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Propagation Forecast Bulletin
From Tad Cook, K7RA
We may be in another period of zero sunspots. From October 24-28
there was a sunspot count of 0 on each day. Three days at the beginning
of the month were no-sunspot days, and four months ago there were
five days (July 18-22) with no spots. A year from now expect to
see longer periods of 0 sunspot readings, possibly up to several
weeks, based on what the periods between previous sunspot cycles
were like.
Earlier this month Propagation Forecast Bulletin ARLP042 (October
6) referred to a nomograph, a graphic representation of numerical
relations, like a ruler calibrated with inches and centimeters.
This nomograph was supposed to illustrate the relationship between
A index and K index, such as the figures seen in the table at, http://www.sec.noaa.gov/ftpdir/indices/DGD.txt.
Unfortunately, the bulletin just quoted that same URL twice, but
the unmentioned URL (the one with the nomograph) can be found at,
http://www.ngdc.noaa.gov/stp/GEOMAG/kp_ap.html.
Geomagnetic conditions should be fairly active for Friday. The
predicted planetary A index for Friday through Monday, November
11-14 is 15, 8, 5 and 5. The Prague Geophysical Institute predicts
unsettled to active conditions on November 11 and 12, unsettled
conditions on November 13, quiet to unsettled on November 14 and
15, and quiet conditions November 16-17.
Remember that for good HF propagation we want these geomagnetic
numbers to be low, with sunspot numbers as high as possible.
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 and an explanation
of the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at,
http://www.arrl.org/tis/info/propagation.html.
An archive of past bulletins is found at, http://www.arrl.org/w1aw/prop/.
Sunspot numbers for November 3 through 9 were 24, 22, 18, 34, 31,
38 and 13 with a mean of 25.7. 10.7 cm flux was 76.8, 77.4, 79.3,
81.7, 79.4, 79.4, and 78.1, with a mean of 78.9. Estimated planetary
A indices were 24, 20, 10, 10, 6, 3 and 3 with a mean of 10.9. Estimated
mid-latitude A indices were 19, 16, 10, 12, 6, 2 and 1, with a mean
of 9.4.
Source: ARRL Letter - courtesy of The
American Radio Relay League
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