UPDATE: The SWPC press conference audio is now available, hear it here
Shortly after SWPC dropped on their website their still invisible “press conference” ( I have yet to get the link to audio, even though requested twice from Doug Biesecker) Leif Svalgaard remarked that the 10.7 cm radio flux graph produced by SWPC in that announcement on their web page was “just wrong”.
After spending months as a regular supporting commenter, Leif asked if he could write a guest post about it. After several microseconds of uncertainty, I said “yes”. So for the first time ever on WUWT, I present Dr. Leif Svalgaard as guest author, rather than commenter. – Anthony
The Solar Radio Microwave Flux
Guest Post by Leif Svalgaard, May 2009
(A PDF of this essay is available here)
Since 1947 we have routinely measured the flux of microwaves from the Sun at wavelengths between 3 and 30 cm [frequencies between 10 and 1 GHz]. This emission comes from high in the Chromosphere and low in the Corona and has two different sources [although there is debate about their relative importance]: thermal bremsstrahlung [due to electrons radiating when changing direction by being deflected by other charged particles] and ‘gyro’-radiation [due to electrons radiating when changing direction by gyrating around magnetic field lines]. These mechanisms give rise to enhanced radiation when the temperature, density, and magnetic field are enhanced, so the microwave radiation is a good ‘measure’ of ‘general’ solar activity. As strong magnetic fields are located in specific regions that can live for weeks and often reoccur at or near the same location for months [perhaps even years], there is a strong rotational signal in the emission superposed on a solar cycle variation of a ‘background’ activity level. At solar minimum, especially a ‘deep’ one as we now experiencing, the effect of active regions largely disappears and we observe a sort of solar ‘ground state’.
As the radio flux measurements [as opposed to the sunspot number] are unaffected by changes of [human] observers and their observing techniques and instrumental and atmospheric differences they may be a ‘truer’ and more objective measure of solar activity [to the extent that we can reduce this complex concept to a single number per day] and the many decades-long flux record could throw light on the important issue of the long-term variation of solar activity. The solar microwave flux is nominally an absolute flux, one solar flux unit defined as [the very small amount of] 10-22 Watt per square meter per Hertz. Making an absolute measurement is always difficult and considerable uncertainty and debate surrounded these measurements early on, before being settled by international cooperative work in the late 1960s [Tanaka et al., Solar Phys. 29 (1973) p. 243-262; http://www.leif.org/research/Tanaka-Calibration-F107.pdf]. By observing the radio flux from supernova remnants [Cassiopeia-A, Cygnus-A, and Virgo-A] one can verify the constancy of the calibration.
The longest running series of observations is that of the 10.7 cm [2800 MHz] flux [often simply referred to as ‘F10.7’] started by Covington in Ottawa, Canada in April 1947 and maintained to this day[and hopefully much longer] at Penticton site in British Columbia [http://www.hia-iha.nrc-cnrc.gc.ca/drao/solar_e.html]. The data is available from several sources, e.g. from the NGDC at http://www.ngdc.noaa.gov/stp/SOLAR/FLUX/flux.html, more timely at ftp://ftp.geolab.nrcan.gc.ca/data/solar_flux/daily_flux_values/current.txt. There are three measurements per day with small systematic [and poorly understood] differences. One can either average all three, or as in this work only use the noon value [for Penticton at 20:00 UT, since 1991].
As with all solar indices, there is the issue of the varying distance between the Earth and the Sun. For describing the effect on the Earth’s atmosphere and environment the proper values of the indices to use should, of course, be the ones observed at the Earth, but for studying the Sun, those values must be adjusted to the mean distance [at 1 astronomical unit]. This is not always appreciated and one sees endless discussions about F10.7 changes or flat-lining without the 7% change caused by the varying distance being taken into account. Needless to say, here we use the ‘adjusted flux’.
So, what does the record look like? Figure 1 shows the entire record up to date of writing [14 May, 2009], plotting the ~23,000 daily noon values [pink curve] and a running 27-day mean [black curve]:
The solar cycle variation is obvious, but so is another fact: [highlighted by the green box] that the flux at every minimum is very nearly the same. There has been no clear systematic variation or trend in the ‘ground state’. Figure 2 shows the 1954 minimum overlaid the current minimum, and is a rather dramatic demonstration of the constancy of the ground state (also shows nicely the 27-day recurrence tendency):
Other observatories have long and continuing series of measurements of the microwave flux. Of note is the long series from Japan (Toyokawa 1951 Nov – 1994 Apr; Nobeyama 1994 May – present) at several wavelengths around the 10.7 cm (e.g. 3.75 GHz = 8 cm; 2 GHz = 15 cm; and 1 GHz = 30 cm). The fluxes at these wavelengths are highly correlated with each other. Figure 3 shows the correlation of 3.75 GHz versus 2 GHz:
This means that we can use the regression equations to put all the measurements on the same scale, scaling [marked with an asterisk] them to 3.75 GHz (Figure 4):
This looks very much like Figure 1 [the coefficient of determination of the correlation with F10.7 is as high as R2 = 0.987, which is a welcome finding as one observatory series then supports the other, at least to the accuracy of the scatter plot]. Scaling the average of the Japanese [scaled] observations to F10.7 we obtain (Figure 5):
If you look very closely, you might see that the red curve (Japanese stations) lies a little bit below the green curve (Canadian stations) before 1991 and a little bit above the green curve thereafter. Here is a plot of the ratio of the flux values of the two series (Figure 6) with different colored symbol for the Ottawa and Penticton data:
. Figure 7, above. In any event, the change is but small.”]
Adding 3% to the Ottawa flux before 1991, rescaling the Japanese measurements to the thus corrected Canadian series, and computing the average flux from the two series gives us the composite series shown in Figure 8 below. All of these adjustments are very small, though, and do not substantially alter any conclusions drawn from the measurements. Although the microwave flux measurements are said to be absolute, a further correction [multiplication by the ‘URSI’-factor of 0.9] is required to get the ‘real flux’. We shall ignore that constant factor as only the relative variation is of interest here.
The red and green curves in the composite graph show the Canadian and [scaled] Japanese series going into the composite. On the whole, there is substantial agreement and the microwave flux seems well-determined.
One can now ask how this measure of solar activity compares to other measures, in particular the sunspot number [the Wolf Number]. Anticipating a finding described later, we correlate the sunspot number against the F10.7 flux (Figure 9) for the interval 1951-1988, and obtain a purely formal polynomial fit [as the relationship is not quite linear]:
The fit is good (R2 = 0.977) up until ~1989.0 after which time the observed sunspot number falls progressively below the fitted number (Figure 10):
To quantify the drift we divide the observed sunspot number by the fitted one. When the sunspot number is very low [near minimum, marked by m; worst case, zero] that quotient becomes very noisy or meaningless, so we plot only cases where the sunspot number was above 5 (Figure 11):
The progressive drift is much larger than the 3% correction and is therefore not due to the correction. It seems inescapable that the relation between the sunspot number and the microwave flux has changed significantly in recent years. Another way of showing this is Figure 12:
Ken Tapping has come to a similar conclusion (from the 2009 Space Weather Workshop: http://www.fin.ucar.edu/UCARVSP/spaceweather/abstract_view.php?recid=995):
“The Changing Relationship between Sunspot Number and F10.7”: Sunspot Number and the 10.7cm solar radio flux are the most widely-used indices of solar activity. Despite their differing nature and origins at different places in the Sun, these two indices are highly-correlated to the point where one can be used as a proxy for the other. However, during Solar Activity Cycle 23 we started to see a small but definite change in this relationship…”
So far we have been on the [relatively] firm ground of data analysis, but when it comes to an explanation of the changed relationship, we enter the realm of pure speculation [for now]. Three obvious hypotheses present themselves:
1) The sunspot counting procedure or observers have changed with resulting artificial changes of the sunspot number as they have in the past.
2) Changes in the Corona or Chromosphere accounting for additional F10.7 emission.
3) Livingston & Penn’s observations [http://www.iop.org/EJ/article/1538-4357/649/1/L45/20946.web.pdf?request-id=e22b7626-e93b-4ce3-b6f1-a999655b8888] that the sunspots are getting warmer during the last decade, leading to a decreased contrast with the surrounding photosphere and hence lessened visibility, possibly resulting in an undercount of sunspots.
There has been some criticism of SIDC and SWPC recently related to counting small pores, changing the count inexplicably, and various mistakes, but it seems to this writer that these problems would not be serious enough to account for the continuous and progressive drift shown in Figure 11. The near constancy of the flux at minima since 1954 argues against a change of the physical conditions at the source locations, leaving the exciting possibility that Livingston & Penn may be correct.
Is 38 years enough to say there is a correlation between Sunspot Number and F10.7? How do we know those 38 years weren’t the anomaly? Maybe when F10.7 flux and sunspot activity align it creates a forcing effect. Are scientists confident enough to say that variations in F10.7 are the result of sunspot activity?
If the correlation is correct but sunspots are getting warmer and decreased contrast is leading to undercounting, what does that mean? Is it the same thing that happened in previous minimums? Bottom line, are we getting warmer or colder?
Walt Stone (03:24:01) :
Yep Walt I agree too. Thanks Leif , some very thought-provoking ideas and insights
Great article, Leif.
If sunspots are a bit warmer, does it follow that the sun as a whole will also be warmer? Or could warm sunspots indicate a sun that overall is less active? We presently think of the Maunder minimum as a time when the sun was cooler, as marked by Be10 and C14 proxies, vs. the Medieval Warm period. Should we revise our thinking? Are the Be and C proxies no longer valid for some reason?
Thanks for the great article Leif, interesting stuff indeed.
I have one question along a similar theme as some other posts here. If the Sunspots are getting brighter, presumably they are hotter. Would this have an impact on the angular momentum of the Sun (my naive thinking using a convection analogy: hotter=lower density). That is, would it be reflected in a higher/lower rotation rate of the outer layers – can we measure this?
rbateman (03:58:36) :
ralph ellis (02:02:48) :
“You need an image processing program. Take the GONG images and apply an exponential stretch, or something similar. Your jpeg scale is 0 to 255. You need to highlight differences of 10 or less in greyscale.
Pixels of 237 are not normally distinguishable from adjacent pixels of 244, 255 being totally white, 0 being black.
And even at that, 1.029 to 1 is a poor contrast even when stretched.”
200 years ago a solar observer could not have done that!
These “pinpricks” as Ralph calls them, appear to be very tiny and brown in colour, not your typical black… the only black spots are the dead pixels and dust on the PC screen…
What was the average image diameter of the sun projected on paper by a telescope in the 1850s? Our modern images are large and our instruments can zoom in on extra detail.
Leif Svalgaard (21:30:10) :
Bill Yarber (21:16:53) :
1) What changed in the instrumentation or the method used to detect and/or count sun spots in 1989?
Nothing we know off. And I don’t think anything changed
If you run Carsten A.Arnholm software “Solar Simulator 2” you´ll see what happened: The Sun changing direction around the barycenter.
“solar motion, volcanic activity, and climate, 1990-2000.” Author James Shirley suggests that the coming decade may be marked by climatic extremes, and postulates unusual solar motion as the cause of increased volcanic activity which will contribute to the weather extremes. According to Shirley, through the years 1989 to 1991, the Sun’s motion will be retrograde relative to the solar system mass center.”
deadwood (22:55:18) :
Thanks Dr. Svalgaard. Just enough dumbing down for this geologist to (mostly) follow.
One question: Do you think the change in slope of tail of cycle 23 have any connection to the apparent changes in the nature of sunspots? And if so, what would be your explanation.
deadwood,
The descending part of Cycle 23 was clearly telling us that we were headed toward a quieter Cycle 24 which many of us, or at least the planetary relationship believers, already knew about.
The explosive nature of the declining part of Cycle 23, as in stronger proton flaring etc…, was interrelated with the overall nomenclature of the solar magnetic field. The polar readings were considerably weaker than what they should have been and this was a clear telling sign of how the cycle to cycle transition was not behaving as usual. If you can use the term usual with as little data as we have.
And just to throw out some common sense which might bug some of the more astute “science people”. The solar cycle is related the changing interacting relationship between the poles. This is why we see it behave somewhat like an accordian’s movement (tilted), with the stronger polar magnetic field readings preceding the stronger lower latitude readings, sunspots , C-Holes ( Or Stanford Mean Readings).
Now we know that when the polar strength becomes equal we increase the chances of solar eruptions, coronal holes. So coronal holes are part of the solar cycle development process. And this is why Jack Eddy found out that there was an absence of the northern lights during the Maunder Minimum.
Because the coronal holes had to have disappeared. At least for a while at the lower latitudes. And this is why I believe that my thoughts from as far back as fifteen years ago are correct. That this minimum will be slightly stronger than the Dalton Minimum because we are still seeing the presence of coronal holes. So Cycle 24 will not be a Maunder Minimum like cycle.
And the latter was most likely preceded by a time when the polar field strength was stuck in a much higher continual state, not a much lower state. Even if the current exact opposite state is having a diminishing effect upon the upcoming cycle itself.
James Shirley works, links:
http://www.giurfa.com/james_shirley.pdf
http://www.giurfa.com/james_shirley_minima.pdf
Thank you, Dr. Svalgaard. I read here often that many ascribe to your view of solar variability. (Or perhaps I’m inferring this incorrectly) Does a summary of your view of cause for the warming/cooling of climate exist, or will you post it here?
Dr. Svalgaard,
Thankyou for your professional demeanor and above all, your patience.
Two points of interest: Ref. Fig 11 composite.
1. To my eye there appears to be a different noise signature (periodicy-frequency) in the 19-21 solar cycle envelopes as compared to the cycle 22-23 envelopes. Any comments?
2. The morphology (Shape) of the 22-23 envelope peaks is less coherent (unstable?). Again any comment would be appreciated
Are these type of metrics considered for measurements of solar systemic parameters?
Regards,
J. D. Lindskog CPO (SS)
USN (Retired)
Leif Svalgaard, yes, please. Another and another article. Thanks to you and Anthony and WUWT commenters for a uniquely informative blog.
I especially enjoyed contemplating the possibiliy that: “the sunspots are getting warmer during the last decade, leading to a decreased contrast with the surrounding photosphere and hence lessened visibility, possibly resulting in an undercount of sunspots.” This idea points us more towards rethinking the TSI during the Maunder Minimum–and, even better, suggests more articles on the complexity of our climate sysem. What does Earth do with all that TSI? It’s not enough anymore to simply shout out for sunspots– or the sun as the “driver” of climate. It might be the fuel, richer or leaner at times, but the car’s engineering and its various drivers tell us much more about its performance.
Superb Dr. Svalgaard.
So, if I’m reading this correctly, I could be correct than when I half-jokingly referred to SC24 as the Plage Cycle, and that the difference in SC23 between F10.7 values and spots observed and counted might have been a precursor of what we’ll see (or not see) in SC24. By that I mean that in SC24 the values in F10.7 could be much higher than (observed) sunspots.
Leif
Thanks for excellent insightful article.
In “GLOBAL EARTH SURFACE TEMPERATURE CHANGES INDUCED BY MEAN SUN
DYNAMO MAGNETIC FIELD VARIATIONS”, Silvia Duhau states:
Anthony
May I encourage finding an expert to post a similar article on the sun’s magnetic field variations.
Leif
Your showing the green minimum line in the composite F10.7 graph, coupled with Duhau’s article raised the following question:
Does the integral of F10.7 above your green minimum line to F10.7 correlate with corresponding integrated thermal changes in earth’s ocean and atmosphere about the average?
Per Adolfo Giurfa’s comment,
Nicola Scafetta proposes a model of solar activity on earth’s climate/ temperature driven by variations in the sun’s motion around the solar system center of mass. See Scafetta’s presentation to EPA, especially slides 65, 66.
“Climate Change and Its causes: A Discussion about Some Key Issues” N. Scafetta. Invited author at the U. S. Environmental Protection Agency, DC USA, February 26, 2009. video
Slides
I’m not sure if I would call the fact the Livingston & Penn may be correct ‘exciting’. I’m hoping they are not correct, I have no desire to enter a Maunder type minimum during my declining years. It’s bad enough that the Mayan/Olmec end of the next 52,000 years cycle is about a month after I’m supposed to retire, but thinking that my retirement may end up being in a new ‘little ice age’ is not pleasant.
Maybe the new sunspot is:
http://www.thesun.co.uk/sol/homepage/news/article2431157.ece
Amazing picture none the less. Thanks for this great article guest piece Lief. Well done and keep it coming.
Very nice.
Which is the better indicator of natural variation in TSI — SSN or 10.7 cm flux?
Or what about CR flux?
Of course, we can measure these directly — now — but in terms of historical sun-climate relations it might be useful to know this. For instance, and please do correct me if I’m wrong, but your historical TSI series is based, if I’m not mistaken, upon SSN. Now I know you’ve adjusted historical SSN’s, but haven’t looked into how you did it, e.g. whether 10.7 cm flux was involved. So maybe you’ve done all this already, but I was just thinking that if 10.7 cm flux is a better indicator of TSI than SSN, then using it somehow in calibrating/correlating the main historical record we have — SSN, at least as far as human observed data is concerned — would seem an obvious thing to consider.
Again, very nice. I especially noted your observation about where the data analysis ended, and the speculation began.
Thanks Leif,
Great article. Let’s keep monitoring the F10.7 radio flux to see if it continues rising as expected (seems to be).
I guess the good thing is that there is going to be a solar cycle 24 after all and we are not looking at the cold of the 1690s.
I like this comment and the two new very active regions on the Sun (producing barely visible sunspots despite being more active than anything seen in a few years now) seem to reinforce the comment.
“At solar minimum, especially a ‘deep’ one as we now experiencing, the effect of active regions largely disappears and we observe a sort of solar ‘ground state’.”
Thank you for a well written post, Leif. This material is very interesting indeed. One has to wonder what the implications are if Livingston & Penn are correct. If so, are there any theories at all as to how long the effect will last?
Dr. Svalgard: thanks very much. Clear, methodical, modest (qualifications and cautions to help readers not infer too much). Makes the conclusion all the more impressive: something has changed. Probably the Sun but we don’t yet know. We do know that we can’t just blithely count Sunspots and assume they’re a “true” proxy for the 10.7 cm flux levels.
Great, great site.
Per Penn & Livingston the magnetic fields of sunspots have been decreasing while the temperature has been increasing that may indicate internal dynamic changes are occurring in the sun?
“Bill Marsh (06:55:24) :
I’m not sure if I would call the fact the Livingston & Penn may be correct ‘exciting’. I’m hoping they are not correct, I have no desire to enter a Maunder type minimum during my declining years. It’s bad enough that the Mayan/Olmec end of the next 52,000 years cycle is about a month after I’m supposed to retire, but thinking that my retirement may end up being in a new ‘little ice age’ is not pleasant.”
Wouldn’t you rather experience retirement in an exciting era!? Who knows what will happen? Mauder or not these are exciting times… It is an interesting coincidence that the Mayans predicted the ‘death of the 4th sun’ around this time…
Speaking of sun, it appears that a possible cycle 23 region is slowly drifting across the behind images, and should reach earthside soon… perhaps 23 wants to generate one last dazzling display for all those cycle 23 haters 🙂
Thanks to Lief for such a good work. Thanks David Hagen for the link to Scafetta´s PP. It is time to revisit Jose, Shirley, Fairbridge, and others.
Well Dr. Svalgard, I can’t say that I have much of a clue as to what that is all about; but it sure does look like very nice data of whatever is being depicted; and as you say, it does seem to give some good input to what goes on on the sun, that we don’t often hear about.
So you have sent me scramblng to read your text in detail, and try to digest it, and dig into some background of this kind of phenomenon.
It is nice to see data, with good agreement between different groups of researchers.
Thank you for taking the time to present this for us; and in such a readable way too. Now If I can figure out how to get my computer to make me a decent copy of this report, I can find a quiet corner to try and digest it.
As you point out, the constancy of the lows is very impressive. How nice it is to have such a long record of what looks like clean data without a lot of hiccups/accidents/mistakes, and the like that sometimes seem to spoil otherwise good data sets.
One question: the cyclic curves such as your figure 1 show a lot of “fur” on the tops of the peaks, which seems to diminish with signal amplitude. Whenever I see such signals; I am always curious as to how much is “noise” and how much is real signal. So is the 27 day running average the “real” signal, and the fur just measurment or instrumental noise; or is the fur real data too ?
George
Bill Marsh (06:55:24)
I’m hoping they are not correct, I have no desire to enter a Maunder type minimum during my declining years
We are living in interesting times, at our declining years :-), read this:
” What we are seeing here may be akin to the resetting of a clock. Alternatively we could compare this to the ocasional “clunk” of a system of gears when one is missing a tooth, causing slippage at intervals. The hypothesis of a relationship linking the solar motion with the generation of solar activity implies that this event is likely to perturb magnetic field and/or the flows of materials within the sun perhaps in important ways”
James Shirley
http://www.giurfa.com/james_shirley.pdf
deadwood (22:55:18) :
One question: Do you think the change in slope of tail of cycle 23 have any connection to the apparent changes in the nature of sunspots? And if so, what would be your explanation.
The slope of what? F10.7 or SSN? In any event, the downslope seems pretty much the same in all cycles. It is the upslope that is different [big cycles rise fast].
Roger Carr (23:13:59) :
Would you, or your 11 years old grandson, tell me (relative to these words above “…that the sunspots are getting warmer…”) the temperature of a sunspot and the temperature of the surrounding solar surface?
Same Bill Livingston has shown that the surrounding surface has no change in temperature.
Pat (00:06:17) :
but surely also the Sun could be “cooler”, closely matching the temperature of the spot, too?
See answer above.
Rik Gheysens (00:18:28) :
So there seems be no basis for the vanishing of the sunspots in 2015 as worded by Livingston & Penn! Certainly there is a vanishing, but not linearly.
No linear trend should be taken too literally. SSN does not go negative. All L&P are really saying is that there might a lot fewer visible spots.
Disputin (00:27:19) :
the geomagnetic field has been losing strength for some time and there has been speculation that it is about to flip polarity again. Any possible connection?
Just about in 500 years… No connection as far as I can see.
ralph ellis (00:31:54) :
Well if Radio flux is proportional to Sunspots, then one would expect the baseline of all the Radio flux minima to be identical, would you not?
Yes, and that is what we observe, just check Figure 1, where I went to pains [green box] to point that out.
bill (01:41:05) :
If one of the dishes has a narrower beam that misses some of the suns disk
They measure the full-disk [Sun-as-a-star] radiation.
Walt Stone (03:24:01) :
Is it then complete speculation to suggest that during historical solar minima, some sunspots were not counted because the spots warmed up to the extent they couldn’t be seen?
It is, but a very reasonable speculation, and may very well be true [my money is on that it is].
—-
More to come.