10 November, 2012
ARLP045
Again this week solar activity retreated. Average daily
sunspot numbers declined 8.7 points to 49.7, and average daily solar
flux was down nearly 20 points to 97.2.
The latest forecast (from Thursday, November 8) shows
solar flux at 105 and 110 on November 9-10, 115 on November 11-17, 110
on November 18-20, 105 and 100 on November 21-22, 105 on November 23-24,
and 100 on November 25-26. Flux values then drop below 100 on November
27 through December 2.
The planetary A index forecast predicts an A index of 5
on November 9, 7 on November 10-12, 5 on November 13-18, 8 on November
19, 5 on November 20 through December 4, and 10 on December 5-8.
Currently the Sun is peppered with a few weak spots, but
there have been 1-2 new sunspot groups every day starting on November 3.
November 3 had one new spot, November 4 had two, then two
more on November 5, one on November 6 and another on November 7, and
two new ones on November 8.
OK1HH has a new geomagnetic forecast from Prague, and he
predicts quiet to unsettled conditions November 9, active to disturbed
November 10, quiet to active November 11, quiet to unsettled November
12, quiet November 13, mostly quiet November 14-15, quiet again November
16-19, mostly quiet November 20, quiet November 21, mostly quiet
November 22-23, quiet November 24-26, quiet to active November 27,
active to disturbed November 28, quiet to unsettled November 29, and
quiet on December 1.
NASA tweaked their forecast for the smoothed sunspot
number at the peak of Cycle 24 next Fall. On October 2 they predicted a
sunspot number maximum of 75 in Fall 2013, and on November 2 they
changed that to 73.
Scott Wright, K0MD of Rochester, Minnesota shared some
brief observations on conditions during the CQ World Wide DX SSB Contest
(October 27-28, two weekends ago). He wrote, "I did not find the band
openings nearly as good this year as last year. Ten meters was very good
but not as good as 2011. Propagation was down on 40 meters with lower
country totals from the Midwest than I saw last year. 160 was not very
good but no surprise there, given it is October."
Check out Scott's station at http://www.k0md.com/.
The next CQ World Wide DX contest is the CW weekend, November 24-25. See http://www.cqww.com/. A week from now is the Phone weekend for ARRL Sweepstakes, a domestic contest. See
http://www.arrl.org/sweepstakes.
Scott noted the better propagation during the same
contest last year. This year, the average daily sunspot number for the
ten day period ending on Sunday, October 28, the last day of the
contest, was 79.8. But for the same period last year, ending on Sunday,
October 30, 2011 the average daily sunspot number was 111.6, quite a bit
higher, by 40% in fact.
Max White, M0VNG of Worcester, UK sent this article about a coronal hole and a disastrous solar wind back in January 1994:
http://o.canada.com/2012/10/17/canadian-scientists-identify-suns-
coronal-hole-as-culprit-in-1994-anik-satellite-failures/.
We can check an archive of geomagnetic indices to get a sense of what the effect on Earth was:
http://www.swpc.noaa.gov/ftpdir/indices/old_indices/1994_DGD.txt
Note there are days in January of that year when readings
from the magnetometer near Fairbanks, Alaska (the College A index) that
have asterisks instead of numbers. This is what we see occasionally
when the magnetometer is completely overloaded with energy, and cannot
produce any sort of meaningful results.
We can see there was a lot of geomagnetic activity that
year. I would like to refer back to propagation forecast bulletins from
January 1994, but unfortunately the online archive at http://arrl.org/w1aw-bulletins-archive-propagation
doesn't begin until January 1995. If anyone has copies of the
propagation bulletin prior to 1995, please contact me. Perhaps you have
an old hard drive from a personal computer used for packet radio twenty
years ago?
K9LA has some great propagation resources on his web site at
http://myplace.frontier.com/~k9la/index.html.
He has download links for free pdf copies of both NM7M propagation
books, and a slide presentation showing an update on Cycle 24 that he
presented in July. If you don't have Microsoft PowerPoint to watch the
slides, you can download a free reader at http://www.microsoft.com/en-us/download/
details.aspx?id=13.
From two years ago, G0KYA has a downloadable pdf eBook titled "Understanding LF and HF Propagation" at http://g0kya.blogspot.com/
2010/11/understanding-lf-and-hf-propagation.html.
If you would like to make a comment or have a tip for our readers, mail the author at, k7ra@arrl.net.
For more information concerning radio propagation, see the ARRL Technical Information Service at
http://arrl.org/propagation-of-rf-signals.
For an explanation of the numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.
An archive ofpast propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation.
Find more good information and tutorials on propagation at
http://myplace.frontier.com/~k9la/.
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 November 1 through 7 were 48, 34, 35,
46, 47, 61, and 77, with a mean of 49.7. 10.7 cm flux was 98.4, 96.5,
93.3, 95, 96.6, 98.7, and 101.7, with a mean of 97.2. Estimated
planetary A indices were 17, 5, 3, 2, 2, 4, and 10, with a mean of 6.1.
Estimated mid-latitude A indices were 17, 5, 2, 1, 2, 4, and 10, with a
mean of 5.9.
Source: The American Radio Relay League
• All propagation reports can be found at:
http://www.southgatearc.org/propagation
