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The K7RA Solar Update


The average daily sunspot number for the week was down nearly 38 percent to 78.9, compared to last week’s average of 126.9. The average daily solar flux dropped nearly 13 percent, to 121 from 138.9. The seven-day reporting period for these data ran from November 22-28. Sunspot numbers for November 22-28 were 93, 85, 87, 64, 81, 76 and 66, with a mean of 78.9. The 10.7 centimeter flux was 127.7, 126.7, 118, 121.6, 121.8, 117.1 and 114.3, with a mean of 121. The estimated planetary A indices were 2, 7, 13, 4, 5, 4 and 2, with a mean of 5.3. The estimated mid-latitude A indices were 1, 6, 11, 4, 6, 3 and 2, with a mean of 4.7.

The predicted solar flux for the near term is 110 on November 30, 105 on December 1, 100 on December 2-4, 105 and 115 on December 5-6, 120 on December 7, 130 on December 8-11, 135 on December 12-15, 140 on December 16-17, 135 on December 18-19, 130 on December 20-22, 120 on December 23-24, 115 on December 25, 110 on December 26-28, 115 on December 29-30, 120 on December 31, 125 on January 1-2 and rising again to 130 on January 3-7. The current activity and forecast for the next few days is better than predictions we saw earlier in November; from November 5-18, we presented predictions showing the solar flux going below 100 on November 27-December 2.

The predicted planetary A index is 15 and 8 on November 30-December 1, 5 on December 2-6, 10 on December 7-8, then 5 and 8 on December 9-10, 5 on December 11-15, 8 on December 16, and back down to 5 on December 17-31. The new year is expected to begin with slightly unsettled conditions, with a predicted planetary A index at 10 on January 1-4. The following days through January 13 have a predicted A index of 5, except for January 6 and 12, with a predicted planetary A index of 8.

Dick Grubb, W0QM, of Boulder, Colorado, forwarded some information on D-region absorption, which is interesting to look at when there is a Sudden Ionospheric Disturbance (SID) event. He sent this plot showing HF attenuation during the disturbance described by the PT0S operator last week’s Solar Update.

Backing up the URL hierarchy, we come to this directory. From there, we select “2012” then “November,” which brings us here. Select “November 21,” and it takes us here. We can select data from any hour of the day; in this case he used the 1500 UTC hour. Here we see a mind-boggling trove of data. The particular one he sent was the Global Plot from 1533 UTC. There are also north and south pole plots. You can see these minute by minute if you want, stepping forward and back in time. Here is a list of A and K index readings for the third quarter of 2012. Note the high numbers on July 15, 2012. It looks like the highest K index values were at the 0600 and 0900 UTC readings. At 0639 UTC, you can see a big effect. This looks like an interesting tool for examining some of the effects of solar flares.

John Dyckman, WA3KFT, of Aston, Pennsylvania, is on a local 10 meter SSB net that meets daily at 1800-1900 UTC (1-2 PM local time) on 28.435 MHz. On November 26, he and other stations on the net worked WA7DUH in Washington, KD0TBB, WB0Y and KD0QCF in Colorado, N3AAW in Montana and ZS6JPY in South Africa. Ten meters seemed open to the world, and signals were from S7 to 10 dB over S9 for the whole hour. So even with the somewhat depressed solar activity, 10 meters is still alive.

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.




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