[PPRAANet] X3 Flare 13DEC 02Z - Biggie!

[W0rw at aol.com]

NA5N @ VLA via w0rw
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 

@ VLA

PS - Just in case, I'd have a flashlight and a couple of candles ready :-)

PPS - Most electric grid failures occur with a shockwave >1600km/s