[KL7AA] WOAH! Look at the Sun

[Jim Larsen - AL7FS]

Paul's emails are always educational and informative.
-- 
Jim Larsen
Anchorage, Alaska
http://www.AL7FS.us/

[qrp-l.org] WOAH! Look at the Sun
Paul Harden, NA5N na5n at zianet.com
Mon Jun 4 02:12:10 CDT 2007

Gang,
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
begininning 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 occured 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 occured 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 (whenver NOAA gets around to declaring it so).

72 and gud DX,
Paul NA5N

http://mail.qrp-l.org/mailman/listinfo/qrp-l_qrp-l.org