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The K7RA Solar Update


Over this past week, four new sunspot groups appeared. Group 1101 was already in place since August 24, and 1102 emerged on August 29. On September 1, two new sunspot groups -- 1103 and 1104 -- appeared, and on September 2, sunspot group 1105 arrived. Through August 26-September 2, the daily sunspot numbers were 23, 11, 11, 25, 28, 27, 51 and 52 and these same eight days saw the relative total size of all the spots (in millionths of a solar hemisphere) at 100, 100, 130, 170, 180, 220, 270 and 180. The average daily sunspot numbers for August 26-September 1 rose more than 17 points to 25.4, when compared to the previous seven day period. Geomagnetic indicators began the week showing unsettled conditions, but they calmed down to quiet levels again.

Now that August is over, we can look at average sunspot numbers for the previous few months. The three month trailing average of daily sunspot numbers ending in August was 23.2. This is up from the previous two periods ending in June and July, but lower than earlier this year. The three month trailing averages of daily sunspot numbers ending in March-August was 25.7, 22.3, 18.9, 16.4, 20.4 and 23.2.

US Navy and NOAA predict solar flux values of 78 for September 3-4, 76 on September 5-10, 8 on September 11 and 80 on September 12-14. The predicted planetary A index for the same period is 5 on September 3-4, 8 on September 5-7 and 5 on September 8-14. Geophysical Institute Prague predicts quiet conditions on September 3-4, unsettled September 5, quiet September 6, quiet to unsettled September 7 and quiet September 8-9.

Robert Wood, W5AJ, of Midland, Texas, wrote: “Are we now two Sun rotations from the famed WW SSB contest weekend? And is that any indication of conditions for that weekend?”

Two solar rotations is about 55 days, which would be Thursday, October 28, just before the CQ World Wide SSB weekend. I don’t think we can project ahead based on current conditions because we’re not seeing any pronounced recurring activity; solar activity is still very low. Two rotations back is Saturday, July 10. Looking back since July 1, we saw sunspot numbers above 40 on July 23-24, August 5-13 and September 1-2. The number 40 is purely arbitrary, of course, but there is no pattern there based on period of solar rotation.

For geomagnetic activity, since July 1 we had planetary A index over 15 on July 27, August 3-4 and August 24-25. The last period is about one solar rotation after July 27, but there wasn’t a period of geomagnetic activity corresponding to early August in early July. In decades past, we’ve seen periods of intense activity that would come around for several solar rotations, but we aren’t currently witnessing any pronounced solar activity.

In an e-mail, Ron Alexander, KD8ID, of Lansing, Michigan wrote: “One of the complaints that fascinates me is ‘the higher bands are not open, or the bands are very poor.’ I have not found this so; there is always a contact to be made during the early morning, day (weekends) or evening on 40 through 10. The key to good propagation, as you know, is the antenna. Amateurs buy top-of-the-line transceivers and don’t put any money into the antenna. Sunspots help a lot, but antenna selection has a lot to do with making contact. Also, power helps, but it does not help you hear someone better. The antenna does and always will. I consistently work VKs and ZLs in the early morning with 200-300 W on 40 phone. I use an antenna at 72 feet that has a 36 foot boom, nine elements, 3 active on 40, 4 active on 20, 17, 15 and 12, and 6 active on 10. They come in loud and strong unless we are having a K index in excess of 4.Of course, not everyone has the luxury of a large beam based on the area they live. The point I am making is, the bands are open, it’s just a matter of having the right thing up in the air to make a go of it. Additionally, one must understand the practice of propagation to know where to go to find contacts. There is a wealth of information out there including SEC/NOAA education on understanding solar cycles, sun spots and solar flux, along with A and K indexes.”

Ah, to have such a nice antenna high in the air! As Ron says, not everyone has the advantage of a large beam, but he is correct that the antenna is all important. Get a nice look at Ron’s antenna and be sure to click on the photo in the upper-right corner for a larger view.

I found a more dramatic view of Ron’s antenna here. On the upper left click, on “Aerial” then select “Bird’s Eye” in the drop-down menu. Ron’s house is the seventh house south of River Ridge Drive, on the east side of Boxwood Lane. Now click on the “+” in the upper left to zoom in and see the antenna clearly. By clicking on E, W or S on the compass rose in the upper left, you can get completely different views of his location. It is a relatively big antenna on a modest sized residential lot.

David Moore sent in an item from the National Science Foundation that mentions lower levels of ultraviolet radiation from the Sun and the effect on the outer atmosphere.

The autumnal equinox is on September 23 this year. This is a great time for HF propagation, and this year we will probably see higher levels of sunspot activity compared to the equinox in 2009. Running comparative studies on W6ELprop between an average sunspot number of 5 and a more optimistic 25 for this year shows improvement from last year’s propagation.

All times, unless otherwise noted, are UTC.



Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.



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