Quasi-annual variations may hold clues to space weather
Credit Image by NASA
BOULDER -The Sun undergoes a type of seasonal variability with its activity waxing and waning over the course of nearly two years, according to a new study by a team of researchers led by the National Center for Atmospheric Research (NCAR). This behavior affects the peaks and valleys in the approximately 11-year solar cycle, sometimes amplifying and sometimes weakening the solar storms that can buffet Earth’s atmosphere.
The quasi-annual variations appear to be driven by changes in the bands of strong magnetic fields in each solar hemisphere. These bands also help shape the approximately 11-year solar cycle that is part of a longer cycle that lasts about 22 years.
“What we’re looking at here is a massive driver of solar storms,” said Scott McIntosh, lead author of the new study and director of NCAR’s High Altitude Observatory. “By better understanding how these activity bands form in the Sun and cause seasonal instabilities, there’s the potential to greatly improve forecasts of space weather events.”
The overlapping bands are fueled by the rotation of the Sun’s deep interior, according to observations by the research team. As the bands move within the Sun’s northern and southern hemispheres, activity rises to a peak over a period of about 11 months and then begins to wane.
The quasi-annual variations can be likened to regions on Earth that have two seasons, such as a rainy season and a dry season, McIntosh said.
The study, published this week in Nature Communications, can help lead to better predictions of massive geomagnetic storms in Earth’s outer atmosphere that sometimes disrupt satellite operations, communications, power grids, and other technologies.
The research was funded by NASA and the National Science Foundation, which is NCAR’s sponsor.
A “jet stream” in the Sun
The new study is one of a series of papers by the research team that examines the influence of the magnetic bands on several interrelated cycles of solar magnetism. In a paper last year in Astrophysical Journal, the authors characterized the approximately 11-year sunspot cycle in terms of two overlapping parallel bands of opposite magnetic polarity that slowly migrate over almost 22 years from high solar latitudes toward the equator, where they meet and terminate.
McIntosh and his co-authors detected the twisted, ring-shaped bands by drawing on a host of NASA satellites and ground-based observatories that gather information on the structure of the Sun and the nature of solar flares and coronal mass ejections (CMEs). These observations revealed the bands in the form of fluctuations in the density of magnetic fuel that rose from the solar interior through a transition region known as the tachocline and on to the surface, where they correlated with changes in flares and CMEs.
In the new paper, the authors conclude that the migrating bands produce seasonal variations in solar activity that are as strong as the more familiar 11-year counterpart. These quasi-annual variations take place separately in both the northern and southern hemispheres.
“Much like Earth’s jet stream, whose warps and waves have had severe impact on our regional weather patterns in the past couple of winters, the bands on the Sun have very slow-moving waves that can expand and warp it too,” said co-author Robert Leamon, a scientist at Montana State University. “Sometimes this results in magnetic fields leaking from one band to the other. In other cases, the warp drags magnetic fields from deep in the solar interior, near the tachocline, and pushes them toward the surface.”
The surges of magnetic fuel from the Sun’s interior catastrophically destabilize the corona, the Sun’s outermost atmosphere. They are the driving force behind the most destructive solar storms.
“These surges or ‘whomps’ as we have dubbed them, are responsible for over 95 percent of the large flares and CMEs–the ones that are really devastating,” McIntosh said.
The quasi-annual variability can also help explain a cold-war era puzzle: why do powerful solar flares and CMEs often peak a year or more after the maximum number of sunspots? This lag is known as the Gnevyshev Gap, after the Soviet scientist who first reported it in the 1940s. The answer appears to be that seasonal changes may cause an upswing in solar disturbances long after the peak in the solar cycle.
Researchers can turn to advanced computer simulations and more detailed observations to learn more about the profound influence of the bands on solar activity. McIntosh said this could be assisted by a proposed network of satellites observing the Sun, much as the global networks of satellites around Earth have helped advance terrestrial weather models since the 1960s.
“If you understand what the patterns of solar activity are telling you, you’ll know whether we’re in the stormy phase or the quiet phase in each hemisphere,” McIntosh said. “If we can combine these pieces of information, forecast skill goes through the roof.”
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About the article
Title: The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
Authors: Scott W. McIntosh, Robert J. Leamon, Larisza D. Krista, Alan M. Title, Hugh S. Hudson, Pete Riley, Jerald W. Harder, Greg Kopp, Martin Snow, Thomas N. Woods, Justin C. Kasper, Michael L. Stevens, and Roger K. Ulrich
Publication: Nature Communications
“If we can combine these pieces of information, forecast skill goes through the roof.”
Are any forecasts made or examples provided to demonstrate forecast skill?
File under “It is the sun stupid”
To every thing there is a season, and a time to every purpose under the heaven,
So the quasi-annual variation is the “season”? and the quasi-annual variation is 11 months-ish?
I am simply dumbfounded. All this time I was under the distinct impression that the science was settled and nothing new was ever going to discovered about the sun. What I found most interesting was :”the authors conclude that the migrating bands produce seasonal variations in solar activity that are as strong as the more familiar 11-year counterpart. “. Well, that is something indeed. I wonder. I wonder if this affects us?
If they could predict an increased probability of cme s hitting the Earth in say six months time, what effect would that have in the way that we handle them? None whatsoever would be my guess.
There doesn’t seem to be very much new here. Dr. Svalgaard can you help me out?
April 6, CME Forecast
These solar storms – are they caused by an excess of CO2?
It has been known for a very long time that solar activity comes in random ‘episodes’ of a bit less than a year in length. The classical example is cycle 14: http://www.solen.info/solar/cycl14.gif
The current cycle exhibits the similar pattern, although less distinct. Unfortunately, the episodes are not really periodic so are hard [impossible?] to predict. The paper is an example of the usual hype surrounding such ‘discoveries’
So what the pseudo-science has to say about it:
I wrote an article about 5-6 years ago, anticipating and providing some proof for the quasi-annual variations in the sunspot cycles:
http://www.vukcevic.co.uk/solarsubcycle.pdf
Got severely admonished by the Stanford solar supremo, nothing new about that.
“These surges or ‘whomps’ as we have dubbed them, are responsible for over 95 percent of the large flares and CMEs–the ones that are really devastating,” McIntosh said.
Devastating to what???
Who knows, when the actual paper is unavailable from NCAR, Nature Communications, or the Astrophysical Journal, as of five minutes ago. Why make a press release w/o it?
If anyone can find the paper please provide a link.
Gosh! They mean the sun has something to do with the weather, Maybe even climate. And here, I thought it was CO2.
As an aside, with thirteen authors for the piece that’s not many words to go round per author? ;o))
Nature works in cycles. Our limited powers of observation in the spatial and temporal phenomena dimensions blinds us and our evolved powers of survival-related intuition sees linear trends.
“The Sun undergoes a type of seasonal variability with its activity waxing and waning over the course of nearly two years..”
Oh Lord. We are going to have the numerologists coming out of the woodwork like termites again.
You watch, the tidal effects will stir up these storminesses and the storminesses will have such a long lasting and pervasive effect that all earthly climate change can be explained.
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Maybe if they get to credit themselves with these “discoveries” they will also (re)discover that each of the rest of the “myths” they purport on the warmist blogs also has a function in climate mechanics. Then CO2 will be brought into it’s correct perspective and dethroned as the omnipotent driver of mother Gaia’s future.
season on earth is controlled by the sun, and on the sun? what are the seasons of the sun? are there rainy and winter?
This current cycle is the first cycle that is clearly in the prolonged solar minimum cycle which is different from all of the solar cycles since the Dalton Solar Minimum. This cycle unlike others since the Dalton Solar Minimum started when the sun was in the midst of an extreme solar lull (which no one predicted) only to have a very extended weak solar maximum period but resulting in very few geomagnetic events here on the earth , to the way the solar polar fields are now evolving which is different from previous cycles, to at this current point in time seemingly fading away at a quite rapid rate.
so now for quite long,
The models are wrong.
So what caused the pause in the warming?
Look to the sun,
The way oceans run,
And the clouds, in complexity forming!
Thanks, Anthony.
Nothing about the Sun is boring, research is exiting.
I dislike the term “season”. It’s not an appropriate analogy.
Cycle would have been better.
The sun is increasingly a variable star.
Unfortunately, I find some things here a bit strange. We have a “band” of magnetic fields to the north and to the south and some times the “magnetic fields leak from one band to the other.” Leaks? And they found these bands by observing changes in the density of the “magnetic fuels?” And some how these bands “warp” magnetic fields from the interior of the Sun and push them to the surface? Is this really science I am reading? It does seem to go hand in hand with calling something “whomps” I would guess, but I can only surmise that all this wondrous information came from deciding what “stuff” does and modeling it on the computer to prove it, one “whomp” at a time, so to speak.
They don’t say! Next experts will be telling us that the Sun affects weather here on Earth, but not climate……..oh wait a minute they already have done!
Evokes the ENSO cycles here on earth. Now you see them, now you don’t.