ARRL

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The K7RA Solar Update

10/11/2013

Solar activity picked up over the seven days of our reporting week, October 3-9, and the outlook has improved somewhat. There now are no predictions for the solar flux dropping below 100 in the next 45 days. October 6 was the date of the last forecast predicting any flux values below 100. These predictions were for periods later in October and again in November.

Average daily sunspot numbers increased by 47 points to 79, and average daily solar flux increased 3.8 points to 110.4. These averages compare the recent October 3-9 period with the previous seven days, September 26 through October 2.

The latest prediction for solar flux is 125 on October 11-13, 120 on October 14-16, 115 on October 17, 105 on October 18-23, 100 on October 24-29, 105 on October 30-31, 100 on November 1-2, 105 on November 3-4, 100 on November 5-6, and 105 on November 7-15.

Predicted planetary A index is 10 on October 11-12, 5 on October 13, 8 on October 14-15, 10 on October 16, 8 on October 17, 5 on October 18-20, 10 on October 21, 5 on October 22 to November 6, 10 on November 7-8, and 8 on November 9-12.

OK1HH predicts geomagnetic activity as quiet to unsettled October 11, mostly quite October 12, quiet October 13, quiet to unsettled October 14-16, quiet to active October 17-18, quiet October 19-20, quiet to active October 21, mostly quiet October 22, quiet October 23-27, quiet to active October 28, and active to disturbed October 29-30.

NBC news has an article about Tuesday’s solar flare, which was strong considering how quiet the sun has been lately, but was not aimed directly at earth. Planetary A index rose to 24 on Wednesday, October 9, and Alaska’s college A index hit 40.

http://www.nbcnews.com/science/strongest-solar-flare-months-unleashed-sun-8C11369482

Tomas Hood, NW7US, who writes propagation columns for CQ, CQ VHF and Popular Communications, sent a video he put together concerning a solar flare mentioned in last week’s bulletin ARLP040.

http://g.nw7us.us/19hP1c3

Silverio, IK3IUL sent an inquiry, but replies to him seem to be bouncing. Perhaps he could try again via another email account.



For more information concerning radio propagation, see the ARRL Technical Information Service at http://www.arrl.org/propagation-of-rf-signals. For an explanation of the numbers used in this bulletin, see http://www.arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://www.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://www.arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://www.arrl.org/bulletins.

Sunspot numbers for October 3 through 9 were 61, 84, 69, 53, 76, 99, and 111, with a mean of 79. 10.7 cm flux was 113.8, 109.1, 105.9, 106.5, 112, 111.9, and 113.4, with a mean of 110.4. Estimated planetary A indices were 6, 2, 1, 2, 6, 16, and 24, with a mean of 8.1. Estimated mid-latitude A indices were 5, 2, 2, 3, 8, 12, and 21, with a mean of 7.6.



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