© NASAA 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.
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.
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."
© NASAThis diagram of the Sun's internal structure shows the Sun's major parts, including the jet streams that are the subject of today's telecon. The jet streams extend deep into the Sun, to the base of the solar convective zone.
Because it flows beneath the surface of the sun, the jet stream is not directly visible. Hill and Howe tracked its hidden motions via helioseismology. Shifting masses inside the sun send pressure waves rippling through the stellar interior. So-called "p modes" (p for pressure) bounce around the interior and cause the sun to ring like an enormous bell. By studying the vibrations of the sun's surface, it is possible to figure out what is happening inside. Similar techniques are used by geologists to map the interior of our planet.
In this case, researchers combined data from GONG and SOHO. GONG, short for "Global Oscillation Network Group," is an NSO-led network of telescopes that measures solar vibrations from various locations around Earth. SOHO, the Solar and Heliospheric Observatory, makes similar measurements from space.
"This is an important discovery," says Dean Pesnell of NASA's Goddard Space Flight Center. "It shows how flows inside the sun are tied to the creation of sunspots and how jet streams can affect the timing of the solar cycle."
There is, however, much more to learn."We still don't understand exactly how jet streams trigger sunspot production," says Pesnell. "Nor do we fully understand how the jet streams themselves are generated."
To solve these mysteries, and others, NASA plans to launch the Solar Dynamics Observatory (SDO) later this year. SDO is equipped with sophisticated helioseismology sensors that will allow it to probe the solar interior better than ever before.
"The Helioseismic and Magnetic Imager (HMI) on SDO will improve our understanding of these jet streams and other internal flows by providing full disk images at ever-increasing depths in the sun," says Pesnell.
Continued tracking and study of solar jet streams could help researchers do something unprecedented--accurately predict the unfolding of future solar cycles.
Click
here for a movie that 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.
Comment: This article sounds very much like a public relations attempt to salvage the colossal computer model failures that predicted a super cycle for solar cycle 24.
Recall this recent article on SOTT:
Solar cycle computer model with 98 percent forecasting accuracy a complete failureThe basic reality is that the modelers do not know what is going on. We only understand the science to a given point and beyond that we are learning. The problem is that so many in the scientific community now run on political energy and saving face as long as they can is more important than being honest about what we do and do not know.
This article is being mentioned on other sites as well. Here is a comment from the
Watts Up With That site from a leading solar researcher,
Leif Svalgaard:
Leif Svalgaard :
This press release is just NASA PR-machine hype. We have not 'solved' the problem. Even if we assume that the 'jetstream' has anything to do with the generation of spots [and I personally think it is the other way around] we have just moved the problem [rather than solving it] because now the question is "why was it slower?" Furthermore the 'critical 22 degrees' is not based on anything other than having happened once before.
What we have is a well-orchestrated CYA attempt: our [i.e. NASA-supported] models [predicting a super-cycle] were thwarted by this strange delay of the oscillation, but are basically correct [I think not].
FYI, 'CYA' is an acronym for Cover Your A##.
And another commenter from the
Solar Science blog:
John A :
Wow. Even Leif thinks its a dubious correlation at best.
I have two points to make about predictions about the current Solar Cycle:
1. Predictions about the next solar cycle have been persistently wrong.
2. Solar physicists are ignoring the wrong predictions without explanation rather than dealing with their failures.
It ain't science, folks. Its guessing. One day someone will get lucky and lead an entire science astray.
A more general observation is that predicting the future is exactly what it used to be - very, very difficult to pull off unless you can induce amnesia in your audience or appeal to their venality or both.
I suppose that could be the theme of the blog. It didn't start off that way, but I'm depressed that solar physicists don't appear to be addressing the failures of their models.
You can search SOTT for 'sunspot' or 'solar' and read many articles and papers on what is currently up with the sun.
Here is a good place to start:
A Cheshire Cat - Will Sunspots disappear entirely by 2015?
... no one took credit for figuring out why Y2K didn't happen. These guys deserve a hand!