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Propagation Forecast Bulletin #40 de K7RA:

from W1AW Bulletin via the ARRL on October 6, 2017
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Propagation Forecast Bulletin #40 de K7RA:

ZCZC AP40
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 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 k7ra@arrl.net) 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 Group.

"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 sunspot cycles:

http://bit.ly/2xNEXqR

This link has the best image of Koyama:

http://bit.ly/2xjGkf0

She was born in Tokyo in 1916, retired in 1981 and died in 1997.

Check out this resource on receiving antennas (Thanks to ARRL Contest Update):

https://www.w8ji.com/receiving.htm

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:

https://www.youtube.com/watch?v=kPydjVi6qLw

Academic paper on the ratio of the number of sunspots to the number of sunspot groups:

http://bit.ly/2hQf6uG

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:

http://bit.ly/2xYoOzb

How an upcoming solar probe will approach the Sun closer than any other spacecraft:

http://bit.ly/2hQnBWk

Not sure, but I think this may be the latest video from Dr. Tamitha Skov:

https://www.youtube.com/watch?v=Eav7fDO3vfc

If you would like to make a comment or have a tip for our readers, email the author at k7ra@arrl.net.

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 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/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

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.
NNNN
/EX

Source: W1AW Bulletin via the ARRL.

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