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The K7RA Solar Update

07/08/2017

At 0057 UTC on July 7, the Australian Space Forecast Centre issued a Geomagnetic Disturbance Warning: “Expect an increase in geomagnetic activity late on UT day, 08-09 July due to influence of geoeffective coronal hole.”

Our Sun showed no sunspots on July 3-4, so average daily sunspot numbers dropped from 20.3 on June 22-28 to 8 during the current reporting week, June 29 through July 5. Average daily solar flux went from 73.6 to 71.7.

Average daily planetary A index went from 6.9 to 7.1 and average mid-latitude A index went from 7.4 to 8.3, barely any change.

Predicted solar flux is 76 on July 7, 78 on July 8-13, 75 on July 14, 71 on July 15, 72 on July 16-19, 71 on July 20-27, 70 on July 28 through August 2, 71 on August 3-11, 72 on August 12-15 and 71 on August 16-20.

Predicted planetary A index is 5 on July 7, then 8, 25, 18 and 12 on July 8-11, then 8, 5, 13 and 11 on July 12-15, 5 on July 16-20, 11 on July 21-22, 5 on July 23-31, 7 on August 1-2, 5 on August 3-8, then 23, 13 and 11 on August 9-11, 5 on August 12-16, 11 on August 17-18 and 5 on August 19-20.

F.K. Janda, OK1HH of the Czech Propagation Interest Group sent this geomagnetic activity forecast for the period July 7-August 3, 2017.

“Geomagnetic field will be:
Quiet on July 11, 18, 25-26, August 1
Mostly quiet on July 7, 17, 19-21, 24, 29-31
Quiet to unsettled July 9-10, 16, August 2-3
Quiet to active on July 8, 12-13, 15, 22-23, 27
Active to disturbed on July 14, 28

Amplifications of the solar wind from coronal holes are expected on July (8,) 9-12, 14-17, (18, 21,) 22-24, (25,) 30-31.

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


Max White, M0VNG, of Worcester, England sent this very interesting space weather audio dispatch from the UK Met Office: http://www.metoffice.gov.uk/learning/mostly-weather/episode11

Check this: https://www.space.com/37330-solar-minimum-coronal-holes-space-junk.html

And finally, Dick Bingham, W7WKR, who lives way off the grid (“1.2 miles up Company Creek Road”) near Stehekin, Washington sent this off-topic but fascinating piece about an ancient computer: http://wapo.st/2sU76Zx. I’ve heard about this artifact before, but never in such detail.


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.

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

Sunspot numbers for June 29 through July 5, 2017 were 12, 11, 11, 11, 0, 0, and 11, with a mean of 8. 10.7 cm flux was 71.8, 71.5, 70.7, 71.2, 71.7, 71.8, and 73, with a mean of 71.7. Estimated planetary A indices were 5, 4, 11, 18, 5, 4, and 3, with a mean of 7.1. Estimated mid-latitude A indices were 6, 4, 14, 20, 7, 5, and 2, with a mean of 8.3.



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