[PPRAANet] R3 Radio Blackout

[John Bloodgood]

You are correct, the absorption is less at higher frequencies.  During today’s X2 solar flare, the absorption at 15 MHz was around 5 to 6 dB, whereas at 30 Mhz it was around 2 dB.   This absorption tends to dissipate fairly quickly (several minutes/less than an hour) after an event.

With a solar event like a solar flare, there are several things that happen, but the two we focus most on are the X-Ray “flash” that hits us within 8’ish minutes of the flare and the ejecta (Coronal Mass Ejection) from the event hitting the Earth many hours later, anywhere from about 12 hours to a couple days. The X-Ray event is what causes the big red blob that you saw in the one image and causes the absorption and Radio Blackout (R-scale).  The ejecta arriving is what causes geomagnetic storming (G-scale) and often a lot of noise.

What happened today was that there had been a previous event that happened on the 15th and the CME (ejecta) was due to hit us around 2300 UTC today.  Coincidentally, at a little after 2000 UTC, another solar event happened, an X2 level flare. Within minutes, the much faster X-rays from today’s event hit the Earth before the ejecta from the previous event. This caused a brief R3 radio blackout.  The ejecta from the previous event should be hitting us any time now and will likely cause G1 to G2 level geomagnetic storming for the next several hours. During the storming, in the same screen as the red blob you saw earlier, you will see a lot of things like green zones around the poles.



John Bloodgood, KD0SFY

________________________________
From: ppraanet-bounces at mailman.qth.net <ppraanet-bounces at mailman.qth.net> on behalf of k3ilc <je_madsen at comcast.net>
Sent: Friday, February 17, 2023 4:23:02 PM
To: 'PPRAA' <ppraanet at mailman.qth.net>
Subject: Re: [PPRAANet] R3 Radio Blackout

I went on 10 meters, and the band sounded normal, except the signals
seemed a little bit weaker.
I think it's because the adsorption is much less at higher frequencies.
There were still some signals at the S9 level.

Jim Madsen
K3ILC

dphillipsdoc at gmail.com wrote:
> I was trying to log in to the Central Area Traffic Net 2030z on 14.345 and the whole band was completely dead.  Finally, was able to check in, but really tough.  By 2230 we were able to run the Western Area Traffic Net on 14.345 and things were a bit better.  My first time to experience this.
>
> Dave
>
> Dr. David M. Phillips
> NØDMPt/donate.html

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