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47292
From: Eve, [DNS_Address]
Subject: POLAR CAP ABSORPTION EVENT IN PROGRESS
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POLAR CAP ABSORPTION EVENT IN PROGRESS: Don't try to use a shortwave radio inside the Arctic Circle this week. It might not work. A deep polar cap absorption (PCA) event is in progress:  Red zones in this global map show where shortwave transmissions are being absorbed. Frequencies below 15 MHz are almost completely blacked out, while anything below 35 MHz is being attentuated, at least a little. What's causing this? Protons accelerated by Monday's extremely rare CME are still hitting our planet 3 days later. Earth's magnetic field funnels these particles toward the poles where their ionizing effect causes the absorption of shortwave radio. The PCA is intensifying; you can can monitor its progress here. https://spaceweather.com/ -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------  Polar Cap Absorption Events - Massive Short Wave Communications Blackouts The Trigger: The Arrival of a Solar Proton Event Occasionally the Sun blows clouds of very high velocity protons at the Earth (called a solar proton event). Solar protons can penetrate into the Earth's magnetosphere near the magnetic poles. Solar protons with energies up to about 10 million electron volts bombard the ionosphere, knocking electrons free during collisions with air particles and increasing the density of the ionosphere at low altitudes (in the D- and E-regions). The Effects on Radio Waves Short wave radio waves at relatively high frequencies (in the HF range) are absorbed by the increased particles in the low altitude ionosphere causing a complete black out of radio communications. This is called a Polar Cap Absorption (PCA) event. Lower frequency waves that would normally reflect off the low altitude ( D- or E-region) ionospheric layers now do so at lower than normal altitudes changing dramatically their propagation paths. How Long Does a PCA Last? PCA events are particularly devastating to radio communications because they can last for days depending on the size and location of the magnetic disturbance on the Sun that produces them. https://www.windows2universe.org/spaceweather/polar_com.html ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ real time proton levels on earth graph: https://www.swpc.noaa.gov/products/goes-proton-flux |
47294
From: Eve, [DNS_Address]
Subject: Re: POLAR CAP ABSORPTION EVENT IN PROGRESS (subsiding)
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POLAR RADIO BLACKOUT IS SUBSIDING: Inside the Arctic Circle, shortwave radios are working again as a three-day blackout triggered by Monday's extremely rare CME subsides. The blackout is called a "polar cap absorption event" or PCA. It was caused by energetic protons accelerated toward Earth by the CME. Those protons are now ebbing, so the normal propagation of shortwave radio signals can resume. spaceweather.com |
47295
From: pamela, [DNS_Address]
Subject: Re: POLAR CAP ABSORPTION EVENT IN PROGRESS (subsiding)
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btw, thanks Evie for following all of these reports, I've been following them also. |
Responses:
[47296]
47296
From: Evie, [DNS_Address]
Subject: Re: POLAR CAP ABSORPTION EVENT IN PROGRESS (subsiding)
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:0) ~⭐️...~..🙂..~..-...⭐️~ |
Responses:
None
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