Researchers discover new clues to determining the solar cycle

Written by Karen C. Fox, phys.org

Approximately every 11 years, the sun undergoes a complete personality change from quiet and calm to violently active. The height of the sun’s activity, known as solar maximum, is a time of numerous sunspots, punctuated with profound eruptions that send radiation and solar particles out into the far reaches of space. solar migration

However, the timing of the  is far from precise. Since humans began regularly recording  in the 17th century, the time between successive solar maxima has been as short as nine years, but as long as 14, making it hard to determine its cause. Now, researchers have discovered a new marker to track the course of the solar cycle—brightpoints, little bright spots in the  that allow us to observe the constant roiling of material inside the . These markers provide a new way to watch the way the magnetic fields evolve and move through our closest star. They also show that a substantial adjustment to established theories about what drives this mysterious cycle may be needed.

Historically, theories about what’s going on inside the sun to drive the solar cycle have relied on only one set of observations: the detection of sunspots, a data record that goes back centuries. Over the past few decades, realizing that sunspots are areas of intense magnetic fields, researchers have also been able to include observations of magnetic measurements of the sun from more than 90 million miles away.

“Sunspots have been the perennial marker for understanding the mechanisms that rule the sun’s interior,” said Scott McIntosh, a space scientist at the National Center for Atmospheric Research in Boulder, Colorado, and first author of a paper on these results that appears in the September 1, 2014, issue of the Astrophysical Journal. “But the processes that make sunspots are not well understood, and far less, those that govern their migration and what drives their movement. Now we can see there are bright points in the solar atmosphere, which act like buoys anchored to what’s going on much deeper down. They help us develop a different picture of the interior of the sun.”

Over the course of a solar cycle, the sunspots tend to migrate progressively lower in latitude, moving toward the equator. The prevailing theory is that two symmetrical, grand loops of material in each solar hemisphere, like huge conveyor belts, sweep from the poles to the equator where they sink deeper down into the sun and then make their way steadily back to the poles. These conveyor belts also move the magnetic field through the churning solar atmosphere. 

The theory suggests that sunspots move in synch with this flow – tracking sunspots has allowed a study of that flow and theories about the solar cycle have developed based on that progression. But there is much that remains unknown: Why do the sunspots only appear lower than about 30 degrees? What causes the sunspots of consecutive cycles to abruptly flip magnetic polarity from positive to negative, or vice versa? Why is the timing of the cycle so variable?

Beginning in 2010, McIntosh and his colleagues began tracking the size of different magnetically balanced areas on the sun, that is, areas where there are an equal number of magnetic fields pointing down into the sun as pointing out. The team found magnetic parcels in sizes that had been seen before, but also spotted much larger parcels than those previously noted—about the diameter of Jupiter. The researchers also looked at these regions in imagery of the sun’s atmosphere, the corona, captured by NASA’s Solar Dynamics Observatory, or SDO. They noticed that ubiquitous spots of extreme ultraviolet and X-ray light, known as brightpoints, prefer to hover around the vertices of these large areas, dubbed “g-nodes” because of their giant scale.

These brightpoints and g-nodes, therefore, open up a whole new way to track how material flows inside the sun. McIntosh and his colleagues then collected information about the movement of these features over the past 18 years of available observations from the joint European Space Agency and NASA Solar and Heliospheric Observatory and SDO to monitor how the last solar cycle progressed and the current one started. They found that bands of these markers – and therefore the corresponding large magnetic fields underneath – also moved steadily toward the equator over time, along the same path as sunspots, but beginning at a latitude of about 55 degrees. In addition, each hemisphere of the sun usually has more than one of these bands present.

McIntosh explains that a complex interaction of magnetic field lines may take place in the sun’s interior that is largely hidden from view. The recent observations suggest that the sun is populated with bands of differently polarized magnetic material that, once they form, steadily move toward the equator from . These bands will either have a northern or southern magnetic polarity and their sign alternates in each hemisphere such that the polarities always cancel. For example, looking at the sun’s northern hemisphere, the band closest to the equator – perhaps of northern polarity – would have  lines that connect it to another band, at higher latitudes, of southern polarity. Across the equator, in the bottom half of the sun, a similar process occurs, but the bands would be an almost mirror image of those across the equator, southern polarity near the equator and northern at higher latitudes. Magnetic field lines would connect the four bands; inside each hemisphere and across the equator as well.

While the field lines remain relatively short like this, the sun’s magnetic system is calmer, producing fewer sunspots and fewer eruptions. This is solar minimum. But once the two low-latitude marching bands reach the equator their polarities essentially cancel each other out. Abruptly they disappear. This process, from migratory start to finish at the equator takes 19 years on average, but is seen to vary from 16 to about 21 years.

Following the equatorial battle and cancellation, the sun is left with just two large bands that have migrated to about 30 degrees latitude. The  from these bands are much longer and so the bands in each hemisphere feel less of each other. At this point, the sunspots begin to grow rapidly on the bands, beginning the ramp-up to solar max. The growth only lasts so long, however, because the process of generating a new band of opposite polarity has already begun at high latitudes. When that new band begins to appear, the complex four-band connection starts over and the number of sunspots starts to decrease on the low-latitude bands.

In this scenario, it is the magnetic band’s cycle – the lifetime of each band as it marches toward the equator – that truly defines the entire solar cycle. “Thus, the 11-year solar cycle can be viewed as the overlap between two much longer cycles,” said Robert Leamon, co-author on the paper at Montana State University in Bozeman and NASA Headquarters in Washington.

The new conceptual model also provides an explanation of why sunspots are trapped below 30 degrees and abruptly change sign. However, the model creates a question about a different latitude line: Why do the magnetic markers, the brightpoints and g-nodes, start appearing at 55 degrees?

“Above that latitude, the solar atmosphere appears to be disconnected from the rotation beneath it,” said McIntosh. “So there is reason to believe that, inside the sun, there’s a very different internal motion and evolution at high latitudes compared to the region near the . 55-degrees seems to be a critical latitude for the sun and something we need to explore further.”

Solar cycles theories are best tested by making predictions as to when we will see the next solar minimum and the next solar maximum. This research paper forecasts that the sun will enter solar minimum somewhere in the last half of 2017, with the sunspots of the next cycle appearing near the end of 2019.

“People make their predictions for when this solar cycle will end and the next one will start,” said Leamon. “Sometime in 2019 or 2020, some people will be proved right and others wrong.”

In the meantime, regardless of whether the new hypothesis provided by McIntosh and his colleagues is correct, this long term set of bright points and g-node locations offers a new set of observations to explore the drivers of solar activity beyond only sunspots. Inserting this information into solar models will provide an opportunity to improve simulations of our star. Such advanced models tell us more about other stars too, leading to a better understanding of similar magnetic activity on more exotic, distant celestial counterparts.

Read more at: phys.org/news

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Comments (16)

  • Avatar

    D o u g

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    Well you “think” incorrectly (as usual) Claudius.

    Of course my explanations “make no sense” to you. They are directed to intelligent readers with a genuine understanding of thermodynamics and radiative heat transfer. As distinct from many PSI writings, they contain correct physics. But you are so brain washed with pseudo “fissics” that you simply do not have a clue.

    So when, and only when, you and Pat can contribute a sensible, reasoned response discussing the physics in what I write I may entertain your discourse.

    In the meantime feel free to write to each other and see if anyone else agrees with you.

  • Avatar

    Claudius Denk

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    I think Doug suffers from a pathological inability to distinguish between temperature and energy. That’s why he is so obsessed with Loschmidt. And that is why his long-winded, repetitive explanations make no sense.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]In the Appendix of my book, of course.[/quote]

    Only you Doug Cotton could imagine that a demonstration of claims, could appear in the appendix of a book (mad magazine) of the claimer!!
    Where is your demonstration?

  • Avatar

    D o u g

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    In the Appendix of my book, of course.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]Speak for yourself, Pat.[/quote]

    I am. Where is your demonstration?

  • Avatar

    D o u g

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    Speak for yourself, Pat.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]Go and edit Wikipedia, Pat Obar, and explain why Nobel Prize winner, Max Planck was wrong because apparently reality is the way you see things with your school boy imaginings.

    http://en.wikipedia.org/wiki/Max_Planck#Black-body_radiation%5B/quote%5D

    Planck was correct, Maxwell was correct. Both could demonstrate their theorems. Doug Cotton is incorrect. Cotton cannot demonstrate any of his claims. Cotton cannot even determine how his claims may be demonstrated or falsified. Cotton only handwaves nonsense!

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]Doug Cotton has measurements of 30 years of temperature data from three continents which show, with statistical significance that water vapour cools because more moist regions have lower mean daily maximum and minimum temperatures than do drier regions at similar latitudes and altitudes. These measurements smash the greenhouse.

    You, Pat Obar, have no understanding of the state of thermodynamic equilibrium and why it necessarily has a temperature gradient. Every bit as much as gravity forms a density gradient, it also forms a temperature gradient. There’s $5,000 if you can prove this does not happen in all significant planetary tropospheres – and that water vapour warms.

    There are numerous published experiments with measurements of radiation from the Earth’s surface. Every time you point an IR thermometer at the surface, even from various altitudes, it “knows” it is receiving radiation from which it gives a temperature.

    Frankly you put your foot in it every time you dabble in physics Pat. When you’ve had over 50 years’ experience in studying and teaching physics, as I have Pat, then get back to me. But don’t expect me not to see through your guff in the meantime. No one pulls wool over Cotton’s eyes, my friend.[/quote]

    So you admit you have no measurement of radiative flux from the surface outward.

    You may have many years of nonsense surface temperature, or near surface temperatures determined by others, with absolutly nothing to indicate any flux outward from the surface.

    You can only flap arms and claim the same as warmists, and ClimAstrologists. You simply have no evidence of what you claim.

  • Avatar

    D o u g

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    Doug Cotton has measurements of 30 years of temperature data from three continents which show, with statistical significance that water vapour cools because more moist regions have lower mean daily maximum and minimum temperatures than do drier regions at similar latitudes and altitudes. These measurements smash the greenhouse.

    You, Pat Obar, have no understanding of the state of thermodynamic equilibrium and why it necessarily has a temperature gradient. Every bit as much as gravity forms a density gradient, it also forms a temperature gradient. There’s $5,000 if you can prove this does not happen in all significant planetary tropospheres – and that water vapour warms.

    There are numerous published experiments with measurements of radiation from the Earth’s surface. Every time you point an IR thermometer at the surface, even from various altitudes, it “knows” it is receiving radiation from which it gives a temperature.

    Frankly you put your foot in it every time you dabble in physics Pat. When you’ve had over 50 years’ experience in studying and teaching physics, as I have Pat, then get back to me. But don’t expect me not to see through your guff in the meantime. No one pulls wool over Cotton’s eyes, my friend.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]To help others understand what Pat is overlooking, I’ll explain in more detail. He is referring to the “ideal gas” thought experiment in which Loschmidt postulated that there would be a temperature gradient due to the effect of gravity on the motion of molecules between collisions. Indeed there is such a temperature gradient and it is the state of thermodynamic equilibrium. But this is only discussing non-radiative diffusion/conduction processes that are involved in the formation of this temperature gradient.[/quote]

    I am sure you wish others to understand, but only the nonsense of your fantasy. I do no thought problems. I only measure and attempt to explain the results of such measurement. Doug Cotton has no measurement whatsoever. Only hand waving!

    Loschmidt insisted on an atmospheric thermostatic gradient that is measured and maintained somehow.
    Maxwell insisted that the troposphere is thermodynamically isothermal, because of the Clausius Seconhd Law of thermodynamics, concerning spontaneity. Both are scientificaly and physically correct.

    [quote]But these surfaces can and do still lose energy by radiation. So, if you correctly argue that there is no net non-radiative energy transfer by non-radiative processes at the interface, then you leave yourself with unbalanced energy losses by radiation.[/quote]

    You cannot demonstrate any radiative exit flux from the surface of Earth. You can only parrot the ClimAstrologists fakery that everything radiates according to its own temperature raised to the fourth power. Where are your measurements of any exit flux.

  • Avatar

    D o u g

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    To help others understand what Pat is overlooking, I’ll explain in more detail. He is referring to the “ideal gas” thought experiment in which Loschmidt postulated that there would be a temperature gradient due to the effect of gravity on the motion of molecules between collisions. Indeed there is such a temperature gradient and it is the state of thermodynamic equilibrium. But this is only discussing non-radiative diffusion/conduction processes that are involved in the formation of this temperature gradient.

    The Earth’s surface is indeed maintained at the existing temperatures by the supporting mechanism associated with the gravito-thermal effect, as is the Venus surface.

    But these surfaces can and do still lose energy by radiation. So, if you correctly argue that there is no net non-radiative energy transfer by non-radiative processes at the interface, then you leave yourself with unbalanced energy losses by radiation.

    You can only understand the complete energy balance if you understand how new energy absorbed in the cooler regions upsets the equilibrium and thus leads to thermal energy transferring up the temperature gradient, restoring thermodynamic equilibrium as it does so.

    Hence the complete answer to the 72 hours of cloud cover lies in understanding that the clouds absorb energy on the sunny upper side. That new energy passes through the cloud (by non-radaitive processes) and some eventually makes it into the surface to offset the net radiation loss by the surface which is not receiving solar radiation due to the cloud cover.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]And what is in my book is based on what Loschmidt said about the gravitationally induced temperature gradient. [/quote]

    Have you fond anyone interested in “your” book?
    Please answer the two questions if you can!
    Why would I try to explain anything to Doug Cotton, who refuses to understand anything, except being a nuisance?

  • Avatar

    D o u g

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    And what is in my book is based on what Loschmidt said about the gravitationally induced temperature gradient. Of course there’s no energy transfer when there is a state of thermodynamic equilibrium, because that is when entropy is already a maximum. But that does not negate the fact that any object (including the surface) which can cool must have an energy input to offset the energy lost in cooling. I’m not asking those who already understand the gravito-thermal effect to answer the question – I’m asking the typical AGW advocate who thinks it’s all about radiation.

    Turn off the Sun and the whole Earth system would cool right down. It is the Sun which keeps everything, even the core of the Moon, at the current temperatures. It does so by disturbing the state of thermodynamic equilibrium with new energy which can only raise the temperature of the relatively cooler regions, such as cooler than about 400K on Venus. Now you explain how the energy absorbed in the upper troposphere of Venus subsequently causes the surface to warm back up again during the Venus day by the 5 degrees which it cooled during te Venus night.

  • Avatar

    Pat Obar

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    [quote name=”D o u g”]We intuitively think that Earth’s surface temperature will indeed vary up and down if the solar intensity varies likewise. And it does, but why? Does not all that nuclear energy generated in the core keep the core and perhaps the surface warm? Well, no, it doesn’t, and the core and surface would be just as hot without energy generation. The Moon gives us a clue.

    [b]So here’s a climate question very, very few can answer, least of all the AGW hoaxers:[/b]

    In the afternoon of a warm sunny day the surface temperature at some location on Earth may well cool by, say, 2 degrees per hour. Let’s say the next three days have intense cloud cover all day long, so not a ray of sunshine strikes the surface for 72 hours. Does the surface cool by 72 x 2 degrees? Of course not. But, suppose the clouds are 3Km above at a temperature that is initially 20 degrees colder than the surface. No amount of radiation from the clouds is going to stop the surface cooling down to the same temperature as the clouds. But it doesn’t. The 20 degree temperature difference is maintained to within a few degrees. But how does the surface receive an energy input to offset the energy losses which we know it could experience and cool by 2 degrees per hour?

    I’ll give you the answer in a few days, but think about it first. I’ll discuss any suggestions put forward. Remember, we are looking for the source of the necessary energy and the process by which the energy gets into the surface.[/quote]

    Who is this “we” of which you speak? Why do “you” think the surface should cool if the atmosphere with a temperature gradient is thermodynamically an isotherm, as agreed upon by Maxwell and Loschmidt long ago? Isotherm is when a thermally conductive mass has no spontaneous heat transfer. We are not looking for the source of the necessary energy. You Doug have no answers! never have never will!

  • Avatar

    D o u g

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    We intuitively think that Earth’s surface temperature will indeed vary up and down if the solar intensity varies likewise. And it does, but why? Does not all that nuclear energy generated in the core keep the core and perhaps the surface warm? Well, no, it doesn’t, and the core and surface would be just as hot without energy generation. The Moon gives us a clue.

    [b]So here’s a climate question very, very few can answer, least of all the AGW hoaxers:[/b]

    In the afternoon of a warm sunny day the surface temperature at some location on Earth may well cool by, say, 2 degrees per hour. Let’s say the next three days have intense cloud cover all day long, so not a ray of sunshine strikes the surface for 72 hours. Does the surface cool by 72 x 2 degrees? Of course not. But, suppose the clouds are 3Km above at a temperature that is initially 20 degrees colder than the surface. No amount of radiation from the clouds is going to stop the surface cooling down to the same temperature as the clouds. But it doesn’t. The 20 degree temperature difference is maintained to within a few degrees. But how does the surface receive an energy input to offset the energy losses which we know it could experience and cool by 2 degrees per hour?

    I’ll give you the answer in a few days, but think about it first. I’ll discuss any suggestions put forward. Remember, we are looking for the source of the necessary energy and the process by which the energy gets into the surface.

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