Conditions turned a little more favorable since last week’s bulletin with both solar flux and sunspot numbers up, and geomagnetic indices substantially lower.
Average daily sunspot numbers for the August 11-17 period were 73.9, compared to 52 for the previous seven days. Average daily solar flux went from 87.9 to 89.2. Average daily planetary A index dropped from 14.6 to 6.9, and average mid-latitude A index went from 13.7 to 7.4.
Predicted solar flux for the near term is 85 on August 19, 80 on August 20, 75 on August 21-22, 85 on August 23-24, 90 on August 25-26, 75 on August 27 through September 1, 80 and 85 on September 2-3, and 90 on September 4-14. Solar flux then pulls back to 75 on September 18-28, then recovers to 90 in the first days of October.
Predicted planetary A index is 10, 14, 8 and 6 on August 19-22, 5 on August 23-24, 12 on August 25, 8 on August 26, 5 on August 27-28, then 15, 25 and 18 on August 29-31, 15 on September 1-2, 12 on September 3-4, and 15 on September 5-6.
The predicted planetary A index is 25 on September 26, indicating high geomagnetic activity.
We have a geomagnetic forecast from F.K. Janda, OK1HH.
The geomagnetic field will be,
Quiet on August 22, 27-28, September 10-12
Mostly quiet on August 19, 23, 26, September 9
Quiet to unsettled on August 20, September 1, 13
Quiet to active on August 21, 24-25, 31, September 2-8, 14
Active to disturbed on August 29-30
Increases of solar wind from coronal holes are expected on August (24-25, 29,) 30-31, September 1, (2-5)
Remark: Parenthesis means lower probability of activity enhancement.
Thanks to David Moore for sending this article about the Van Allen belt: http://bit.ly/2bCqHXb
Note that it mentions a big geomagnetic storm last year on March 17, so I thought it would be interesting to see what the numbers looked like: http://bit.ly/2bOuEMu
Those are some big numbers indicating a big disturbance. Note also that the middle column, which is data for Alaska’s College A index, shows that the instruments were offline or there was some kind of problem gathering data in the four days preceding the big numbers. Unsure if this had anything to do with the impending storm, or if they just got lucky and had everything back online by the day of the big event.
Don’t miss the link half way down the right side of the page on the Van Allen article, titled “Chemtrails Not Real, Say Atmospheric Science Experts.” Nothing to do with radio or propagation, but it has some interesting facts about a belief that I regard as popular folklore.
I noticed in yesterday’s ARRL DX bulletin that there are a lot of scheduled island (IOTA) and lighthouse operations coming up this weekend and beyond.
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 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.
Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.
Sunspot numbers for August 11 through 17 were 82, 86, 73, 61, 70, 81, and 64, with a mean of 73.9. 10.7 cm flux was 94.7, 94.8, 90.5, 87.2, 87.6, 86.5, and 82.9, with a mean of 89.2. Estimated planetary A indices were 9, 11, 5, 4, 4, 6, and 9, with a mean of 6.9. Estimated mid-latitude A indices were 8, 11, 5, 4, 4, 8, and 12 with a mean of 7.4.