SB PROP @ ARL $ARLP041
ARLP041 Propagation de K7RA
ZCZC AP41
QST de W1AW
Propagation Forecast Bulletin 41 ARLP041
From Tad Cook, K7RA
Seattle, WA October 8, 2021
To all radio amateurs
SB PROP ARL ARLP041
ARLP041 Propagation de K7RA
Sunspots were visible every day this week, but numbers were lower.
Average daily sunspot numbers declined from 58.4 to 30.7, and
average daily solar flux was down 2.9 points to 86.9.
Geomagnetic activity was a little higher, with average daily
planetary A index going from 7.3 to 8.1, and average daily middle
latitude A index from 6.3 to 6.7.
Friday, October 1 was affected by a solar flare from sunspot group
AR2871, driving the planetary A index to 15. This had a greater
effect at higher latitudes, with Alaska's College A index hitting 30
and 31 on Friday and Saturday. In the middle of the UTC day on
Saturday the College K index hit 7, a high number.
Predicted solar flux is 86 on October 8 and 9, 84 on October 10 to
14, 75 on October 15 to 16, then 80, 85, 88 and 90 on October 17 to
20, 88 on October 21 and 22, 85 on October 23 and 24, then 90, 100,
95 and 90 on October 25 to 28, 88 on October 29 through November 5,
85 and 80 on November 6 and 7, 75 on November 8 to 12, then 80, 85,
88 and 90 on November 13 to 16.
Predicted planetary A index is 8 on October 8 to 10, then 12 and 8
on October 11 and 12, 5 on October 13 to 17, then 10, 12, 10 and 8
on October 18 to 21, 5 on October 22 to 24, 10 on October 25, 5 on
October 26 to 31, 8 on November 1 and 2, 5 on November 3, 8 on
November 4 and 5, 5 on November 6 to 13, then 10, 12, 10 and 8 on
November 14 to 17.
On October 4 Spaceweather.com reported "Solar Cycle 25 continues to
overperform. Sunspot counts for Sept. 2021 were the highest in
more than 5 years. And, for the 11th month in a row, the sunspot
number has significantly exceeded the official forecast." They
provided this link to that forecast:
https://www.swpc.noaa.gov/news/solar-cycle-25-forecast-update
They continued, "Higher than expected sunspot counts suggest a
stronger cycle, with a peak occurring in late 2024 instead of
mid-2025."
You can read it yourself via the site's archive feature.
Geomagnetic activity forecast for the period October 8 til November
2, 2021 from F. K. Janda, OK1HH.
"Geomagnetic field will be
Quiet on October 16 and 17
Quiet to unsettled on October 8 and 9, 11 to 13, 20 to 22, 24, 26
and 27, 30 and 31
Quiet to active on October 10, 15, 23, 25, November 2
Unsettled to active on October 14, (18 and 19, 28 and 29,) November 1
Active to disturbed, Nothing predicted
Solar wind will intensify on October 11, (19, 22, 25,) 28
Remarks:
- Parenthesis means lower probability of activity enhancement."
After 0000 UTC on October 5, I (K7RA) was calling CQ using FT8 on 12
meters, and noted on pskreporter.info that only two stations outside
my local (CN88uq) Seattle area were receiving me, W2PKY (EL88vi) and
KZ4RB (EL99ic) in Florida, both over 2,500 miles away. W2PKY noted
in an email that 12 meters is a strange band, and reports such as
this are quite common. He also noted that on Wednesday, October 6,
"10 meters was really rockin'.".
I notice frequently that 12 meters has propagation for me across
North America when 10 meters does not. This will change with more
sunspot activity.
NN4X reported last Friday, October 1 from EL98jh in Florida:
"BTW, there were some good LP AND SP openings on 12m to Asia
yesterday. I worked HS3PJF at 1415 UTC and YB2HND at 1425 UTC via
SHORT PATH, over the North Pole. I also worked BA5CW at 1307 UTC,
beaming LP. Thursday evening, I worked RW0LT on 12m at 0022 UTC.
So, we're getting there."
K9LA noted in a recent email, "Events in the lower atmosphere
coupling up to the ionosphere are another factor that can screw up
(or enhance) the bands, not just geomagnetic field activity. With
no parameters to define these lower atmospheric events, we're really
running blind in the short-term. And this is why our propagation
predictions programs are not daily models."
Tamitha Skov, WX6SWW has a three-hour course, "The Ionospheric
Weather Ballet, Part 1."
https://youtu.be/SoXXEIetg4k
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service at http://arrl.org/propagation-of-rf-signals. For an
explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for September 30 through October 6, 2021 were 46,
28, 25, 38, 29, 27, and 22, with a mean of 30.7. 10.7 cm flux was
94.6, 90.5, 87, 86, 83.5, 81.7, and 84.8, with a mean of 86.9.
Estimated planetary A indices were 9, 15, 8, 6, 6, 5, and 8, with a
mean of 8.1. Middle latitude A index was 6, 13, 6, 6, 4, 6, and 6,
with a mean of 6.7.
NNNN
/EX
