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The K7RA Solar Update

04/07/2017

Sunspot numbers and solar flux made a strong comeback over the past week, March 30 to April 5.

Average daily solar flux was 96.5 (compared to 77.9 the previous seven days, and 71.2 over the week before that, March 16-22).

Average daily sunspot number progressed from 3.4 to 29.7 to 65.9 over the same three weeks.

The latest daily forecast for Planetary A index and solar flux from NOAA and USAF (updated daily at ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ ) shows solar flux at 76 on April 7, 70 April 8-13, 75 on April 14, 78 on April 15-16, 85 on April 17-19, 72 on April 20-23, 88 on April 24-27, 85 on April 28-29, 105 on April 30, then 100, 97, 92, 85, and 80 on May 1-5, 75 on May 6-7, 78 on May 8-9, 75 on May 10-11, 78 on May 12-13, 85 on May 14-16, and 92 on May 17-20.

The same forecast, but for planetary A index, shows 8 on April 7-8, then 5, 8, and 10 April 9-11, 8 on April 12-13, 5 on April 14-16, then 20, 18 and 10 on April 17-19, 5 on April 20-22, then 55, 28, 20, 22, and 28 on April 23-27, then 15, 10, 8, 7 and 6 on April 28 through May 2, 5 on May 3-13, 20, 18, and 10 on May 14-16, 5 from May 17-19, then 55 and 28 on May 20-21.

At this link – http://bit.ly/2o5Ts6g – you’ll find a nice image from a few days back of sunspot AR2644 and 2645. Also check http://bit.ly/2nNpeCC .

F.K. Janda, OK1HH sent us this geomagnetic activity forecast for the period April 7-May 2, 2017.

“Geomagnetic field will be:
Quiet on April 9-10, 14-16, 20, 30
Mostly quiet on April 8, 11, 19, 21, 29, May 2
Quiet to unsettled April 12-13, May 1
Quiet to active on April 7, 22, 24-28
Active to disturbed on April 17-18, 23

Amplifications of the solar wind from coronal holes are expected on April (7-8,) 11-13. (15,) 16-19, 24-27

Remark:
- Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction.”

Thanks to David Moore (long time contributor to this bulletin) for this, on fast magnetic reconnection: http://bit.ly/2nkGwe8

Max White, a British ham, sent this: https://go.nasa.gov/2nqXBiy


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of 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.

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Sunspot numbers for March 30 through April 5, 2017 were 33, 65, 79, 75, 97, 75, and 37, with a mean of 65.9. 10.7 cm flux was 85.9, 90.6, 101, 112, 107.9, 93.8, and 84.6, with a mean of 96.5. Estimated planetary A indices were 23, 28, 16, 8, 4, 20, and 10, with a mean of 15.6. Estimated mid-latitude A indices were 18, 21, 15, 6, 4, 17, and 10, with a mean of 13.

 



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