Subj : The K7RA Solar Update
To   : QST
From : ARRL de WD1CKS
Date : Fri Dec 06 2024 10:38 pm

12/06/2024

Solar activity seems to have dropped dramatically from a recent peak.� Are we
over the cycle peak and headed down again?� Too early to say.

Daily average sunspot numbers this week sank to 120.1.

Predicted solar flux is 175 on December 6 to 8, 170 on December 9 and 10, 175
on December 11 and 12, and 205 on December 13 to 17.

Predicted planetary A index is 8 on December 6 and 7, 5 on December to 12, 10,
8 and 5 on December 13 to 15, 8 on December 16 to 18, 12 and 8 on December 19
and 20 and 5 on December 21 through January 6, 2025.

Commentary from OK1HH:

"After the unexpected solar proton flare of 21 November, which took place
beyond the Sun's western limb, a rain of higher-energy protons hit the Earth's
atmosphere.� This solar radiation storm had a greater impact at higher
latitudes in the southern hemisphere, where it caused a significant increase in
attenuation.

"Two days later, two new large sunspot groups appeared near the southeastern
limb of the Sun.� These produced moderate eruptions daily, which is more or
less normal for the 11-year maximum.� These are AR3905 and AR3906, which have
grown rapidly to a size where they can be observed with the naked eye.� There
is a relatively small coronal hole near them that could be influencing the
solar wind enhancement.

"Following the eruption of a plasma filament near AR3901, a G2 class
geomagnetic storm is possible on November 28 and 29, when a CME is expected to
impact.� However, around 1900 UT on November 28, when this information is
written as usual, nothing is still happening. We will see what happens next.
It is quite possible that the plasma cloud will only hit the Earth a little and
it is also not out of the question that it will miss the Earth completely.� So
any prediction at this point has a low probability of coming true."

Send your tips, reports, observations, questions and comments to
[email protected][1].� When reporting observations, don't forget to tell us which
mode you were operating.

For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation[2] and the ARRL Technical Information Service
web page at, http://arrl.org/propagation-of-rf-signals[3] .

For an explanation of numbers used in this bulletin, see

http://arrl.org/the-sun-the-earth-the-ionosphere[4] .

An archive of past propagation bulletins is at

http://arrl.org/w1aw-bulletins-archive-propagation[5]�

More good information and tutorials are at http://k9la.us/[6].

Also, check "Understanding Solar Indices" from September 2002 QST:
https://bit.ly/3Rc8Njt[7] .

Instructions for starting or ending email subscriptions to ARRL bulletins are
at http://arrl.org/bulletins[8] .

�Sunspot numbers for November 28 through December 4, 2024 were 149, 162, 103,
83, 113, 126, and 105, with a mean of 120.1.� 10.7 cm flux was 213.9, 219.8,
204, 186.3, 185.3, 174.2, and 174.7, with a mean of 202.2.� Estimated planetary
A indices were 4, 8, 11, 7, 6, 13, and 7, with a mean of 8.3.� Middle latitude
A Index was 3, 6, 9, 6, 6, 6, 10, and 5, with a mean of 6.


[1] mailto:[email protected]
[2] http://www.arrl.org/propagation
[3] http://arrl.org/propagation-of-rf-signals
[4] http://arrl.org/the-sun-the-earth-the-ionosphere
[5] http://arrl.org/w1aw-bulletins-archive-propagation
[6] http://k9la.us/
[7] https://bit.ly/3Rc8Njt
[8] http://arrl.org/bulletins

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� Synchronet � Whiskey Lover's Amateur Radio BBS

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