Posts Tagged ‘Solar Cycle’
After being starved of any significant solar activity for so long, any detection of a sunspot very nearly becomes headline news. Therefore when a significant spot is detected on the solar farside, people start writing furiously.
So what to do? The first detection of a potential (and substantial) sunspot in more than a month came from GONG
But will it survive to the nearside?
There’s something that might be a spot on the far eastern limb of the latest STEREO image
But GONG now shows nothing at all
So what to believe? The next few days should show whether we’re looking at a spot or a plage. I confess that the sensitivity of the seismic results interpreted by GONG are often less accurate as to whether we are seeing a solar disturbance (like a coronal hole or a prominence) or a real sunspot.
I suspect that this is continuation of a pattern we have been seeing for many months, a single sunspot or very small group with SC24 polarity passes in front of us, but nothing else happens and the Sun’s activity quickly falls back to very low levels.
Because of this phenomenon, the most likely response from the solar science community is likely to be muted, after so many false dawns.
Solarcycle24.com has produced a graph showing the remarkable difference between the spotless days between solar cycles 22 and 23 and between 23 and 24.
There’s no end in sight for this minimum.
September 3, 2009: The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?
“Personally, I’m betting that sunspots are coming back,” says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, “there is some evidence that they won’t.”
Penn’s colleague Bill Livingston of the NSO has been measuring the magnetic fields of sunspots for the past 17 years, and he has found a remarkable trend. Sunspot magnetism is on the decline:
Above: Sunspot magnetic fields measured by Livingston and Penn from 1992 – Feb. 2009 using an infrared Zeeman splitting technique.
“Sunspot magnetic fields are dropping by about 50 gauss per year,” says Penn. “If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015.”
Hmmm, yes they could. But the solar magnetic field could simply be in a cyclical downturn of which this is a part. We need an expert!
“This work has caused a sensation in the field of solar physics,” comments NASA sunspot expert David Hathaway, who is not directly involved in the research. “It’s controversial stuff.”
The controversy is not about the data. “We know Livingston and Penn are excellent observers,” says Hathaway. “The trend that they have discovered appears to be real.” The part colleagues have trouble believing is the extrapolation. Hathaway notes that most of their data were taken after the maximum of Solar Cycle 23 (2000-2002) when sunspot activity naturally began to decline. “The drop in magnetic fields could be a normal aspect of the solar cycle and not a sign that sunspots are permanently vanishing.”
Yes, what he said.
Penn himself wonders about these points. “Our technique is relatively new and the data stretches back in time only 17 years. We could be observing a temporary downturn that will reverse itself.”
The technique they’re using was pioneered by Livingston at the NASA-supported McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun’s atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called “Zeeman splitting” after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism
If the solar magnetism continues to decline what could this mean for the Earth?
If sunspots do go away, it wouldn’t be the first time. In the 17th century, the sun plunged into a 70-year period of spotlessness known as the Maunder Minimum that still baffles scientists. The sunspot drought began in 1645 and lasted until 1715; during that time, some of the best astronomers in history (e.g., Cassini) monitored the sun and failed to count more than a few dozen sunspots per year, compared to the usual thousands.
Note that of course, they don’t mention that this coincided with the coldest part of the Little Ice Age. But that would be politically incorrect, wouldn’t it?
“Whether [the current downturn] is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen,” Livingston and Penn caution in a recent issue of EOS. “Other indications of solar activity suggest that sunspots must return in earnest within the next year.”
I’d love to know what those other indications are, because the prognostications of future solar activity have been startlingly poor from practically everybody.
I leave the last words to David Hathaway, who dares to speak the truth to solar science:
Whatever happens, notes Hathaway, “the sun is behaving in an interesting way and I believe we’re about to learn something new.”
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- Sunspots May Be Different During This Solar Minimum (science.slashdot.org)
- Is the Sun Missing Its Spots? (nytimes.com)
- “DEAD AS A DOORNAIL:” More on those missing sunspots. “Most solar physicists do not think anything… (pajamasmedia.com)
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.
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 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.
The SOHO instruments are offline while new software commands are uploaded. As the main instruments are offline, the other CCD systems are being baked out (heated up to clear dead pixels)
Solar and Heliospheric Observatory (SOHO) is having a minor problem. SOHO’s white light solar telescope is temporarily offline while new commands and data tables are uploaded to the spacecraft. Normal operations are expected to resume in a few days.
Hence no updates on the state of the Sun.
The Sun could have a sudden burst of activity and we’d never know.
The Sun has gone back to blank after having had just one sunspot group that caused otherwise rational people to go off their heads…
Here’s the magnetogram of the Sun showing precisely nothing that presages any sunspot formation:
As a comparison, here is the sun image from the Extreme ultraviolet Imaging Telescope at 304 ångstroms for today and near solar maximum in 2000 by way of comparison
Now its easy to see how quiet the Sun really is at the moment. The prominences are weak, the coronal holes are very small, the corona (the solar atmosphere) shrunken.
All of this can be seen to be normal behaviour for the Sun, except that this hiatus between Solar Cycle 23 finally winding down and the next cycle is unprecedented in nearly a hundred years. (By the way, the overuse of “unprecedented” by climate alarmists has me wincing at using it as a cliché)
Eventually the solar cycle must return. The question is whether solar scientists gain insight into the behaviour of the Sun by understanding why their models failed (see below). The result can only be better science.
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Previously on this blog, I’d mentioned my skepticism that one decent sunspot marked the end of the hiatus in the solar cycle we’ve seen for nearly two years. It might be my nature, but everybody has been wrong before.
As part of my public duty to actually ask real scientists monitoring the Sun, I wrote to Dr Ken Tapping of Canada’s National Research Council at the Herzberg Institute of Astrophysics in British Columbia:
Dear Dr Tapping
For the first time in a very long time, the Sun has managed to produce a sunspot (1024) which has lasted more than a few hours.
Is there any sign of an upswing in radio emissions indicating an end to the hiatus?
and Dr Tapping replied (with my emphasis):
Last weekend I saw a really nice sunspot group on the Sun, which could have been part of the new cycle. The solar radio flux went up a little while it was there. However now the flux has slumped back to low values again.
Some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it. I’m not sure what that really means, so I am making no suggestion as to what is going on.
Being very conservative, according to the measurements being made under our Solar Radio Monitoring Programme, we have yet to see signs the next cycle is really under way.
Now this is what I’d thought, that the nice sunspot (1024) we’d seen did not presage a change in the behavior of the Sun: the solar wind speed remained subdued, coronal holes remained very small, there were no prominences to speak of.
It also baffles me how “some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it”. If there are very few sunspots and the radio flux remains extremely subdued, on what basis are these theorists making their statements?
It could be that this is the first “radio quiet” solar cycle … anyone believe that?
So for solar physicists, it remains “interesting times” and probably a time to clear out some old theories and start again.
My thanks to Dr Tapping for the correspondence.