[South Florida DX Association] Solar Flare

[NPAlex at aol.com]

I expect most of you have experienced the effects of the recent solar flare  
on the HF bands.  I think the following dissertation by NA5N to be very  
informative, and puts some "dimension" the energy levels and potential  effects.
 
Regards,
Norm W4QN
 
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From: na5n at zianet. com <----------- - PAUL NA5N  Ph.D.

Gang,
I was disappointed. As active region neared the center of  the sun, it 
went very quiet past day or so. Then ... from a B1 background  level, 
an X3.4 solar flare occured a couple of hours ago as I write this ...  
13DEC 0214UTC = 12DEC 2114EST/1914MST

This looks as if it could be a  biggie, and certainly plenty of 
entertainment over the next 2-3 days.  Energetic protons >100MeV 
began arriving at Earth less than an hour  later, traveling a good 
fraction of the speed of light.

>30MeV is  considered ionizing radiation.
> On the sunlit side of earth right now,  the D-layer
>is highly ionized, causing a total HF blackout to  20MHz,
>though subsiding a bit in the past 30 minutes to around  15MHz.
>Even here on the dark side of the planet, I hear very  few
>signals between the AM broadcast band (mostly groundwave  stations
>right now) to about 5.5MHz.

There is no evidence that  this ionizing radiation has reached the 
earths surface, known as a  ground-level event or GLE. On the 
otherhand, these protons are also hitting  the earth on the sun facing 
side of the earth, so the detectors in the U.S.  are kind of worthless 
right now. The resulting radiation is more of an  uppper atmosphere 
effect which cause concern to the airlines for passenger  radiation 
exposure and possible electronic failures.

It also makes  you wonder what concerns there might be inside of NASA 
regarding the Space  Shuttle astronauts, not having much of the 
Earth's atmosphere to shield  them. Energetic protons flying through 
integrated circuits can cause  junction failures, an additional 
concern.

These protons enter the  atmosphere, producing secondary particle 
collisions that produces increased  radiation levels in the upper 
atmosphere. When the immediate radiation storm  subsides, the E/F 
layers on the sunlit side of the earth will be very  reflective with 
an above normal MUF.

These protons are also entering  the polar regions which have to be
generating some spectacular aurora right  now up north. Not to 
mention a strong Polar Cap Absorption event, which has  the same 
effect as a near HF blackout for those in the higher  latitudes.

When the sun rises tomorrow over the Americas, the energetic  protons 
will ionize the atmosphere above our heads, making our E/F layers  
more reflective and a higher MUF, even though the solar flare is long  
over. However, it probably won't be enough to ionize the D-layer ...  
meaning tomorrow during the day (particular morning hours U.S.) is a  
good time to get on the air with a higher MUF and a quiet D-layer. 
Since  the E/F layers EAST of us will still be active, it could be 
favorable for  strong east-west paths into Europe QRP.

GEOMAGNETIC STORM.
This solar  flare occured smack in the middle of the sun ... the 
absolute ideal position  for a coronal mass ejection (CME) to deliver 
a full blow to the Earth.  Region 0930 is centered both in longitude 
and latitude, meaning the CME will  hit us almost directly, AND the 
full force of the CME will ride along the  plane of the Interplantary 
Magnetic Field (IMF). In short, we'll get a  fairly strong and direct 
hit in a day or two, which will no doubt trigger a  MAJOR, if not a 
SEVERE geomagnetic storm. This is NOT a "glancing blow"  event -hi.

WHEN WILL IT HIT?
NOAA doesn't give much of a prediction,  other than to say "on 14-15 
DEC." Of course, much of that is due to the SOHO  satellite being 
partially inoperative right now, so images and trajectory of  the CME 
can not be made.

So, let's figure it out  ourselves.

The speed of the shockwave from the CME was measured at  0244UTC at 
1532km/s, or a fairly strong shockwave (anything >1000km/s is  
considered a major shockwave).

1532km/s x 60 sec. x 60 min. =  5.5^6km/hr
With the sun 150,000,000km away, divided by 5.5^6km/hr = 27hrs  travel 
time.However, the shockwave slows down as it travels away from the  
sun, with an ESTIMATE of about 85% (this is the biggest uncertainty 
in  calculating arrival time. However, since it is traveling along 
the IMF  fairly directly, I'm going to stick to the fastest 85%  
estimate).

Therefore, 85% slowing of 27hrs = 32hrs = 1d 8h travel  time
Flare 13DEC 02UTC + 1d 8h = 14DEC 1000UTC = 14DEC  0500EST/0300MST

Thus, we can expect the shockwave to arrive, and the  geomagnetic 
storm to begin about sunrise 14DEC on the eastcoast US, and  
mid-morning to noon 14DEC in the UK/western Europe. Arriving at 85% 
of  its velocity, the shockwave should hit earth fairly directly at 
1532 x 85% =  1300km/s, or a fairly strong hit that will no doubt 
trigger a SEVERE  geomagnetic storm with K indices hitting 7, perhaps 
all the way to 9. Such a  severe compression of our magnetosphere 
will cause a long duration  geomagnetic storm, lasting 12-18 hours. 
There will be very high and bursty  noise levels leaving the bands 
fairly useless most of 14DEC.

Along  with the shockwave will be a wall of solar particles, many of 
which will be  funneled along the Earth's magnetic field into the 
polar regions, fueling a  strong aurora. If the >10MeV proton event 
is still continuing when the  shockwave hits, it will fuel the aurora 
further. In short, when the  shockwave hits, there could be very good 
auroras blowing fairly southward  wherever local midnight is when the 
shockwave occurs.

*IF* the  shockwave arrives early morning 14DEC as quasi-predicted 
above, it means  those of us in western Europe through the Americas 
will likely miss the  show. But ... we certainly won't miss the 
geomagnetic storm!

It is  always difficult to predict the nature and intensity of an 
arriving  shockwave (there are numerous factors that could skew the 
above calculated  arrival time by many hours). That's my guess and 
I'm sticking to it -hi. A  shockwave of 1300km/s has the *potential* 
of causing more severe problems  above lousy HF communications, such 
as problems with electrical systems.  Again, the potential is there, 
but no way of predicting anything  specific.

If the electrical power goes out somewhere - GET ON THE AIR. I  have 
1st hand experience of being on the air when the westcoast US went  
dark about 10 years ago. 40M was so quiet, it sounded like 2M over 
the  repeater! You'll just have to see what band has minimal noise 
for some  unique ground/skip propagation. Of course, that failure was 
not due to a  geomagnetic storm, so the noise from that was not 
present.

I always  enjoy sharing my knowledge on the solar phenomenon after a 
solar flare and  geomagnetic storm, but this is a unique opportunity 
to observe the effects  BEFORE it happens. By watching what happens 
over the next 2-3 days, with the  above information, it should 
strengthen your knowledge and confirm your  understanding on 
solar/geomagnetic storms. I can tell you, for those QRPers  who have 
followed these posts over the years, you have a far higher  
understanding than the vast majority of hams.

If I learn anything new  or interesting when I arrive at work tomorrow 
at the observatory, I'll pass  it on.

72, Paul NA5N