[K6BW] Followup: 0'l Sol's Sneezin - purloined from QRP-L

Bill Smith hbcs at sonic.net
Wed Dec 6 19:14:43 EST 2006


Gang,

Last night at our Tuesday night get together, Bill, K6RMK reported hearing
the impact of the solar flare on the Earth.  He reported hearing the effect
of the shock wave, followed by popcorn sounds, evidence of proton
collisions.

Yesterday, the sun produced an X9 solar flare, *very* unusual for being near
the bottom of the solar minimum.  Today (6Dec) the sun produced another X6
flare.  This certainly suggests that active region #0930 will be bringing us
plenty of entertainment over the next two weeks as it rotates across the
surface of the sun.

For the *duration* of the flare events, HF can be disrupted by bursty and
continuum noise, plus enhanced D-layer ionization absorbing signals, if not
a temporary HF blackout.  However, once that bleeds off in an hour or two,
the D-layer will be back to normal and the E/F layers will remain ionized
above normal for the rest of your local daytime hours.  This of course makes
the E/F layers more reflective and raises the MUF.  Therefore, a good time
for QRPers to check the bands is an hour or so after a large flare until
local sundown for enhanced HF propagation.

Most of today we've also been in a major geomagnetic storm.  Believe it or
not, it has nothing to do with yesterday's X9 (or today's X6) flare.  The
Earth has simply run in to a high speed electron stream from a coronal hole.
This has exerted pressure against our magnetic field, compressing it, and
generating huge electrical currents causing high HF noise levels.  This will
subside by later in the day.

If the sun produces M or X class flares over the next few days, the coronal
mass ejection (CME) will begin to be pointed towards earth, meaning we can
expect a geomagnetic storm about two days following the flare event.  The
closer the solar flare is to the center of the sun, more the direct of a hit
we'll receive on earth.  Today's X6, being near the limb of the sun, will
probably give the earth only a glancing blow for a few hours of unsettled
conditions late friday.

The >10MeV proton count is high.  These protons tend to accumulate in the
polar regions (where the Earth's magnetic field is weakest).  This causes a
Polar Cap Absorption Event, meaning high absorption to HF signals for those
above 45-50 degrees latitude.  These same protons are what fuels auroral
displays.  Those in the higher latitudes are experiencing aurora now.

The moral of the story for QRPers:
1) Don't let reports of solar flares, geomagnetic storms, CME's keep you
  off the bands.  Much of this is of short term duration.
2) Enhanced HF propagation, including sporadic openings on 15, 10 and even
  6M can occur after a major flare for the rest of the day until sundown.
3) This includes possible north-south dx propagation at sundown due to
  gray-line propagation.  (If you do work McMurdo Sound, you better make
  the QSO a snappy one, though -hi).

Good luck and have fun on the bands.  It's not nearly as bad as it appears.
In fact, it really works in the QRPers favor.

72, Paul NA5N



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