The 23rd Cycle’s Last Gasp?
Published on Mar 28, 2008 at 12:05 pm.
10 Comments.
Filed under Sun.
The Sun goes through a cycle of sunspot activity that lasts about 11 years. It isn’t an exact period, sometimes it is a little short, say 10 years, and sometimes a little long, as in 12 years. These sunspot cycles have been studied continuously for nearly 250 years. The Sun just started the 24th cycle since we’ve been keeping close watch. But, the 23rd cycle isn’t quite over yet, as evidenced by this past week’s sunspot activity.
Typically, sunspots begin forming in a cycle, then more and more of them form, until the Sun almost always has many sunspots on its surface every time that you look at it. Then, the number of sunspots diminish until sunspots are occasional features. At this minimum of activity, the Sun often has no sunspots visible when you look at it. The Sun is currently near a sunspot minimum. So, you don’t normally expect to see sunspots. If you do, there is normally just one or two sunspots. Right now, there are three large groups of sunspots. And, by large groups, I mean that the sunspots themselves are on on the order of the size of Earth, and the group may be nearly the size of the planet Jupiter, as seen in the diagram below.
It is not common to have so many large sunspots groups at solar minimum, but it is by no means unprecedented. We simply would not expect this situation to continue for very long. These spots will go away, and the Sun will once again be quite for a while. Eventually, in just a few years, though, the images that you see here will look like a typical day on the Sun (except for the location of the sunspots).
The 23rd cycle peaked in 2000, and the number of sunspots began to ebb. However, activity picked up and there was a second peak in about 2002. A double peaked sunspot cycle is unusual, but it also not without precedent. This past year was solar minimum. In January 4, the first sunspots of the new 24th cycle were seen. But, these sunspots are part of the 23rd cycle. So, you might be wondering how I can say these sunspots are part of the 23rd cycle. After all, if the 24th cycle has already started, wouldn’t these be sunspots associated with that cycle?
Well, it isn’t that simple. As it turns out, sunspots are associated with solar magnetic activity. For reasons that are a bit more complicated than I want to get into for this posting, the Sun’s magnetic field tends to bunch up and intensify. Where this happens, the magnetic bundles tend to move to the surface of the Sun and arch through the surface. The normal convection in the Sun (hot gas rising, cool gas sinking) is retarded in these regions of intense magnetic field. So, the gas cools slightly but does not sink. That makes these regions of the Sun a bit less blindingly bright, so they appear dark in comparison to the rest of the Sun. That is where sunspot comes from. The solar activity models describing this scenario are based on the work of Horace W. Babcock and Robert B. Leighton.
One of the key things about the Babcock-Leighton models is that they reproduce something that astronomers have observed for many decades: the Sun appears to reverse its magnetic field every solar cycle. That means that there is about a 22 year magnetic solar cycle. The sunspots that form have a distinctive magnetic polarity. The leading sunspot (p-spot) of a group tends to have magnetic polarity the same as whatever hemisphere of the Sun the sunspot group is in. So, if the northern hemisphere is magnetically a south magnetic pole, then so is the leading sunspot of a group. The trailing sunspot (f-spot) is typically of opposite polarity. Naturally, it can get more complicated than this, of course, but this is the simple version of sunspots. Since the Sun flips its magnetic polarity with each sunspot cycle, then so do the leading and trailing sunspots. Thus, you can tell whether the sunspots are part of the old cycle or the new cycle by observing their magnetic polarity. These sunspots have polarities consistent with the 23rd cycle, not the new 24th cycle. Below is a magnetogram showing magnetic field polarities on the surface of the Sun.
But, as I said before, there has already been a sunspot group with polarity of the new cycle, so what gives? Isn’t it strange to have sunspots from the old cycle still forming when there is a new cycle starting? Well, no, that isn’t at all unusual. In fact, it is pretty normal.
A little over a century ago, the British astronomer Edward Maunder observed that Sunspots don’t appear just randomly on the surface of the Sun. Rather, early in a solar cycle, the sunspots tend to appear at high latitudes. Then, as the sunspot cycle progresses, the sunspots tend to appear at lower and lower latitudes. Eventually, just as the sunspot cycle is ending, the last sunspots of the cycle appear near the equator. Plotting this over time gives a graphic as seen below. Since the sunspot pattern resembles a flock of butterflies flying in a line, this is often called a Maunder butterfly diagram.
One cycle ends at about the time that the next one starts, but if you look carefully at the diagram, you’ll notice that there are some times when there are sunspots from the old cycle near the equator and sunspots from the new cycle at high latitudes. So, it is perfectly natural for there to be an overlap of the sunspot cycles near solar minimum. However, don’t expect a lot more sunspots from the old cycle. It is very near its end, and this may be the last major sunspot event associated with the 23rd cycle. Interestingly, though, the magnetic activity associated with these sunspot groups has resulting in solar flares that have hurled charged particles across the Solar System towards Earth. The impact of these particles with Earth’s magnetosphere resulting in disturbances to Earth’s magnetic field that we call a geomagnetic storm. These storms are not considered a hazard to human life, but they can affect many of the things that we take for granted in a technological society. So, disturbances to Earth’s magnetic field are monitored. There is even a rating scale for the severity of geomagnetic storms. I’ll be writing more about these events in the coming years as solar activity increases and the likelihood of geomagnetic storm activity increases.
-Astroprof
Solar Images courtesy SOHO
Butterfly diagram courtesy of NASA MSFC
Dalton Minimum Watcher on March 29, 2008 at 12:50 pm: 1
Well-done article!
I am curious, however. I found you by way of a google alert which watches for the words ‘Maunder’ and ‘Dalton’ minimums. You mention Maunder, but not the main item which has come away with his name- the Maunder Minimum, which is a period of much colder climate which is associated with the solar cycles.
It is believed that we are currently heading for a Dalton Minimum with Cycle 24, and I look forward to reading explanations on this coming period of climate change it will be causing.
Astroprof on March 29, 2008 at 2:42 pm: 2
Maunder is actually known for a variety of things in the field. The Maunder minimum, which nearly coincided with the Little Ice age is only one of those things.
There is some indication that there is a several hundred year solar cycle of minima, of which the Maunder minimum is just one example. If so, they we may be coming up to one this century. However, early indications (which could be wrong) are that the 24th Cycle may be a fairly active one, suggesting that the next minimum may be a way off, yet. The next few years should tell.
Tad Cook on March 29, 2008 at 3:35 pm: 3
I want to comment on the comment about Maunder, Dalton and colder climate.
I’ve seen no scientific evidence, nor any consensus among scientists that “we are currently heading for a Dalton Minimum”, but let me tell you where I believe this idea is resonating.
It is fast becoming a matter of faith among so-called “global warming skeptics”, many of whom believe that the growing scientific evidence for carbon-influenced climate change is just part of some plot by left-wing scientists who “hate America”, love taxes, and want to bring American society to its knees. If you haven’t run into this concept, check the right-wing blogosphere or listen to Rush Limbaugh.
For some reason, they have become absolutely certain that the activity of a human population now reaching 6.7 billion people cannot affect climate, AND that there is an absolutely certain and provable link between high sunspot activity and global warming.
I used to hear from people who claimed that climate change in the 20th century was caused by solar activity, we’ve seen steadily increasing sunspot cycles, therefore we shouldn’t concern ourselves with what those darn fuzzy-headed climatologists are claiming.
But they were at a loss for words when I would show them evidence that 20th centery solar activity peaked in mid-century (remember cycle 19?), and the cycles are not getting increasingly larger.
So what came next? I started hearing from the same crowd that solar activity is declining, and therefore since we KNOW global temperature is determined by sunspots (they tend toward black-and-white thinking), we have nothing to worry about.
Of course the problem (figuring out climate influences) is a complex one, and ripe for manipulation and obfuscation by folks who want to bad-mouth the concept of climate being influenced by human activity.
Regarding sunspots causing warming, it is not proven. Also, we actually do not have a lot of sunspot data, at least in terms of millenia. Accurate sunspot data only goes back a couple of centuries, and with each sunspot cycle only lasting between 9 and 14 years, we barely have 23 cycles to analyze.
The global warming skeptics keep mentioning the Maunder Minimum and record cold temperatures in Europe. But I think they may be cherry-picking the data, because while it was colder on average in Europe during those decades, it wasn’t colder on average in other places.
Recently I received a flood of email concerning a non-science (or nonsense) article in Investors Business Daily claiming that we are headed for decades of no sunspot activity, another Maunder Minimum, and again, global cooling instead of warming.
They quoted Dr. Kenneth Tapping of the Penticton Observatory in British Columbia (source of the daily 10.7 cm solar flux readings) to advance this theory. They also claimed that the bottom of this solar cycle was unusual, and the new cycle was way overdue. (this cycle bottom, by the way, is nothing unusual)
I thought some of the statements by Tapping didn’t really sound like him, so I emailed him about the article. His response was something like “OMG this has been the worst 2 weeks of my life!”
Apparently a woman had called him a month earlier, kept him on the phone for about 90 minutes, and kept running through a bunch of what-if scenarios, talking about climate and solar cycles. Of course, Dr. Tapping is not a climatologist, he is an astronomer.
He cannot remember who she was or who she worked for, but apparently she must not have liked what she heard, so she just started making shit up.
Tapping says the article completely twisted what he said, taking statements out of context, and he thinks even fabricating statements.
Another interesting thing about the article besides its junk-science promotion, is that there is no byline. No author claims responsibility for this piece.
Another interesting thing is that as soon as the article appeared, I could google any phrase from the piece and find links ALL OVER the conservative blogosphere. Right wing bloggers were citing this article as scientific proof that the earth will be cooling, not warming. Of course, they put this among smart-assed remarks making fun of Al Gore and granola-eating, gaia-worshiping tree-huggers.
Remember my comment about obfuscation with large amounts of complex data? Remember when the Tobacco Institute was funding “scientific” research that “proved” there was no correlation between tobacco smoke and lung cancer?
Well, take a look at this, from CBC:
http://www.cbc.ca/fifth/denialmachine/index.html
One of the people they interviewed was a scientist, who is a statistician, not a climatologist, who claims there is NO correlation between climate change and human activity. He also claims he has NO IDEA who is funding his research.
But then the program gives you a real surprise. They show footage of him in past decades making similar claims about a major health issue for which there was plenty of evidence and an emerging scientific consensus that eventually was accepted as fact.
And guess what he said back then? NO IDEA where his funding came from.
I wonder who the woman was who interviewed Dr. Tapping? There is no byline. Was it generated by some well-funded right-wing think tank, feeding stories into the echo-chamber of right-wing media? Maybe CBC can investigate that. Of course, many people in this country will just dismiss any investigation as some sort of nefarious commie-pinko plot. After all, that CBC program wasn’t done by good, god-fearing, old glory saluting AMERICANS…it was those god-damned CANADIANS! ;–)
OK, gotta get out of here and jump in the car with my mobile HF setup. I’m driving to the top of a nearby hill to take advantage of the suddenly increased sunspot activity this week.
Thanks for letting me rant.
Dalton Minimum Watcher on March 30, 2008 at 6:27 am: 4
So! taddy. YOUR explanation for the Argo system finding ocean Cooling over the past five years? Your explanation for the Earth cooling despite CO2 continuing to rise?
Tad Cook on March 30, 2008 at 6:27 pm: 5
SO, Dalty! I am not a climatologist, and neither is Dr. Tapping. I am talking about the junk science used by non-climatologists, in which they make up shit about sunspot activity. If their evidence is so good, why do they lie?
Bob on April 8, 2008 at 7:31 am: 6
Do some research on Solar Inertial Momentum. The question is not whether we are headed for a period of low solar activity - the question is what will the impact be on the climate?
b2b on April 8, 2008 at 6:41 pm: 7
Ah, Tad, let’s be careful, you wouldn’t want to be the pot calling the kettle black would you?
http://www.nationalpost.com/news/canada/beyondbelief/Story.html?id=165020
We should all develop some scientific humility with respect to climate change. Since we can’t say for certain if it is even occurring, nor why it might be changing, nor which way it might be changing, nor whether that would be good or bad for Man and Earth, should we not perhaps just take the advice in this letter, and learn to adapt, until we know more?
Guy Grierson on April 15, 2009 at 1:47 pm: 8
Talk about junk science! Climate change computer models, constructed from very uncertain data, purport that changes in the sun are not part of climate change. Lets see, the sun is the size of a beachball compared to the earth the size of a pea, in an uncontrolled multim million degree fusion reaction. It provides all of the energy that keeps the earth from being close to absolute zero, that is -457 degrees farenheit. But the pinheads on the pea think they are somehow controlling the climate change!!! That is junk science. There is no reasonable scientist who could think that the sun is or should be constant! And we take measurements now from several satellites, and the energy from the sun is waning, and in a very, very complex way. Perhaps as part of some natural cycle. But the point is, the climate should not and never has been constant, which is the underlying assumption of the computer models. Because it is pretty impossible for that fusion reaction to stay absolutely constant, as we observe with the variations in the sunspots, flares, solar wind, and spectral radiation emanating from the sun. But the junk science global warming zealots cannot accept this. So they spend copious amounts of energy in denial about any source of climate change other than CO2. Closed minds do not make for good science.
Leon on June 14, 2011 at 9:18 pm: 9
Looks like the sun is giving us a surprise. Well I guess it might be no surprise to Ivanka Charvatova. I read that the Medieval warming (warmer than current times) descended destructively into the Little Ice Age, during solar quiet, and that the Medieval warming included South America and China besides being felt in Europe. Now this: http://www.space.com/11960-fading-sunspots-slower-solar-activity-solar-cycle.html
Keith J. Trawick on July 24, 2011 at 1:13 pm: 10
“The sun will be quite for a while.” Are you sure you don’t mean “quiet”?