I have just finished a talk with Christopher Balch from the Space Environment
Center, NOAA, regarding the super flare from 1955Z, 4-XI-2003. This flare
saturated the instruments on the observing satellites for about 13 minutes,
during the peak of the flare. This has made an accurate measurement of the
flare's intensity difficult. The instruments stopped at X17.4.
The scientists and engineers who designed the original sensor equipment back in
the 1970's had events that caused saturations at much lower levels. They
redesigned things to handle X17-class events, thinking that it would be enough.
This time, it was not.
Since we do not have any accurate record of flare intensity prior to the
1970's,
our perspective of this latest series of flares is somewhat limited.
Certainly,
X-class flares of this magnitude are not regular events. But, they certainly
are not unheard of. To pull out a rough estimate, but with very little
confidence on this number, on how often we might see such activity, we think
this is something we could see every 20 to 40 years.
Currently, as I write this, the Space Environment Center, who is the official
"last word" on what a flare's classification becomes, is finalizing their
analysis on this super flare. Chris has obtained two likely candidates: Using
a
standard log-normal fit analysis, the flare was X25. Using a result from an
individual from the University of Colorado, Boulder, who analyzed HESSI data on
the event ( http://hessi.ssl.berkeley.edu/ ), the flare was an X28. The SEC
has
a procedure that Chris is finalizing, and validating. He will announce the
final reading later today. Most likely, this flare will be somewhere between
the X25 and X30 levels.
Certainly, the geomagnetic storming of the last few weeks is one of the highest
in many years. It is officially number six on the scale of intensity in the
last 30 years. The two major sunspot groups, the number of flares, and the CME
activity makes this period the most active and intense of this solar cycle. We
have witnessed a truely spectacular historical moment.
What's coming down the line? I usually base my forecasts on a 27-day solar
rotation period. What happens today in terms of geomagnetic activity is
possibly what will occur 27 days from now. Of course, sunspot and coronoal
hole
activity might decline duing that rotation period. The outlook is that in
about
5 to 10 days, a sunspot group that had a lot of activity is going to rotate
back
around and start to influence space weather. But the big question is: Will
these huge sunspot groups that just left us retain enough energy to last the 27-
day rotation, to deliver another period of extreme solar weather?
NASA is planning to launch in November 2005 the "Stereo Mission" (
http://stereo.jhuapl.edu/mission/overview/overview.html ), which will place an
observing space craft leading the Earth's orbit, and another space craft
trailing the Earth, such that they will be able to see around the sun at what
is
coming and what has went. This certainly will become a major tool in our
forecasting of space weather, and propagation.
I will post my propagation forecast on http://prop.hfradio.org/ late today.
73 de Tomas, NW7US (AAR0JA/AAM0EWA)
--
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