Hot off the press.

NASA announces yet another explanation for the late arrival of Solar Cycle 24 (nearly two years after it was supposed to have started).

June 17, 2009: The sun is in the pits of a century-class solar minimum, and sunspots have been puzzlingly scarce for more than two years. Now, for the first time, solar physicists might understand why.

At an American Astronomical Society press conference today in Boulder, Colorado, researchers announced that a jet stream deep inside the sun is migrating slower than usual through the star’s interior, giving rise to the current lack of sunspots.

Rachel Howe and Frank Hill of the National Solar Observatory (NSO) in Tucson, Arizona, used a technique called helioseismology to detect and track the jet stream down to depths of 7,000 km below the surface of the sun. The sun generates new jet streams near its poles every 11 years, they explained to a room full of reporters and fellow scientists. The streams migrate slowly from the poles to the equator and when a jet stream reaches the critical latitude of 22 degrees, new-cycle sunspots begin to appear.

Original Caption:
Above: A helioseismic map of the solar interior. Tilted red-yellow bands trace solar jet streams. Black contours denote sunspot activity. When the jet streams reach a critical latitude around 22 degrees, sunspot activity intensifies.

Howe and Hill found that the stream associated with the next solar cycle has moved sluggishly, taking three years to cover a 10 degree range in latitude compared to only two years for the previous solar cycle.

The jet stream is now, finally, reaching the critical latitude, heralding a return of solar activity in the months and years ahead.

“It is exciting to see”, says Hill, “that just as this sluggish stream reaches the usual active latitude of 22 degrees, a year late, we finally begin to see new groups of sunspots emerging.”

The current solar minimum has been so long and deep, it prompted some scientists to speculate that the sun might enter a long period with no sunspot activity at all, akin to the Maunder Minimum of the 17th century. This new result dispells those concerns. The sun’s internal magnetic dynamo is still operating, and the sunspot cycle is not “broken.”

So we should be seeing SC24 sunspots appearing now that the jet stream has reached the critical latitude of 22° ?

Let’s check out of the window:

The spotless disk of the Sun

Magnetogram shows little magnetic behaviour

OK, maybe it was just an off day on the Sun. What about the trend?

So far, indistinguishable from zero.

Here’s the 3D view of what the solar scientists are tracking/modelling (click to see the movie):

This movie reveals motions of the Sun’s interior as measured with helioseismology on data from GONG and SOHO/MDI. East to west motion is color coded: blue is slow, red is fast. A red band in the outer third of the Sun moves slowly down from near each pole toward the equator; that band is the jet stream that is associated with sunpot emergence and the solar cycle. As of early 2009 the Cycle 24 jet streams have just reached N/S 22 degrees latitude, and new sunspots are beginning to emerge.

Now I hate to be a killjoy, but all of this effort has failed to convince me that a deep down “jetstream” of charged plasma reaching a “critical” latitude can explain why the Sun remains so very quiet.

On SolarCycle24.com, they’ve got yet another sun speck recorded yesterday, that by today had disappeared. Exactly the same behaviour we’ve been having for 12 months with no end in sight.

Solar Cycle 24 spot - the start of something?

At least, it could be SC24 but the last magnetogram is from nearly 3 days ago.

I think the true test is if this spot lasts more than 48 hours. The others haven’t lasted that long.

This blog has quiet periods just like the Sun

I’ve just been in e-mail correspondance with Dr Kenneth Tapping, asking him to comment on the progress of the solar minimum and his opinion on the likely size of SC24 when it does deign to appear.

Dear Dr Tapping

After you published your rebuke to Investor’s Business Daily, I put your entire reply onto my blog (see http://solarscience.auditblogs.com/2008/04/22/ken-tapping-the-current-solar-minimum/ ) which I notice is the second listing when anyone googles your name. I hope you didn’t mind.

Since that reply the Sun has appeared to have gone into an even deeper slumber than it was when you wrote your article, more than a year ago. You ended that article with a statement

AT THE MOMENT IT IS UNJUSTIFIED TO ASSUME THE SUN IS UNDERGOING A SIGNIFICANT CHANGE IN BEHAVIOUR. ON THE BASIS OF SUNSPOT NUMBER DATA, WE CANNOT ASSUME ANYTHING ODD IS HAPPENING UNLESS THE NEXT CYCLE DELAYS ITS START INTO 2009 OR 2010

Well it’s now nearly mid-2009 and the only spots to be seen very very occasionally are SC23 polarity.

Do you have any further comment on the Sun’s (lack of) activity? Are we close to unusual times in solar activity? Is the sun undergoing a significant change in behaviour?

Best regards

John

He replied [with my emphasis]

Hi John,

I’ve just got back here from the Space Weather Workshop, which was held in Boulder, Colorado. The opinion there is that the next cycle is coming, although forecasts are for a low cycle with a late start.

Our radio telescopes have detected no sign of the new cycle yet. However a statistical study of indices that I have been doing suggests the Sun did show a significant change in behaviour over the last few years, but that things are starting to slip back towards the normal situation, which could suggest the Sun is at least showing signs of waking up again. It’s deciding to take an additional lie-in cannot be ruled out.

Activity is certainly very low.

Regards,

Ken

When I asked for that “statistical study of indices”, Dr Tapping replied that it was being submitted to a journal and he’d let me know when its in pre-print – which is fine by me.

I think it’s fair to say that all solar scientists have been caught out by the length of the solar minimum and the delay to SC24. In subsequent posts I’ll be reviewing the prognostications of solar models, in an effort to understand what exactly goes into predictions of solar cycles.

In other news, as reported on Watts Up With That:

NOAA/SWPC will be releasing an update to the Solar Cycle 24 Prediction on Friday, May 8, 2009 at noon Eastern Daylight Time (1600 UT) at a joint ESA/NASA/NOAA press conference

I can hardly wait.

NASA’s David Hathaway has announced, again, that Solar Cycle 24 may have begun:

After more than two years of very low sunspot activity and hardly any flares, the sun is ramping up activity now.

The sun’s activity ebbs and flows on a roughly 11-year cycle. It can range from very quiet to violent space storms that knock out power grids on Earth and disrupt radio and satellite communications. The last peak was in 2000, and scientists have in recent months figured the low point was occurring. Fresh sunspots during October suggest the corner has been turned.

“I think solar minimum is behind us,” said David Hathaway of NASA’s Marshall Space Flight Center in Huntsville, Ala. “Last month we counted five sunspot groups.” he says.

Sunspots are cool areas on the solar surface where magnetic energy is bottled up. While five groups is not extraordinary, it is significant in comparison to the months of virtually no spots.

“This represents a real increase in solar activity,” Hathaway said in a statement today.

Your tax money at work. At least he won’t have to keep stretching out the start of SC24 every few months.

Tags: Hathaway, NASA, solar cycle 24

Not a speck. Not a low latitude could-be-a-SC23 spot.

The real deal.

Sun on 13-10-2008 showing SC24 spot

The polarity is definitely reversed from the previous cycle. Its a high latitude spot. The companion spot is reverse polarity to the main spot.

Looks good to me.

The STEREO image (allows us to look around the limb of the Sun and see what’s coming) suggest an even larger area of activity at about the same latitude.

Stereo Image 12-10-2008

Now we wait to see if the SC24 persists.

The magnetogram shows the SC24 polarity:

Magnetogram from 13-10-2008 showing SC24 polarity

The solar magnetic field for September has just been published (as graphed by Anthony Watts) and shows the magnetic field to be at a historically low level, as NASA had already noted.

This may just prove to be the bottom of the Solar Cycle (yes, I’m sticking my neck out). Now we wait to see what happens next, because I’m not convinced that anyone really has a clue.

A quick update on David Hathaway’s predictions for Solar Cycle 24.

Dr Hathaway has changed his prediction once again WITHOUT changing the page that it occurs on (other than the date it was updated), nor with any explanation as to why his previous predictions have been so wrong. It would be nice if he would treat us all to an explanation for modifying his prediction without modifying his methodology.

Here is an animation done by Michael Romayne on how Hathaway’s prediction has changed over time.

Its clear that something so flexible as Hathaway’s predictions cannot have a theory behind them – this is just making ad hoc adjustments. Note also that between March 2007 and March 2008, the expected size of SC24 was reduced – why?

h/t to Anthony Watts 

I’ve noticed that David Hathaway is not backing down from his previous predictions that SC24 will be a) larger than SC23 and b) the length of SC24 will be approximately the same as previous cycles.

Here is the update:

Predicting the behavior of a sunspot cycle is fairly reliable once the cycle is well underway (about 3 years after the minimum in sunspot number occurs [see Hathaway, Wilson, and Reichmann Solar Physics; 151, 177 (1994)]). Prior to that time the predictions are less reliable but nonetheless equally as important. Planning for satellite orbits and space missions often require knowledge of solar activity levels years in advance.

A number of techniques are used to predict the amplitude of a cycle during the time near and before sunspot minimum. Relationships have been found between the size of the next cycle maximum and the length of the previous cycle, the level of activity at sunspot minimum, and the size of the previous cycle.

Among the most reliable techniques are those that use the measurements of changes in the Earth’s magnetic field at, and before, sunspot minimum. These changes in the Earth’s magnetic field are known to be caused by solar storms but the precise connections between them and future solar activity levels is still uncertain.

Of these “geomagnetic precursor” techniques three stand out. The earliest is from Ohl and Ohl [Solar-Terrestrial Predictions Proceedings, Vol. II. 258 (1979)] They found that the value of the geomagnetic a index at its minimum was related to the sunspot number during the ensuing maximum. The primary disadvantage of this technique is that the minimum in the geomagnetic aa index often occurs slightly after sunspot minimum so the prediction isn’t available until the sunspot cycle has started.

An alternative method is due to Joan Feynman. She separates the geomagnetic aa index into two components: one in phase with and proportional to the sunspot number, the other component is then the remaining signal. She found that this remaining signal faithfully represents the sunspot numbers several years in advance. The maximum in this signal occurs at sunspot minimum and is proportional to the sunspot number during the following maximum. This method does allow for a prediction of the next sunspot maximum at the time of sunspot minimum.

A third method is due to Richard Thompson [Solar Physics 148, 383 (1993)]. He found a relationship between the number of days during a sunspot cycle in which the geomagnetic field was “disturbed” and the amplitude of the next sunspot maximum. His method has the advantage of giving a prediction for the size of the next sunspot maximum well before sunspot minimum.

We have employed these methods along with several others to determine the size of the next sunspot cycle using a technique that weights the different predictions by their reliability. [See Hathaway, Wilson, and Reichmann J. Geophys. Res. 104, 22,375 (1999)] This analysis indicated (by mid-1996) a maximum sunspot number of about 154 ± 21. We then use the shape of the sunspot cycle as described by Hathaway, Wilson, and Reichmann [Solar Physics 151, 177 (1994)] and determine a starting time for the cycle by fitting the data to produce a prediction of the monthly sunspot numbers through the next cycle. We find a starting time of July 1996 with minimum occuring in October 1996. The predicted numbers are available in a text file, as a GIF image, and as a Postscript file. As the cycle progresses, the prediction process switches over to giving more weight to the fitting of the monthly values to the cycle shape function. At this phase of cycle 23 we now give full weight to the curve-fitting technique of Hathaway, Wilson, and Reichmann Solar Physics 151, 177 (1994). The two parameters for this fit (cycle amplitude and cycle starting time) have remained unchanged since early 1999.

Note: These predictions are for “smoothed” International Sunspot Numbers. The smoothing is usually over time periods of about a year or more so both the daily and the monthly values for the International Sunspot Number should fluctuate about our predicted numbers. Also note that the “Boulder” numbers reported daily at www.spaceweather.com are typically about 35% higher than the International sunspot number.

Another indicator of the level of solar activity is the flux of radio emission from the Sun at a wavelength of 10.7 cm (2.8 GHz frequency). This flux has been measured daily since 1947. It is an important indicator of solar activity because it tends to follow the changes in the solar ultraviolet that influence the Earth’s upper atmosphere and ionosphere. Many models of the upper atmosphere use the 10.7 cm flux (F10.7) as input to determine atmospheric densities and satellite drag. F10.7 has been shown to follow the sunspot number quite closely and similar prediction techniques can be used. Our predictions for F10.7 are available in a text file, as a GIF image, and as a Postscript file. Current values for F10.7 can be found at:
http://www.drao.nrc.ca/icarus/www/sol_home.shtml

Now the reason why I quote the entire blog post in full is because, for some reason, Dr Hathaway won’t blog in sequential format the way normal people do, instead preferring to re-edit his previous posts.

Editing history is Orwellian, Dr Hathaway

I received this via e-mail from K7RA. The original document comes from Dr Kenneth Tapping who was quoted not long ago regarding the solar cycle being “the quietest [he'd] ever seen in 25 years”. This was taken to mean that the current solar minimum was historically unusual, and here Dr Tapping explains that this is not so.

I reproduce here the entire document (other than stylistic changes from PDF to the blog, not a word or a graph has been altered from the original):

The Current Solar Minimum

Ken Tapping, 2008-04-17

This note summarizes my current feeling about the state of solar activity and the solar activity cycle. Any conclusions currently in circulation that have been drawn by extrapolating what you see in this note should not be regarded as reflecting my views. My conclusions are in this note. The information used here is freely available and readers are strongly encouraged to get the data, look at it and draw their own conclusions.

The current solar activity is not that unusual. At this point it is completely unjustified to see current solar behaviour as an indication of any departure from its what the Sun has been doing for at least the last 300 years.

Figure 1 shows a plot of solar activity as measured by the solar radio flux monitors operated by the National Research Council of Canada.

Figure 1: Monthly averaged 10.7 cm solar radio flux solar activity index since 1947 (monthly means).

The arrow under the 1964-1977 cycle indicates the length of that cycle, which was a little longer than the others. That same arrow has been copied and put under the last cycle. The length is unchanged. It can be seen that the current solar activity cycle (now ending) has not yet exceeded the length of the 1964-77 cycle. It is also clear that the longish cycle in 1964-77 was followed by further activity cycles – normal solar behaviour. To exceed the duration of the 1964-1977 cycle, the new cycle would have to delay its start at least well into 2009.

Figure 2 shows the 1964-77 and the 1997-? cycles overlaid on the same plot. Once again we can see the last cycle has yet to last longer than the 1964-77 cycle.

Figure 2: The 1964-77 cycles compared. The current cycle (black trace) has yet to last longer than the 1964-77 cycle (red trace).

The 10.7 cm solar flux covers only about six solar activity cycles. Sunspot number data covers at least 300 years. The histogram Figure 3 shows how the durations of the cycles as seen in the sunspot data have varied since 1700. A 13-year activity cycle is not that unusual.

Figure 3: Distribution of solar cycle durations over the last 300 years. The 1964-1977 cycle, having a
duration of 13 years is unusual, but not that unusual.

CONCLUSION: AT THE MOMENT IT IS UNJUSTIFIED TO ASSUME THE SUN IS UNDERGOING A SIGNIFICANT CHANGE IN BEHAVIOUR. ON THE BASIS OF SUNSPOT NUMBER DATA, WE CANNOT ASSUME ANYTHING ODD IS HAPPENING UNLESS THE NEXT CYCLE DELAYS ITS START INTO 2009 OR 2010.

Another week of excitement as the second solar cycle 24 spot appeared…and then disappeared just as rapidly.

I can’t help feeling that with an unprecedented amount of high technology monitoring the Sun with ever higher resolution, the criteria by which a sunspot is defined has become radically weakened to such an extent that it all becomes meaningless.

On Climate Audit commenters noted that the criteria for naming hurricanes had become so weakened that practically any frontal wave in the Eastern Atlantic that persisted for more than a few hours got a name (the so-called “Tiny Tims” of the hurricane season).

So it appears to be with sunspots and Solar Cycle 24. Here is that second solar cycle 24 sunspot numbered for all to see:

Now in order to ascertain that there really is a spot there, I had to first make sure my laptop screen was really clean because it could have been hidden behind a rogue speck of dust and I could have missed it.

Can you spot it? If so, you’re better than I.

Here’s three views looking at the same spot. It may be there in the magnetogram showing the class signs of magnetic polarity reversal and there may be an associated phage (often the precursor of a sunspot) but is there a sunspot?

Meanwhile a few days later, yet another SC23 spot comes into view.

I can’t help but feel that this is all a little desperate. SC24 continues to surprise with its general unwillingness to make an unambiguous appearance.

An interesting overview on the two competing theories within NASA on Solar Cycle 24 from amateur solar watcher Tad Cook, also known under his radio ham designation K7RA:

A new forecast is out regarding progress between Solar Cycles 23 and 24. You may recall that the committee of scientists who make a group forecast of future sunspot activity for the NOAA Space Weather Prediction Center were unable to reach a consensus last year, the group evenly split between those who think the next solar cycle will be weak and those that see a stronger solar cycle.

I will refer to the weak cycle predictors as pessimists and strong cycle forecasters as optimists. While these characterizations may not be appropriate for scientists who presumably have no preference either way, as far as Amateur Radio operators are concerned, the high cycle prediction is no doubt the optimistic choice.

The previous prediction appeared in the January 2, 2008, issue 1687 of the Preliminary Report and Forecast. Note on page 8 in the table of predicted smoothed sunspot numbers that the optimistic faction predicts a sunspot minimum of 4 centered around December 2007-April 2008. The pessimistic projection is for a smoothed sunspot number minimum of 3 from January-April 2008.

Now compare this with the prediction ten weeks later on page 9 of issue 1697 from this week. See how the pessimists are now calling for a much longer and lower solar minimum lasting over a year, from November 2007-December 2008. But according to the optimists, the solar minimum has already passed, with a smoothed sunspot number of 6 in August and September 2007 (this generally agrees with our 3-month averages of daily numbers, presented in last week’s bulletin.)

Note there is no split in the value for August 2007. This is because 6 is the known smoothed sunspot number for that month, not a prediction. A year of daily sunspot numbers is required to calculate the smoothed value, and all of the values from mid-February 2007 through mid-February 2008 (a whole year with August in the middle) are known. In fact, enough sunspot data will be known this weekend to fix the smoothed sunspot number for September of last year.

Now look at even better news for sunspot fans. See how the predictions for the peak of the next solar cycle have shifted and both factions see Cycle 24 peaking much higher than they did 10 weeks earlier.

In issue 1687, pessimists predicted a peak between May and October 2012 of only 90, but now in issue 1697, we see a much higher and earlier peak at 124 from August-December 2011, only three and a half years from now. The optimists and pessimists now agree on the timing of the peak, and optimists have upped their peak value prediction from 140 to 154 (access all recent weekly issues here.)

Of course, with only 23 cycles of data to examine, sunspot cycle prediction is still a young science. But new tools unavailable in past decades no doubt have advanced the art.