Hoping someone can enlighten me here. . . It seems the label “Radio Aurora” can be applied to two different things:
Emits radio frequencies around 150 kHz (what I would call a Radio Aurora); and
Reflects/scatters radio frequencies around 150 MHz and thereby enhances propagation (what I would just call an Aurora, leading to Auroral Propagation).
So I’m guessing that an alert on my weather webpage when Kp > 5, saying “144 MHz Radio Aurora Possible”, suggests that conditions might favour Auroral Propagation.
Not sure if this is what you want/mean but if you scroll down to the bottom of my web page there is some Propagation info there that I get from here HF Propagation and Solar-Terrestrial Data Website it’s not an alert but it’s useful. There has been a lift on most of this weekend for 2/70cm & 10/11m, hope this helps.
Yes, aurora will reflect radio waves, often from 50-200 MHz. As a kid in the 1960’s in Minnesota I’d talk from Minnesota to New York and such on aurora. They visually shimmer and as they do so, they do the same thing to radio signals and give a Donald duck sound to the voices. Geomagnetic storms cause aurora, coronal holes and flares on the sun cause geomagnetic storms. The K index is the rate of change in the geomagnetic field over a 3 hour period. Right now the K index is 3, the solar wind is 466.4 with a southerly magnetic orientation of -4. All elevated, it’ll be worse tomorrow making better chances for aurora.
Yes, understandable, kinda. You might also look at http://www.solarham.net who runs a nice website. Basically, solar activity runs on an 11 year cycle and we are at the very very bottom of a deep solar minimum. Sun spots create good conditions on lower frequencies, i.e. 7-28 MHz but also leads to flares which leads to geomagnetic disruptions. Basically, sun spots cause an ionization of the reflective layers of the atmosphere which leads to good radio propagation at HF frequencies (3.5 Mhz to 30 MHz). 30-300 MHz are the VHF bands and 300-3000 MHz is UHF. World wide radio communications takes place at HF frequencies.
The ‘disruptions’ we are now seeing result from coronal holes which result in elevated levels of solar wind which distorts and disrupts the earth’s magnetic field. This will cause noise and disruption at lower HF frequencies, but also aurora and fun radio conditions at VHF. Its been a while since we have seen any sunspots at all.
Interestingly, the magnetic polarity of sun spots reverse with each solar cycle. You will see some reference to old cycle spots (cycle 24) versus new cycle spots (cycle 25). Predictions are that the next cycle will be lackluster.
I worked as a geophysicist for a while recording the earth’s magnetic field (amongst other things), and colleagues ran an ionosonde. We were also dependent on HF radio communications, so I understand the basics Just never heard of a “Radio Aurora” (in the ham sense) before. Thanks for your help.
I saw some cluster spots for Es on 50 MHz over the weekend but nothing heard here. Maybe some Au tonight? I have been focused on 80 meters lately as i need 13 countries on 80 to wrap up a five band dxcc.
Hi, Tomorrow 27/08/19 at 20:00 UK time we are trying to have some local contacts on 80m you could try to have listen & see if you can hear us or we can hear you, I will post more info later.
FB Teal, I will listen, but cannot (legally) transmit there. I have one of the antique “advanced” licenses and my band bottom is 3700 for phone. But I will listen. I have England on FT8 on 80 already anyway so it wont help me with the 5 Band DXCC.
Decided to ask the oracle - the guy who wrote the original radio aurora alert/pop-up scripts - and he referred me to this old paper. The distinction between aurora and radio-aurora is explained on the first couple of pages:
“As a working definition, let us now consider aurora to be the sporadic
electromagnetic radiation that is emitted from the atmosphere and
induced by extra-atmospheric atomic or subatomic particles. By
definition the aurora does not include the radio-aurora; they are separate
phenomena with the same basic origin. Aurora is basically emitted
radiation; radio-aurora is basically ionization that reflects radiation.”
ha amused by that quote …the oracle ive never been categorized as that before thought it was some term based on info from a heavenly inspired god like prediction from jason and the argonauts or the old 1980s bbc tv ceefax teletext alternative …
Just never heard of a “Radio Aurora” (in the ham sense) before. Thanks for your help.