SB PROP @ ARL $ARLP040
ARLP040 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 40 ARLP040
From Tad Cook, K7RA
Seattle, WA October 6, 2017
To all radio amateurs
SB PROP ARL ARLP040
ARLP040 Propagation de K7RA
Many things fall apart. Over the past week, the 45 day outlook for
solar flux and planetary A index at
ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ has been in a failure
mode (probably at the US Air Force end, based on past experience)
with no new predictions for three days, October 2-4. This is the
longest outage that I recall for this resource.
Thanks to AD0IU, Space Scientist at the Space Weather Prediction
Center for straightening this out.
Two weeks ago my email account (actually at Gmail, although
forwarded from firstname.lastname@example.org) could not successfully pass email to
any addresses in the arrl.org domain, which meant that ARLP038 was
not posted on September 22.
Over the past week (seven days through October 4) average daily
sunspot numbers rose from 27 to 32.6, and average daily solar flux
rose from 84.3 to 87.9, compared to the previous seven days.
Average daily planetary A index changed from 9.9 to 16.3 and average
daily mid-latitude A index (measured at a single magnetometer at
Wallops Island in the state of Virginia) increased from 7.6 to 12.7.
Predicted solar flux is 85, 82, 80 and 78 on October 6-9, then 75 on
October 10-12, 80 on October 13, 72 on October 14-15, 74 on October
16-18, then 78 and 80 on October 19-20, 85 on October 21-28, 86 on
October 29-30, 84 on October 31, 86 on November 1-2, then 84, 81 and
75 on November 3-5, 72 on November 6-11, 74 on November 12-14, 78
and 80 on November 15-16, and 85 on November 17-19.
Predicted planetary A index is 5, 10, 12, 8, 5, 25, 30, 25, 20 and
15 on October 6-15, 8 on October 16-17, 5 on October 18-23, then 35
and 52 on October 24-25, 15 on October 26-27, then 10 and 8 on
October 28-29, 5 on October 30 through November 1, then 8, 12 and 8
on November 2-4, 5 on November 5-6, 25 on November 7-9, 20 and 15 on
November 10-11, 8 on November 12-13, and 5 on November 14-19.
Those predictions from USAF were sent by the Space Weather
Prediction Center at 2122 UTC on October 5, 2017.
Geomagnetic activity forecast for the period October 6 to November
1, 2017 from F. K. Janda, OK1HH of the Czech Propagation Interested
"Geomagnetic field will be:
"Quiet on October 7, 22-23, 30
Mostly quiet on October 6, 17-19, 21, 29
Quiet to unsettled October 10, 15-16, 28, 31, November 1
Quiet to active on October 8, 11, 13-14, 20, 24, 27
Active to disturbed on October 9, 12, 25-26
"Amplifications of the solar wind, mostly from coronal holes, are
expected on October (6,) 11-16, (17-18, 21-22, 24,) 25.
"Remark: - Amplifications of the solar wind prediction is less
reliable at present. - Parenthesis means lower probability of
activity enhancement and/or lower reliability of prediction."
Fascinating story about previously unknown Hisako Koyama, female
Japanese solar observer who helped fill in the long term record of
This link has the best image of Koyama:
She was born in Tokyo in 1916, retired in 1981 and died in 1997.
Check out this resource on receiving antennas (Thanks to ARRL
W3LPL and K9LA discuss propagation for the upcoming contest season
and predictions for the rest of the current sunspot cycle and the
next one too:
Academic paper on the ratio of the number of sunspots to the number
of sunspot groups:
Excellent article from Earth and Space Science News from the
American Geophysical Union on short-term funding priorities vs. the
long-term record keeping needed for understanding solar cycles:
How an upcoming solar probe will approach the Sun closer than any
Not sure, but I think this may be the latest video from Dr. Tamitha
If you would like to make a comment or have a tip for our readers,
email the author at email@example.com.
For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
http://arrl.org/propagation-of-rf-signals. For an explanation of
numbers used in this bulletin, see
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/.
Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.
Sunspot numbers for September 28 through October 4, 2017 were 40,
39, 38, 34, 25, 25, and 27, with a mean of 32.6. 10.7 cm flux was
90.9, 89.7, 89.4, 85.7, 86, 86.4 and 87, with a mean of 87.9.
Estimated planetary A indices were 55, 12, 16, 11, 7, 8, and 5, with
a mean of 16.3. Estimated mid-latitude A indices were 41, 8, 11, 10,
6, 8, and 5, with a mean of 12.7.