25 MHz WWV propagation

[David G. McGaw]

I am wondering if anyone can explain what I have been observing of
propagation as it relates to 25 MHz WWV.

It has been coming in here in NH starting late morning and can stay
through the evening.  As of late, this has not been the case.

Propagation has a whole been quite poor ever since the May 10
geomagnetic storm, but in particular while 20 MHz WWV has generally been
good during the day, 25 MHz has been missing.  The KC2G MUF plots seem
to support this, except last night just after Midnight Local (Eastern),
it actually started coming in.  This morning, it was bombing in S9.  By
Noon it had disappeared again.  The MUF plot however showed no such
propagation.

Of course, right now we have gotten 2 large flares AND presumably a CME,
so all bets are off.  All signals are very weak (14.670 MHz CHU, 15 and
20 MHz WWV) or non-existent!

73,

David N1HAC

[David Eckhardt]

You might check for solar flares.  We've had two major flares just today.  The second about 1830 UT really did a number on the ionosphere.  I continuously monitor using a DC receiver for Doppler scattering of the 25 MHz WWV signal.  I'm only some 25 miles south of Wellington, Colorado, where WWV transmitters are located.  I got a rather drastic SID recorded on that system for that latest solar flare, a Class M-9.6, that lasted a bit in excess of a full hour.  I use the following for confirmation of solar flares:

     https://www.swpc.noaa.gov/ 

Just an unofficial observation:  Since the huge disturbance of last month, the ionosphere has struggles to get back to "normal" as I detect on the 25 MHz Dopplergram of WWV.

Dave - WØLEV

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Dave - WØLEV

[Gary Mikitin, AF8A]

David et al - You might find the recent article by Carl, K9LA to be interesting and relevant to the 25 MHz WWV question:  "Decreased Summer MUFs", which appears on page 23 of the CWops newsletter, Solid Copy.

https://cwops.org/wp-content/uploads/2024/06/Solid-Copy_2024_June_FINAL.pdf

73 de Gary, AF8A

CWops #2092