[K6BW] Interesting Discussion on the Sun

[Bill Smith]

This was purloined from the QRP-L e-mail group.  It is an interesting
interpretation of current sun conditions and NASA solar reporting.  As
implied below, 10 meters has been open recently!  It is also interesting
that we still don't have a solar minimum, although one may be declared as of
last April:

In case you haven’t noticed, our Sun has been extremely active past few
days with numerous M-class flares.  This has come from a large, quickly
growing sunspot now coming around the limb, called region 960.  At the
moment, it is causing little effect on Earth.  However, over the next week
as it rotates closer to the center of the sun, continued M-class flares
could trigger some strong geomagnetic storms.  The good news is the flares
are also giving short blasts of ionizing radiation to planet earth, which
can temporarily raise the MUF into the higher bands and raise the overall
solar flux.

So keep an eye on the solar activity at: http://www.sec.noaa.gov/today.html
... and get on the air following a flare until local sundown for possible
enhanced conditions.

In the middle of April 2007, I posted a summary of solar activity (or lack
of it), stating it appears the lack of 28-day variation in solar flux for
two months, and other factors, are strong indicators we were now at the
solar minimum.  In retrospect, it appears this may have been the case from
the dxlc solar flux plot.  The recent solar activity, and resumption of the
28-day variation in solar flux, strongly suggests the solar minimum indeed
was around March-April 2007 and we’re beginning to head into better days.

Yesterday’s (Saturday's) largest flare was an M7, quite respectable.
Already today (Sunday UTC) we’ve had an M9.  That’s only one notch away
from an X-class flare!  This intensity of flares is what you expect well
into the active sun.  Encouraging that this next solar cycle may be
beginning with a bang.

Actually, as I write this, the M9 flare is still in progress.  Notice how
the previous flare was a very short "spike" and the M9 is taking it’s
sweet time to decay.  This is known as a long-duration flare.  I am also
listening to Radio Netherlands right now on 9.9 MHz, and tuning around, I
hear no effects from this flare (no static crashes, ignition noise type
emissions, or fading effects).

Below are excerpts from today’s NOAA report with explanations for those so
interested:

> Joint USAF/NOAA Report of Solar and Geophysical Activity
> SDF Number 154 Issued at 2200Z on 03 Jun 2007

> IA.  Analysis of Solar Active Regions and Activity from  02/2100Z
> to 03/2100Z:  Solar activity reached high levels today. Region 960
> (S09E50) produced three M-class flares; an M2.4 at 03/0159 UTC, an
> M7.0 at 03/0212 UTC,

Today’s M9 flare occurred after this report.

> and an M4.5 with an associated 330 sfu Tenflare at 03/0641UTC.

330 solar flux units.  A Tenflare means the flare affected the 10cm, or 2880
MHz emissions from the sun where the daily solar flux is measured.
Normally, flares do not affect this frequency, nor the solar flux readings.
Indicating a Tenflare occurred simply means today solar flux reading was
contaminated by the flare and thus is the best, smoothed estimate.  This is
important to QRPers because the spike in solar flux, which is removed, does
show our E/F layers received higher than normal ionization.

> Region 960 also produced a C5.3 flare at 03/0928 UTC with an associated
> Type II radio sweep (speed 522 km/s).

This means this flare produced a measurable coronal mass ejection, or CME.
As the shockwave from the flare expanded outward through the magnetic field
lines of the disturbance, it produces radio bursts.  Measuring the frequency
of these bursts, known as Type II sweeps, allows solar scientists to
estimate the speed of the shockwave.  In this case, the shockwave was
estimated at 522 km/sec.  Not really very large.  When the shockwave speed
gets around 800 km/sec, that is usually sufficient to trigger a strong
geomagnetic storm.  Large flares near the center of the sun above 1000
km/sec. can trigger a severe geomagnetic storm and auroras.

> This event is not expected to be geoeffective.

Not geoeffective means this CME is not directed towards the earth, and thus
will not trigger a geomagnetic storm.  However, future flares from region
960, as it rotates closer to the center of the sun, will become geoeffective
... meaning a resulting flare and CME will very likely produce a geomagnetic
storm, particularly if the speed exceeds 800 km/sec. or so.

> Region 960 has been classified as a beta gamma delta magnetic group with
> an area of approximately 540 millionths.

The size of a sunspot region is measured by it’s total area of the sun’s
surface.  In this case, 540 millionths, which is actually quite large.
Being a beta gamma delta group means the region has very strong, compact
magnetic field lines around the disturbance.  This generally indicates that
further large flares are likely, which is why NOAA concludes their report
with ...

> Solar activity is expected to continue at moderate to high levels with a
> chance for an X-class flare from Region 960.

Most of the above terms are graphically described on the GQRP website, "The
Handiman's Guide to Solar Activity" (or something like that), at:
http://www.interalia.plus.com/SOLAR_HO.pdf

Imagine ... an X-class flare only a month or two after the likely solar
minimum (whenever NOAA gets around to declaring it so).

72 and gud DX,
Paul NA5N