ALL
EYES ARE ON THE SUN AFTER NOAA-LED SOLAR CYCLE 24 PANEL PREDICTS UPCOMING
PERIOD OF INTENSE SOLAR STORMS
April
26, 2007 — All eyes are on the sun (though not directly with the
naked eye) now that the NOAA-led Solar Cycle 24 Prediction Panel released
its official consensus solar cycle forecast at the Space
Weather Workshop in Boulder, Colo., yesterday. The
panel agreed that the Earth will soon experience the start of a period
of intense solar storms and the exact number of solar storms expected
will become clearer in time. The panel agreed that the Earth will soon
experience the start of a new cycle of solar storms and the expected intensity
of the upcoming cycle will become clearer in time.
“The
next 11-year cycle of solar storms will most likely start next March and
peak in late 2011 or mid-2012,” said Doug Biesecker, a solar physicist
from the NOAA Space Environment Center
in Boulder, Colo., who also chaired the NASA-funded 12-person panel.
Although
the effects of solar storms are often seen from
Earth as beautiful lights dancing in the night sky (i.e., the Northern
Lights or aurora borealis), looks can be deceiving. In reality, these
storms can carry tremendous power and travel at speeds up to 5 million
miles per hour. Solar storms have been known to knock out satellites,
power supplies, communications and navigation systems. Many of these effects
are transitory (and virtually invisible), but they can be very disruptive
and potentially dangerous — both to the systems themselves and in
turn the nation’s economy. Damage to these systems can also result
in secondary effects that can disrupt virtually every major infrastructure
dependant on them, including transportation, security and emergency response
systems, telecommunications and other wireless networks and electronic
equipment. Solar storms even create a biological threat to both astronauts
and people flying in aircraft at high altitudes and latitudes.
Therefore, the Solar Cycle 24 Prediction Panel’s forecast is being
used by various industry and government groups for planning purposes,
including power companies, communication networks, satellite manufacturers/operators
and airline flight planners. Unfortunately, the nation’s (and the
world’s) vulnerability to solar storms will only increase as we
become even more dependant on these technologies.
"As people become more dependent on space-based technology, the potential
far-reaching and dramatic impacts of space weather make our mission more
vital each day," said Bill Murtagh, a space weather forecaster at
the NOAA Space Environment Center in Boulder, Colo. "Accurate space
weather measurements and predictions are vital in mitigating the potential
impact of these storms."
“The
Space Environment Center’s space-weather alerts, warnings, and forecasts
are a critical component of NOAA’s seamless stewardship of the Earth’s
total environment, from the sun to the sea,” said retired Vice Adm.
Conrad C. Lautenbacher,
Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator.
The NOAA SEC is the nation’s first alert of solar activity and its
affects on Earth. Just as NOAA’s hurricane experts predict the upcoming
season of Atlantic storms and forecast individual hurricanes, the agency’s
space weather experts issue outlooks for the next 11-year solar “season”
and warn of storms occurring on the sun that could impact the Earth. Both
the NOAA National Hurricane Center
and SEC are among NOAA’s
nine National Centers for Environmental Prediction. SEC is also the
world warning agency of the International Space Environment Service, a
consortium of 11 member nations.
NOAA
Perspectives on the Solar Cycle 24 Forecast
“The
prediction process was much more challenging than the previous two solar
cycle forecasts because it was conducted much earlier in the cycle and
because of the wide array of predictions that needed to be reconciled
this time around,” stated Biesecker. In
all, the panel evaluating more than 40 predictions from 15 different nation
—
some predicting a small solar cycle
with as little as 42 sunspots, while others predicted a larger cycle with
up to 185 sunspots (which would nearly rival the record setting Cycle
19 observed in the 1950s).
“Since
we have not even reached the solar minimum or end of this solar cycle
[23], we were really pushing the envelope on this one,” said Biesecker.
“Solar cycle predictions are fairly reliable once the cycle is underway,
but prior to that time the predictions are less certain — although
equally important.”
“The predictions for the strength of Solar Cycle 24 had more than
a threefold difference among them — that's a tremendous range,"
says Murtagh. “Satellite design and
mission planning teams and other end users aren't always able to sort
through all the conflicting information, so it is up to the NOAA Space
Environment Center and the rest of the panel to come up with a single
official prediction upon which they can base their decisions.”
The
Science Behind the Predictions
Eleven-year
solar cycle forecasts predict the number of sunspots which will occur
during a given solar cycle, and sunspots are known to generate solar storms
that could potentially damage Earth systems. Like other long-term weather
forecasts, the solar cycle forecast does not predict the time, intensity
or duration of the solar storms. In this way, the solar cycle forecast
is very much like NOAA's seasonal hurricane outlook — the overall
level of activity for the season is forecast, but it doesn't predict the
specific time, intensity etc. of any given storm. That is covered by more
short-term space weather warnings issued by the NOAA the NOAA Space Environment
Center.
Each 11-year solar cycle consists of a solar maximum characterized by
a large number of sunspots (and solar storms) followed by a solar minimum
characterized by a smaller number of sunspots (and solar storms). Currently,
we are approaching the end of Solar Cycle 23 (a solar minimum) and are
on the heels of the start of Solar Cycle 24 (a solar maximum) —
so the topic on the minds of many people is the upcoming Solar Cycle 24,
its much anticipated solar maximum, and the number of solar storms it
will generate.
The
sun, like Earth, has seasons. The sun’s season is dictated by sunspots
and is known as the 11-year solar cycle. Sunspots occur when strong magnetic
fields emerge through the solar surface and allow the area to cool slightly,
thus making it appear as a dark spot in contrast to the even hotter sun
areas surrounding it. These magnetically disturbed regions are often the
source of large solar flares and coronal mass ejections from the sun.
At the beginning of each 11-year solar cycle, sunspots first appear at
high latitudes, but as the cycle continues, sunspots start emerging closer
to the equator and eventually stop forming all together as the cycle comes
to a close. Sunspots only last for a few weeks and are basically tangled
knots of magnetism generated by the sun's “inner dynamo” (i.e.,
the internal engine that powers/drives the sun). Throughout their life,
they decay, leaving behind weak magnetic fields as their 'remains.' Then
the sun’s “dynamo conveyor belt” (similar/analogous
to the one that drives ocean circulation on Earth, only it is made up
of gas on the sun) comes along and skims the surface of the sun, sweeping
up the magnetic fields of old, dead sunspots. The sunspot 'remains' are
dragged toward the poles and then down to a depth of 200,000 km where
the sun's magnetic dynamo (internal engine) reenergizes (essentially reincarnates)
them. Once the sunspot 'remains' are reincarnated, they become buoyant,
float back to the surface and create a brand new sunspot! It takes about
40 years to perform one complete circuit because the sun’s conveyer
belt only moves at a rate of about one meter per second. Researchers believe
the turning of the belt — especially the speed of the belt —
controls the sunspot cycle.
“It
is very dynamic, but basically the sun’s dynamo conveyer belt ‘recycles’
old sunspots from the current (or previous) solar cycle(s) to form seeds
which germinate new sunspots during next (upcoming) solar cycle,”
said Biesecker. “It is important to understand this, because the
sun’s ‘dynamo conveyor belt’ forms the basis for many
of the predictions used in the panels final Solar Cycle 24 forecast.”
Solar
Cycle 24 Predictions and the Prediction Process
“Although they are too complex to describe in detail here, there
are approximately six techniques used to predict the intensity of a solar
cycle,” said Biesecker. “The first three are based on statistics
and provide a sound historical baseline upon which to forecast future
cycles. The other three are based on physics and the sun’s dynamo
conveyer belt theory.”
Like the previous two solar cycle predictions, the final Solar Cycle 24
forecast was based on various combinations of several of these techniques,
however there was a tendency to rely less on statistical techniques and
more on physical techniques. It is important to note, however, that the
physical techniques are still relatively new, full of uncertainties and
part of a new field of research NASA is studying called helioseismology
(which is analogous to studying earthquakes on Earth).
“The
biggest question right now is when will we reach the solar minimum for
the current Solar Cycle [23], because that will essentially mark the start
of Solar Cycle 24,” said Biesecker. “It will serve as a good
‘litmus test’ for the validity of the models used in making
the final prediction. If a given model fails to accurately predict the
start of Solar Cycle 24, then it is likely that it will also fail to accurately
predict the timing, duration and intensity of the cycle’s peak [solar
maximum] and may therefore need to be eliminated from future [updated]
Solar Cycle 24 predictions. Therefore, as the cycle progresses and we
get more data, the panel will need to reevaluate its original predictions
and periodically [annually] update it over the next few years.”
According to Biesecker, we will have a better idea of what solar weather
has in store for us in late 2008 when Solar Cycle 24 is on the rise.
Relevant
Web Sites
NOAA
Space Weather Week - SEC's Annual User Conference
NOAA
Space Environment Center
Space
Weather Now
Today's Space
Weather
NOAA
Primer on Space Weather
Space
Environment Center Education Web site
THE
GROWING IMPORTANCE OF SPACE WEATHER INFORMATION
SOLAR
STORMS CAUSE SIGNIFICANT ECONOMIC AND OTHER IMPACTS ON EARTH
NOAA
SPACE ENVIRONMENT CENTER: EARTH'S FIRST DEFENSE AGAINST THE SUN'S FURY
Media
Contact:
Anatta,
NOAA Research, (303) 497-6288
Article by Julie Bedford (Editor, NOAA Magazine)
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