Solar Mini-Max
 
June 10, 2014:  Years ago, in 2008 and 2009 an eerie quiet descended on the
sun.  Sunspot counts dropped to historically-low levels and solar flares
ceased altogether.  As the longest and deepest solar minimum in a century
unfolded, bored solar physicists wondered when "Solar Max" would ever return.
 
They can stop wondering. "It's back," says Dean Pesnell of the Goddard Space
Flight Center.  "Solar Max has arrived."
 
http://youtu.be/8Ha7X6dWVQE
 
A new ScienceCast video examines the curious Solar Max of 2014.  Play it
 
Pesnell is a leading member of the NOAA/NASA Solar Cycle Prediction Panel, a
blue-ribbon group of solar physicists who meet from time to time to forecast
future solar cycles.  It's not as easy as it sounds. Although textbooks call
it the "11-year solar cycle," the actual cycle can take anywhere from 9 to 14
years to complete.  Some Solar Maxes are strong, others weak, and, sometimes,
as happened for nearly 70 years in the 17th century, the solar cycle can
vanish altogether.
 
Pesnell points to a number of factors that signal Solar Max conditions in
2014: "The sun's magnetic field has flipped; we are starting to see the
development of long coronal holes; and, oh yes, sunspot counts are cresting."
 
Another panelist, Doug Bieseker of the NOAA Space Weather Prediction Center,
agrees with Pesnell: "Solar Maximum is here .. Finally." According to an
analysis Bieseker presented at NOAA's Space Weather Workshop in April, the
sunspot number for Solar Cycle 24 is near its peak right now.
 
They agree on another point, too:  It is not very impressive.
 
"This solar cycle continues to rank among the weakest on record," comments Ron
Turner of Analytic Services, Inc. who serves as a Senior Science Advisor to
NASA's Innovative Advanced Concepts program.  To illustrate the point, he
plotted the smoothed sunspot number of Cycle 24 vs. the previous 23 cycles
since 1755. "In the historical record, there are only a few Solar Maxima
weaker than this one."
 
As a result, many researchers have started calling the ongoing peak a
"Mini-Max."
 
http://science.nasa.gov/media/medialibrary/2014/06/10/plot.jpg
 
This plot prepared by Ron Turner of Analytic Services, Inc., shows the
smoothed sunspot number of Cycle 24 (red) vs. the previous 23 cycles since
1755.
 
Pesnell believes that "Solar Cycle 24, such as it is, will probably start
fading by 2015." Ironically, that is when some of the bigger flares and
magnetic storms could occur.  Biesecker has analyzed historical records of
solar activity and he finds that most large events such as strong flares and
significant geomagnetic storms typically occur in the declining phase of solar
cycles-even weak ones.
 
Indeed, this "Mini-Max" has already unleashed one of the strongest storms in
recorded history.  On July 23, 2012, a plasma cloud or "CME" rocketed away
from the sun as fast as 3000 km/s, more than four times faster than a typical
eruption. The storm tore through Earth orbit, but fortunately Earth wasn't
there. Instead it hit NASA's STEREO-A spacecraft, which recorded the event for
analysis.  Researchers now believe the eruption was as significant as the
iconic Carrington Event of 1859-a solar storm that set telegraph offices on
fire and sparked Northern Lights as far south as Hawaii. If the 2012
"superstorm" had hit Earth, the damage to power grids and satellites would
have been significant.
 
It all adds up to one thing: "We're not out of the woods yet," says Pesnell. 
Even a "Mini-Max" can stir up major space weather-and there's more to come as
the cycle declines.
 
Credits:
Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:
Science@NASA
 
Web Links:  Solar Cycle Progression -- NOAA Space Weather Workshop
 
 
Regards,
 
Roger

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