Auroral Es and Sporadic E Skip.

[hamateur 1953]

I believe most understand how Auroral E Skip develops after a geomagnetic event.  However, as an old-timer I have heard and read numerous theories over the years, but nothing  that would make any sense to me on why we have such a radical seasonal difference on this phenomenon. Anyone Hams or not wanna weigh in on this?  Meteoric iron dust field alignment is one of more interesting theories I’ve read about btw. 73 Mike N7ORL 

[Drax Spacex]

Auroras are more prevalent around the equinoxes due to more favorable orientation of the Earth's magnetic dipole relative to the Sun / IMF (Equinoctial hypothesis / RMP theory):

https://community.spaceweatherlive.com/topic/2057-are-impacts-stronger-in-summer

Edited February 12, 2023 by Drax Spacex
edit link

[hamateur 1953]

Yup indeed.  The ionization supplied by them is responsible for auroral Es 

During our summer solstice in the northern hemisphere. We experience periodic cases on our six meter band where ionization is so intense that you might feel like someone rolled out a layer of aluminium foil at sixty miles up. I have seen it so intense in one case, a ham I know worked arizona from washington state on sideband two meter band! This is quite rare. Solar flux was under 100 even! Im guessing our amateur community is still clueless on this issue   Part of what makes investigating the unknown so much fun.   Lots of stuff to think about!  73   Mike  

 

[helios]

Aurora and sporadic-E are two distinctive propagation modes though,

Aurora propagation is scatter on actual aurora. Signals experience strong doppler spread, making it often difficult to use for voice.
Examples:
CW (morse): https://youtu.be/T80GMIhJNag?t=106
SSB (voice): https://youtu.be/Fv5taYjXLf8?t=21

Sporadic-E on the other hand is a reflection (refraction) on the E-layer that often occurs independently from geomagnetic storms and also occurs at low/mid latitudes. It does not experience significant doppler spread and can be easily identified on ionograms as being a reflective layer at low altitude (~90 to 110km) with high electron density:


There seems to be a lot of uncertainty about the origin of sporadic-E though. As far as I know, the best candidates are meteor dust and meteorological phenomena at high altitude. But 🤷‍♂️

Edited February 13, 2023 by helios

[hamateur 1953]

Exactly.  auroral Es which I have personally observed and worked at I am was NOT accompanied by any distortion phase shift or any selective fade! I was on amplitude ( ancient) modulation at this time even.  Only  very slight fading was present.  The other two hams were in a local QSO ( conversation) at the time.  The opening was about fifteen minutes long then gone!!  I was floored and so were they!!  This opening was AFTER a geomagnetic storm incidentally as can happen on occasion as above noted 

Love that you included the ionosounding btw!  Great propagation tool. 

Edited February 13, 2023 by hamateur 1953
clarity

[Newbie]

On 2/13/2023 at 1:17 PM, hamateur 1953 said:

Exactly.  auroral Es which I have personally observed and worked at I am was NOT accompanied by any distortion phase shift or any selective fade! I was on amplitude ( ancient) modulation at this time even.  Only  very slight fading was present.  The other two hams were in a local QSO ( conversation) at the time.  The opening was about fifteen minutes long then gone!!  I was floored and so were they!!  This opening was AFTER a geomagnetic storm incidentally as can happen on occasion as above noted 

Love that you included the ionosounding btw!  Great propagation tool. 

The heavens never cease to surprise!!

N.

[hamateur 1953]

note: to all. Im presently unable to credit anyones answer. please don’t post here til it gets resolved. tnx Hamateur 

Edited February 27, 2023 by hamateur 1953

[helios]

This evening I was hearing a british FM station (98.8 MHz) here in Switzerland, about 1200 km distance.
And fair enough, the 6m band is still wide open.
The ionogram in Dourbes (Belgium) shows strong Sporadic-E at 102 km altitude. I think it's the strongest event this year so far.
https://digisonde.oma.be/ionogif/latest.html

[hamateur 1953]

@helios Made a very good observation here! Note the very high MUF. Indicating intense ionosation. 
Sporadic E skip also seems to occur at different times of the day ( at least here in the states.) With one peak around local noon and another near sunset.  Upper level winds might be the cause of this.   On auroral Es there are two ways of using the aurora.  One is to aim your beam antenna at the auroral curtain and try to copy the CW being received . This is difficult at best.  The signals sound raspy and spread as he noted earlier.  If you are patient, wait about a half hour to an hour after the aurora subsides.  If you are lucky residual ionisation will remain, and 50 mhz will open north. 73 Mike. N7ORL . Edit. For users of our very popular digital mode called FT-8 I would imagine if CW and Voice modes are useable most certainly decodes would be a cinch.  

On 5/26/2023 at 12:23 PM, helios said:

This evening I was hearing a british FM station (98.8 MHz) here in Switzerland, about 1200 km distance.
And fair enough, the 6m band is still wide open.
The ionogram in Dourbes (Belgium) shows strong Sporadic-E at 102 km altitude. I think it's the strongest event this year so far.
https://digisonde.oma.be/ionogif/latest.html

 

Edited November 28, 2023 by hamateur 1953