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The K7RA Solar Update


Australia’s Space Weather Services issued a geomagnetic warning at 0022 UTC on September 29.

“The geomagnetic conditions are expected to vary between active levels to major storms for the next three days. This is because the solar winds are expected to be in excess of 600 km/s associated with a very large positive polarity coronal hole. The storm intensities are expected to be slightly stronger than that observed in the previous two solar rotations (previous rotation Ap was 32) associated with this coronal hole because the earth-sun coupling efficiency is highest during the equinox periods. Thus there is chance that aurora may be visible on the local nights of 29 September from Tasmania and some parts of Victoria, Australia.



29 Sep:  Minor Storm

30 Sep:  Minor Storm

01 Oct:  Active to Minor Storm"


This week’s (September 22-28) average daily sunspot numbers and solar flux changed little from the previous seven days. Average daily sunspot numbers changed from 29.9 to 29.7, and average daily solar flux declined just two points from 83.4 to 81.4. Average planetary A index was much higher, changing from 8.9 to 19.7, and average mid-latitude A index changed from 7.6 to 12.3.

Projected solar flux for the near term is 81 and 78 on September 30 through October 1, 80 on October 2-3, 82 and 85 on October 4-5, 90 on October 6-14, 95 on October 15-18, 90 on October 19-21, 85 on October 22-27, 80 on October 28-31, 85 on November 1-3, and 90 on November 4-10.

Predicted planetary A index is 38, 30, 20, 14, 12, 10 and 6 on September 30 through October 6, 5 on October 7-14, then 8, 10, 20, 10, on October 15-18, 5 on October 19-22, then 18 and 12 on October 23-24, 35 on October 25-27, then 25, 20, 16, 10 and 8 on October 28 through November 1, 5 on November 2-10, and 8 on November 11.


Here is the weekly geomagnetic forecast from F.K. Janda, OK1HH of the Czech Propagation Interest Group.

“Geomagnetic activity forecast for the period September 30-October 26, 2016

Geomagnetic field will be:

Quiet on October 9-10, 13,

Mostly quiet on October 7, 11, 14, 20,

Quiet to unsettled on October 5-6, 8, 15-16, 19, 21,

Quiet to active on October 1-3, 5, 12, 17-18, 23-24

Active to disturbed on September 30, October 4, 22, 25-26

Increases of solar wind from coronal holes are expected on September 30, October 1-3 and 15-17.”


On September 24 Jim McLelland, WA6QBU, of Santa Rosa, California sent this: “Just a quick note about DX. I noted last night that conditions were quiet on 20 meters, which is unusual for me on the West Coast, with sunspots at 30, SFU at 85 and a quiet sun. Therefore, moving to 40 meters, I found the band open to South Africa and worked Bill, ZS6CCY, who was 10 dB over S9. Keep up the good work.”

Then on September 30 he wrote, “Mr. Cook, one more thing: 10 meters was open to Hawaii (SSB) from the West Coast last weekend and again Tuesday early evening.”

Mark Ammann, KM0A, had some comments about VHF propagation enhanced by aurora in a September 28 e-mail: “I always enjoy reading your propagation updates via ARRL e-mail member list, and especially the personalized experiences you include. Having been on 2 meters and 6 meters for almost 40 years, aurora is always fascinating yet rare, more so on 2 meters since it provides DX distances normally unattainable on that band, save for extended tropo or the rare E-skip opening. I wanted to add to your comments re Jon, N0JK’s, aurora during the 2 Meter Sprint contest.

Two-meter aurora CW signals, in my opinion, are not ‘buzzy’ or ‘distorted,’ but actually very easy to copy unless the signals are extremely weak. They sound more like a hollow whisper.

“As for aurora on 6 meter SSB, signals are distorted somewhat but easy to copy if one speaks slowly. As for 2 meter SSB, signals are much distorted and very difficult to comprehend. Sounds almost like the person is gargling rocks!

Keep up the good work!"


Mark included links with audio samples of CW and SSB signals received via auroral propagation.


Ted Leaf, K6HI, of Kona, Hawaii sent this about using NVIS—Near Vertical Incident Skywave—antennas on 40 meters: “We have nets across the Hawaiian Island chain at 4 PM (0200 UTC) on 40 meters with our low antennas barefoot. Conditions can sometimes be noisy, but we usually work all stations.”

Here are some NVIS references:


Jon Jones, N0JK, of Lawrence, Kansas sent this report early Friday morning, September 30:

"With the fall equinox and geomagnetic storms this week due to a fast moving stream of solar wind, 10 meters has come alive on north - south paths. The last couple of days Uli, VP6AH has had a loud signal on 10 meters to North America. He is running just 100 watts and a dipole antenna and was over S-9 on my mobile Sept. 27 ~ 2015z. H44GC, VK9NZ, FY5KE, VP8LP and others have also been active on 10."


And finally, a story about a geomagnetic disturbance in 1941. Thanks to Rick Lindquist, WW1ME, who forwarded this from the Southgate Amateur Radio News:


For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve overseas locations are at

Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for September 22 through 28 were 30, 49, 47, 18, 23, 21, and 20, with a mean of 29.7. 10.7 cm flux was 85.1, 85.5, 84.9, 84.6, 86.8, 85.6, and 84.4, with a mean of 81.4. Estimated planetary A indices were 4, 4, 5, 23, 22, 38, and 42, with a mean of 19.7. Estimated mid-latitude A indices were 4, 3, 4, 12, 18, 21, and 24, with a mean of 12.3.