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Author Topic: Propagation  (Read 664 times)


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« on: June 29, 2012, 2331 UTC »
SB PROP @ ARL $ARLP026 ARLP026 Propagation de K7RA

ZCZC AP27 QST de W1AW Propagation Forecast Bulletin 26 ARLP026 From Tad Cook, K7RA Seattle, WA June 29, 2012 To all radio amateurs SB PROP ARL ARLP026 ARLP026 Propagation de K7RA

Sunspot activity continued to drop until early this week. Average daily sunspot numbers were 26.3, down over 58 points from last week's numbers. Average daily solar flux declined to 92.8, down over 33 points from last week's average.

The weekly sunspot number average has declined since the May 31 through June 6 period, when it was 130.4, followed by 116.1 the next week, 84.6 the next and 26.3 this week.

In next week's bulletin we will have the latest 3-month moving average of daily sunspot numbers, for April-May-June, and it looks like it will be higher than the previous 3-month average, March-April-May. Also, yesterday was day number 180 for 2012, and sunspot numbers are running higher this year. The average sunspot number over those 180 days is 82.4. Previous years 2003-2011 had yearly sunspot number averages of 109.2, 68.6, 48.9, 26.1, 12.8, 4.7, 5.1, 25.5 and 29.9, so 82.4 is quite a jump.

In last week's bulletin ARLP025, we reported the average daily sunspot number as 87, but it was really 84.6. This is because we reported what may have been a preliminary sunspot number of 46 for June 20, but the sunspot number for that date was 29, recorded at http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt.

Geomagnetic conditions over the past week were quiet. Average planetary A index was 5.7, down from 12.6 last week, 9 the week before, and 13.4 before that. The quiet A index for this week was exactly as it was on the week of May 24-30, 5.7.

The latest prediction from USAF/NOAA is from June 28, and it differs very little from the June 27 forecast used in this week's ARRL Letter. It shows geomagnetic activity peaking on June 30 through July 3, probably from a coronal hole spewing solar wind. There is also a thirty-percent chance of M-class solar flares today.

Predicted planetary A index for June 29-30 is 10 and 18, followed by 15 on July 1-3, 8 on July 4, 5 on July 5-7, 8 on July 8-9, and 5 on July 10-25, and then on July 26-31, 10, 18, 15, 15, 15 and 8. This is an echo of the activity this week, based on the 27.5 day rotation of our Sun relative to Earth.

The predicted solar flux is 115 on June 29-30, 120 and 125 on July 1-2, 130 on July 3-5, 135 and 140 on July 6-7, 135 on July 8-9, 130 on July 10-11, 125 on July 12-13, then 120, 115, 110 and 105 on July 14-17. Solar flux may dip below 100 around July 19 and rise above 100 after July 28. But that is a long way out, and difficult to predict.

OK1MGW of the Czech Propagation Interest Group predicts quiet to unsettled geomagnetic conditions on June 29, quiet to active June 30, active July 1-3, quiet to unsettled July 4-7, quiet to active July 8-9, and mostly quiet on July 10-12.

Scott Woelm, WX0V of Fridley, Minnesota commented on the recent lack of sunspots, and may have discovered a correlation of some sort. He wrote, "I have found the reason for the recent decline in sunspots! My Dad, David Woelm, W0ELM, just got a new radio." Good thinking! He also wrote, "For those interested, I have some images of the recent Annular Eclipse in May, and the Venus Transit in June, on my web site:



The second link has a great shot of the Annular Eclipse that was taken in Texas by Bob Adams, KC0JJ, of Crystal, Minnesota."

Conditions were pretty good for 2012 Field Day last weekend, meaning there was some solar activity, and geomagnetic conditions were nice and quiet. Some past Field Days didn't have it so good.

At http://wdc.kugi.kyoto-u.ac.jp/kp/index.html you can download planetary K and A indices all the way back to 1932, and with a perpetual calendar you can find the fourth full weekend in June for any year. 1988 ARRL Field Day on June 25-26 looks particularly bad, and so does June 23-24, 1984. Either may have been the year I was out with the Western Washington DX Club, and a sudden ionospheric disturbance hit late Saturday morning, making all receivers appear dead. You can see by downloading the data for 1988 that the K index hit 4 and 5 on Saturday morning, then conditions recovered into the evening, only to have a repeat on Sunday morning, a double-whammy.

Bill Mader, K8TE, president of the Albuquerque DX Association sent a report on the W5UR Field Day operation at Torrance County Park in Edgewood, New Mexico:

"Conditions were generally very good for FD excluding 6 and 10 meters. Our 10 meter CW station made just one contact and 6 meters made just 48 contacts with the majority during an opening to California Saturday evening. Propagation for both was disappointing compared with previous years."

"15 and 20 made up the bulk of the SSB and three CW stations QSOs and were hot! We


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