Subj : Solar Activity Significantly Affecting Ionosphere, FCC Opens Docket for Comments on Impact
To   : QST
From : ARRL de WD1CKS
Date : Thu May 30 2024 04:25 pm

05/30/2024

Aurora Propagation, Northern Lights





The sun has been busy, and it's been a mixed bag for radio amateurs. Earlier
this month, millions of people got a chance to see the aurora borealis for the
first time, as the northern lights were active farther south than they had been
in decades. The brilliant displays, visible as far south as Mexico, were a
result of a series of coronal mass ejections. The energy from our star
interacted with particles in the upper atmosphere, causing them to glow in
dancing curtains of multicolored light.

VHF aurora activity was up significantly, according to DX spotting clusters and
activity heard on the air. The 2- and 6-meter bands were especially active, as
the aurora acted like a reflector in the sky to enable signals to propagate
much farther than they normally can on those bands.

G5 Storm Significantly Impacted Ionosphere





ARRL Central Division Director Carl Luetzelschwab, K9LA, is a leading expert on
propagation. He's provided the following analysis of the situation:

May 10, 11, and 12 of 2024 may go down as one of the greatest space weather
storm periods of our lifetimes. It all started with two big sunspots in early
May. These two big sunspots were identified as AR3663 (in the northern solar
hemisphere) and AR3664 (in the southern solar hemisphere). AR stands for Active
Region.

Both of these sunspot regions produced multiple M-class and X-class solar
flares, which caused radio blackouts (signals were significantly attenuated) on
the sunlit side of Earth. Typically, a radio blackout lasts for an hour or so,
is most severe on the lower frequencies, and is due to the x-ray radiation from
the solar flare increasing D-region absorption.

Not only did the big solar flares cause radio blackouts, they also caused solar
radiation storms due to energetic protons that increased ionospheric absorption
in the D region in the polar caps (the area inside the auroral ovals). Solar
radiation storms can last for a couple of days and can result in degraded
propagation on over-the-pole paths.

But the biggest impact to propagation started on May 8, when AR3664 released
multiple Earth-directed CMEs (coronal mass ejections). CMEs manifest themselves
as geomagnetic storms by significantly increasing the 3-hour K index. The K
index indicates the activity of the Earth's magnetic field and ranges from 0
(quiet) to 9 (extremely disturbed). The image (from https://www.swpc.noaa.gov/)
shows the [data from May 10 - 12]. When the K index is this high for such a
long time, the electron density in the F2 region of the ionosphere can be
significantly depleted for days, not allowing higher frequencies to be
propagated. On-the-air activity confirmed this.

In summary, early May was a very interesting period. We saw all three
categories of disturbances to propagation - radio blackouts (x-ray radiation
from solar flares), solar radiation storms (energetic protons from solar
flares), and geomagnetic storms (elevated K indices).

FCC Opens Comments About CME Comms Impacts





The Federal Communications Commission's Public Safety and Homeland Security
Bureau wants to know if you noticed any impacts to radio communications during
the storm. In a public notice, the FCC wrote:

To better understand the impacts of the geomagnetic storm on the U.S.
communications sector, the Bureau is requesting information from communications
service providers and the public regarding disruptions in communications
between May 7 and 11, 2024, that it believes to be a result of the storm. The
Bureau is encouraging commenters to provide any available evidence,
particularly electromagnetic spectrum analyses, imagery, or chronological logs
relating the storm's impacts. Where possible, the Bureau asks that commenters
include the description of the impacts; make and model of affected
communications equipment, which could include transmitters, receivers,
transceivers, switches, routers, amplifiers etc.; make, model, and type of
affected antennae and their composition; frequencies affected; type and
composition of cable adjoining communications equipment and the antennae, if
applicable; duration of the impact; and any residual effects observed in the
hours following restoration.





The public notice is at this link[1] (PDF). Comments may be submitted using the
FCC's Electronic Comment Filing System (ECFS) at https://www.fcc.gov/ecfs[2]
and referring to PS Docket No. 24-161. ARRL's guide to filing comments is at
this link: https://www.arrl.org/arrl-guide-to-filing-comments-with-fcc[3]


[1] https://www.arrl.org/files/file/News/ARRL%20Letter/2024/05-30/24161.pdf
[2] https://www.fcc.gov/ecfs
[3] https://www.arrl.org/arrl-guide-to-filing-comments-with-fcc

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