> The most likely mode of propagation was marine ducting with the signal being trapped close to the ocean.
> There is a whole truckload of Sahara dust getting across the Atlantic this week. I blame it for the modification of the normal atmosphere into a superrefractive one, supporting communications for the first time on this band. Sahara dust dryes the air around it by absorbing moisture and thus modifying the refraction index. Like a G-Line feeder or an optical fiber, the difference in refraction index between different layers allows the propagation path to curve down following the Earth curvature to allow these fantastic QSOs.
> I read about this phenomenon many years ago in an old ITU Bulletin justifying the enhanced superrefraction conditions usual between Cape Verde and the Western African Coast.
> Jose, CO2JA
From you:
> this radio contact was made possible by the recently-developed FT8 digital modulation scheme
My questions:
1. which factor was more important, or were they equal?
2. Is it COVID related? ie, atmospheric conditions are suddenly different around the world due to shutdown of industry.
I've worked parallel to a whole bunch of radio obsessed electronic engineers; they get really excited about atmospheric conditions, and they regularly use weather maps to win competitions with unusually long transmission ranges (- a whole bunch of mad people across England / Europe / etc. go out on the same day and try and make as many contacts as possible. The team with the most unique contacts wins).
1. I don't think you can quantify the two in equal units such that they can be compared - they both played a part.
2. Probably not or at least not significantly. Ducting occurs frequently and Saharan dust is blown out to sea every year. Note that 'for the first time on this band [at this distance]' is more accurate.
> The most likely mode of propagation was marine ducting with the signal being trapped close to the ocean.
> There is a whole truckload of Sahara dust getting across the Atlantic this week. I blame it for the modification of the normal atmosphere into a superrefractive one, supporting communications for the first time on this band. Sahara dust dryes the air around it by absorbing moisture and thus modifying the refraction index. Like a G-Line feeder or an optical fiber, the difference in refraction index between different layers allows the propagation path to curve down following the Earth curvature to allow these fantastic QSOs.
> I read about this phenomenon many years ago in an old ITU Bulletin justifying the enhanced superrefraction conditions usual between Cape Verde and the Western African Coast.
> Jose, CO2JA
From you:
> this radio contact was made possible by the recently-developed FT8 digital modulation scheme
My questions:
1. which factor was more important, or were they equal?
2. Is it COVID related? ie, atmospheric conditions are suddenly different around the world due to shutdown of industry.