Solar Science

Looking back into the archives, there are many many predictions of the start and size of solar cycle 24 given on the highest possible scientific authority that turned out to be flat out wrong.

Here’s one

March 10, 2006: It’s official: Solar minimum has arrived. Sunspots have all but vanished. Solar flares are nonexistent. The sun is utterly quiet.

Like the quiet before a storm.

This week researchers announced that a storm is coming–the most intense solar maximum in fifty years. The prediction comes from a team led by Mausumi Dikpati of the National Center for Atmospheric Research (NCAR). “The next sunspot cycle will be 30% to 50% stronger than the previous one,” she says. If correct, the years ahead could produce a burst of solar activity second only to the historic Solar Max of 1958.

This is important. The solar minimum began around March 2006 and today August 30, 2009 the Sun is still in that minimum with no sign of it ending.

The failed predictor: The Solar Conveyor Belt Theory

Dikpati’s prediction is unprecedented. In nearly-two centuries since the 11-year sunspot cycle was discovered, scientists have struggled to predict the size of future maxima—and failed. Solar maxima can be intense, as in 1958, or barely detectable, as in 1805, obeying no obvious pattern.

The key to the mystery, Dikpati realized years ago, is a conveyor belt on the sun.

I try to remove some of the waffle here because the article talks about the Earth’s ocean conveyor belt as an analogue but frankly its not relevant, nor useful.

The sun’s conveyor belt is a current, not of water, but of electrically-conducting gas. It flows in a loop from the sun’s equator to the poles and back again. Just as the Great Ocean Conveyor Belt controls weather on Earth, this solar conveyor belt controls weather on the sun. Specifically, it controls the sunspot cycle.

Solar physicist David Hathaway of the National Space Science & Technology Center (NSSTC) explains: “First, remember what sunspots are–tangled knots of magnetism generated by the sun’s inner dynamo. A typical sunspot exists for just a few weeks. Then it decays, leaving behind a ‘corpse’ of weak magnetic fields.”

Enter the conveyor belt.

The Solar Conveyor belt according to NASA

“The top of the conveyor belt skims the surface of the sun, sweeping up the magnetic fields of old, dead sunspots. The ‘corpses’ are dragged down at the poles to a depth of 200,000 km where the sun’s magnetic dynamo can amplify them. Once the corpses (magnetic knots) are reincarnated (amplified), they become buoyant and float back to the surface.” Presto—new sunspots!

Presto! No, it didn’t this time. This time the belt moved to the critical latitude of 22 degrees and we got a single sunspot and that’s it.

All this happens with massive slowness. “It takes about 40 years for the belt to complete one loop,” says Hathaway. The speed varies “anywhere from a 50-year pace (slow) to a 30-year pace (fast).”

When the belt is turning “fast,” it means that lots of magnetic fields are being swept up, and that a future sunspot cycle is going to be intense. This is a basis for forecasting: “The belt was turning fast in 1986-1996,” says Hathaway. “Old magnetic fields swept up then should re-appear as big sunspots in 2010-2011.”

There’s the prediction from 2006. We’ve yet to reach 2010 but Hathaway was talking about 2010-2011 as the time of the SC24 maximum when we haven’t yet reached the end of the minimum in August 2009.

Here’s where the claim of scientific authority is made. This isn’t just any old joe making a prediction, this is expertise:

Like most experts in the field, Hathaway has confidence in the conveyor belt model and agrees with Dikpati that the next solar maximum should be a doozy. But he disagrees with one point. Dikpati’s forecast puts Solar Max at 2012. Hathaway believes it will arrive sooner, in 2010 or 2011.

“History shows that big sunspot cycles ‘ramp up’ faster than small ones,” he says. “I expect to see the first sunspots of the next cycle appear in late 2006 or 2007—and Solar Max to be underway by 2010 or 2011.”

Wrong. An expert strikes out.

Who’s right? Time will tell. Either way, a storm is coming.

It turns out that neither was right. The extended solar minimum caught some of NASA’s brightest experts with their predictive pants down.

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.

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

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 

This one could be filed under “Solar Cycle 24 pessimism”

Lawrence Solomon in the Financial Post (Canada) writes:

You probably haven’t heard much of Solar Cycle 24, the current cycle that our sun has entered, and I hope you don’t. If Solar Cycle 24 becomes a household term, your lifestyle could be taking a dramatic turn for the worse. That of your children and their children could fare worse still, say some scientists, because Solar Cycle 24 could mark a time of profound long-term change in the climate. As put by geophysicist Philip Chapman, a former NASA astronaut-scientist [pictured above] and former president of the National Space Society, “It is time to put aside the global warming dogma, at least to begin contingency planning about what to do if we are moving into another little ice age.”

The sun, of late, is remarkably free of eruptions: It has lost its spots. By this point in the solar cycle, sunspots would ordinarily have been present in goodly numbers. Today’s spotlessness — what alarms Dr. Chapman and others — may be an anomaly of some kind, and the sun may soon revert to form. But if it doesn’t – and with each passing day, the speculation in the scientific community grows that it will not – we could be entering a new epoch that few would welcome.

It’s interesting that not everybody has swallowed the idea that cooling down the Earth is Good Idea.

The Little Ice Age was no fun at all

The consequences of the Little Ice Age, because they occurred in relatively recent times, have come down to us through literature and the arts as well as from historians and scientists, government and business records. When Shakespeare wrote of “lawn as white as driven snow,” he had first-hand experience – Europe was bitterly cold in his day, a sharp contrast to the very warm weather that preceded his birth. During the Little Ice Age, the River Thames froze over, the Dutch developed the ice skate and the great artists of the day learned to love a new genre: the winter landscape.
In what had been a warm Europe , adaptations were not all happy: Growing seasons in England and Continental Europe generally became short and unreliable, which led to shortages and famine. These hardships were nothing compared to the more northerly countries: Glaciers advanced rapidly in Greenland, Iceland, Scandinavia and North America, making vast tracts of land uninhabitable. The Arctic pack ice extended so far south that several reports describe Eskimos landing their kayaks in Scotland. Finland’s population fell by one-third, Iceland’s by half, the Viking colonies in Greenland were abandoned altogether, as were many Inuit communities. The cold in North America spread so far south that, in the winter of 1780, New York Harbor froze, enabling people to walk from Manhattan to Staten Island.

Actually the Viking colonies were not abandoned. The colonists were marooned on Greenland because a) the Viking boats could no longer get to them because of advancing glaciers and sea ice and b) they had no wood to spare to make boats.

So they dwindled and eventually starved to death.

By complete coincidence this coincided with a solar minimum lasting around 70 years.

In early January 2008, NASA reported the start of Solar Cycle 24 with the sighting of a tiny reversed polarity spot. It lasted three days and then disappeared.

This was reported by Anthony Watts thus:

Solar physicists have been waiting for the appearance of a reversed-polarity sunspot to signal the start of the next solar cycle. The signal for the start of a new cycle is sighting a particular kind of sunspot. That wait is over.

And the NASA blog said:

“On January 4, 2008, a reversed-polarity sunspot appeared—and this signals the start of Solar Cycle 24,” says David Hathaway of the Marshall Space Flight Center.

Above: Images of the first sunspot of Solar Cycle 24 taken by the NASA/ESA Solar and Heliospheric Observatory (SOHO).

Solar activity waxes and wanes in 11-year cycles. Lately, we’ve been experiencing the low ebb, “very few flares, sunspots, or activity of any kind,” says Hathaway. “Solar minimum is upon us.”

But the first announcement of Solar Cycle 24 wasn’t made by NASA in January 2008 – it was actually made by Ulrich Reith on 31 July 2006, with this post:

Last night it seems to have happend, the first sunspot of solar cycle 24 appeard on the southern hemisphere of the sun.
Very close to NOAA 10902 a tiny spot which should be named 10903 appeared at S12W55.
In the SOHO MDI magnetogramms it clearly shows a reversed polarity if compared to the polarity of cycle 23. (cycle 23: black first towards the western limb and white following black / cycle 24: white in front of black)

And I show the picture with an arrow so you know which spot we’re talking about.

Again, the spot persisted for a few days and disappeared.

So what to believe? The transition between one solar cycle and the next is very difficult to call as during the transition both magnetically polarized spots can be seen. The newer cycle spots are usually high latitude (>20^o) North and South of the solar equator. Solar cycle 23 spots still continue to produce and any SC24 spots so far are barely a pixel in size and very rare.

Solar cycle 24 remains difficult to call definitively at this time, in my view.

Much excitement from NASA, as the long delayed arrival of Solar Cycle 24 was announced:

Dec. 14, 2007: The solar physics community is abuzz this week. No, there haven’t been any great eruptions or solar storms. The source of the excitement is a modest knot of magnetism that popped over the sun’s eastern limb on Dec. 11th, pictured below in a pair of images from the orbiting Solar and Heliospheric Observatory (SOHO).

It may not look like much, but “this patch of magnetism could be a sign of the next solar cycle,” says solar physicist David Hathaway of the Marshall Space Flight Center.

Yeees, go on…

“New solar cycles always begin with a high-latitude, reversed polarity sunspot,” explains Hathaway. “Reversed polarity ” means a sunspot with opposite magnetic polarity compared to sunspots from the previous solar cycle. “High-latitude” refers to the sun’s grid of latitude and longitude. Old cycle spots congregate near the sun’s equator. New cycle spots appear higher, around 25 or 30 degrees latitude.

OK, got that. Now we have a sunspot with reversed polarity compared to solar cycle 23?

The region that appeared on Dec. 11th fits both these criteria. It is high latitude (24 degrees N) and magnetically reversed. Just one problem: There is no sunspot. So far the region is just a bright knot of magnetic fields. If, however, these fields coalesce into a dark sunspot, scientists are ready to announce that Solar Cycle 24 has officially begun.

And did this coalesce into a sunspot? No. The Sun remains stubbornly blank although there was a fair sized SC23 spot for several days that followed.There appears to be indications of a large sunspot on the far side of the Sun but that too is right on the equator and probably isn’t polarity reversed from SC23.

This isn’t the first time that a sunspot appeared to herald the next solar cycle that failed to materialize. There was another which appeared in late 2006 that got people excited for literally hours when it appeared and disappeared.

Hathaway, it must be remembered, was one of a team who predicted a very strong SC24, at least as strong as the previous one. I think the tension may be getting to him.

I think its OK to actually wait for at least a couple of magnetically reversed sunspots to appear at high latitudes before announcing the Coming of the next Solar Cycle. Whatever happens, SC24 will be late.

From NASA website:

Solar cycle 24, due to peak in 2010 or 2011 “looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago,” says solar physicist David Hathaway of the Marshall Space Flight Center. He and colleague Robert Wilson presented this conclusion last week at the American Geophysical Union meeting in San Francisco.

Their forecast is based on historical records of geomagnetic storms.

Hathaway explains: “When a gust of solar wind hits Earth’s magnetic field, the impact causes the magnetic field to shake. If it shakes hard enough, we call it a geomagnetic storm.” In the extreme, these storms cause power outages and make compass needles swing in the wrong direction. Auroras are a beautiful side-effect.

Hathaway and Wilson looked at records of geomagnetic activity stretching back almost 150 years and noticed something useful:. “The amount of geomagnetic activity now tells us what the solar cycle is going to be like 6 to 8 years in the future,” says Hathaway. A picture is worth a thousand words:

Hathaway's comparison of solar and geomagnetic fields

Above: Peaks in geomagnetic activity (red) foretell solar maxima (black) more than six years in advance. [More]

In the plot, above, black curves are solar cycles; the amplitude is the sunspot number. Red curves are geomagnetic indices, specifically the Inter-hour Variability Index or IHV. “These indices are derived from magnetometer data recorded at two points on opposite sides of Earth: one in England and another in Australia. IHV data have been taken every day since 1868,” says Hathaway.

Cross correlating sunspot number vs. IHV, they found that the IHV predicts the amplitude of the solar cycle 6-plus years in advance with a 94% correlation coefficient.

“We don’t know why this works,” says Hathaway. The underlying physics is a mystery. “But it does work.”

And here’s the prediction for Solar Cycle 24 based on this “mystery”:

Hathaway's 2006 prediction of SC24

Never mind that this thing looks a lot like numerology – if its from NASA and has a nice graph it must be worth something