [especially in the presence of noise]. The issue is best illustrated with a figure. http://www.leif.org/research/Synthetic-10-20-year-cycles.png where on the right I have an alternation of high and low 10-year cycles [thus no physical 20-year cycle] that we think reverse polarity every time without any catastrophe of any kind or shutdown of the dynamo. The power spectrum to the right shows the physical 10-year peak and ‘artificial’ 20-year [at frequency 0.10-0.05=0.05] and 6.7-year peaks [at frequency 0.10+0.05=0.15]. Compare this to Figure 3 in Miyahara’s paper.
This is what the data shows, so, again [and it is getting tedious] there is only an ‘eternal’ 11-year cycle that changes polarity every time. The data [Beer’s 10Be and Miyahara’s 14C] is the best we have and are fully consistent with the above. The dynamo does not shut down. It would not get started again if it did. Appeals to poor data and weak evidence won’t work.
Now, the neutrino problem has been solved [the neutrinos have mass and can change ‘kind’] so no relic field is needed and helioseismology shows that the interior is not distorted. Random asymmetries between cycles and between hemispheres do occur as the two dynamos [one in each hemisphere] operate somewhat independently. There are people that see an odd-even asymmetry between cycles with odd cycles being larger than even cycles. Such asymmetry will show as an artificial 22-year cycle [c.f. the plot i just referred to] with ‘dominant 22-year cycle and sub-dominant 11-year cycle’. There is no theoretical justification [nor observational evidence] for a shutdown of the dynamo. Lots of wishful thinking, though, by many people.
Anthony, it might be coincidence but satellite images of Arctic Ocean from 1979 to date on 31st DEc of each year show snow cover of the northern part of northern Hemisphere after the drop in Ap
Anthony,
you might want to look at http//www.john-daly.com/solar/solar.htm where there is a paper by Dr. Theodore Landscheidt. If you take Fig.3 and add info for cycles 22 & 23 to graph you get very interesting graph!!!