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 Previous: Surfin': Long-Delayed Echoes Again |  Next: Huntsville to Host Global EmComm Conference in August |
The average daily sunspot number for this week rose nearly 18 points from the previous seven days. On July 4, the A index was moderately elevated due to a solar wind stream. Expect to see a similar increase around July 11, and a much greater increase in geomagnetic activity from July 16-19. Geophysical Institute Prague predicts quiet conditions for July 6-9, quiet to unsettled July 10, and unsettled conditions for July 11.
Monthly averages of daily sunspot numbers for April 2006 through June 2007 were 55.2, 39.6, 24.4, 22.6, 22.8, 25.2, 14.7, 31.5, 22.2, 28.2, 17.3, 9.8, 6.9, 19.8 and 20.7. Monthly averages of daily solar flux for the same period were 88.9, 80.9, 76.5, 75.8, 79, 77.8, 74.3, 86.3, 84.4, 83.5, 77.7, 72.2, 72.4, 74.4 and 73.7.
Looking at three-month smoothed sunspot numbers, and knowing the June numbers, we can add them to April and May to show the three-month average centered on May.
Here are the three-month smoothed sunspot numbers based on data from the past 22 months:
Oct 05 28
Nov 05 36
Dec 05 40.6
Jan 06 32.4
Feb 06 18.1
Mar 06 27.7
Apr 06 38.5
May 06 39.7
Jun 06 28.9
Jul 06 23.3
Aug 06 23.5
Sep 06 21.2
Oct 06 24.1
Nov 06 23.1
Dec 06 27.3
Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Why do we say 22 months when only 20 months are shown? This is because these numbers are based on data from September 2005-June 2007. The months shown are the center of each three month average of daily sunspot numbers.
Notice the averages centered on December 2006-May 2007. If we narrowly focus on just these data, it sure looks like the cycle reached a minimum centered on March 2007, rising since then. Note also from the monthly averages above that the June average at 20.7 is nearly five points higher than the three average centered on May.
Look on page 9 in the July 3 Weekly Preliminary Report and Forecast at and note the cycle minimum is shown as March 2007, the same month that our three-month average shows. This table is of actual and predicted smoothed sunspot numbers, each based on a year of data. December 2006 is based entirely on known data, January 2007 is based on known data plus one month of predicted data (July), February is based on two months of predicted data (July and August) and the rest known data, and so on.
More 6 meter and Field Day reports came in this week. Several Field Day stations had a lot of luck on 15 meters, and they tended to be in the Midwest and the South. Dustin Cox, KE5NKG, of New Mexico said that on Field Day he had a great overnight run on 15 meters.
There was a great deal of 6 meter activity in the final week of June. On June 25 John Butrovich, W6UWB, of Orange Grove, Texas (EL17ax) worked 20 European stations, mostly UK, using the weak-signal JT6M mode on 50.257 MHz. For more info on JT6M, see www.qsl.net/wa5ufh/Misc/jt6m.htm.
On June 25, James Kesterson, K0GU, in Wellington, Colorado (DN70mq) worked 18 European 6 meter stations, and a few more the next two days. Mark Bell, K3MSB, of Airville, Pennsylvania worked a number of West Coast 6 meter stations, and on June 27 worked IK2GSO on CW at 2156 UTC. Brian Smith, W9IND, of Indianapolis reported that his club's 6 meter beacon, W9VW, was heard in Scotland, with propagation from EM69 to IO75.
Also in EM69, Melvin Crichton, KJ9C, had great luck on 6 meters late in the afternoon on June 29, working several Europeans on CW. He wonders why more overseas stations don't try 6 meter CW, and notes, "The Caribbean guys seem to be stuck on SSB."
Dick Battle, AK4RB, in FM06 in North Carolina was thrilled to work Dave Robinson, WW2R, in North Texas (EM03) for his first ever 6 meter QSO on June 30. Dick does not have a 6 meter antenna, but used an antenna tuner to load his HF wire doublet hidden in the attic of his townhouse. On June 26 Kevin Blanton, KE5DUK, in Beebe, Arkansas (EM34) worked his first long-distance 6 meter contact using FM simplex on 52.525 MHz and talked to someone in FN06 in Ontario. He also worked New York, Tennessee, North Dakota and Pennsylvania. There were many more 6-meter reports this week, too many to mention here.
Sunspot numbers for June 28 through July 4 were 27, 29, 36, 30, 13, 12 and 13 with a mean of 22.9. 10.7 cm flux was 74.9, 75.3, 74, 74.3, 72.6, 71.7, and 72.4, with a mean of 73.6. Estimated planetary A indices were 6, 13, 6, 5, 3, 9 and 16 with a mean of 8.3. Estimated mid-latitude A indices were 5, 5, 4, 4, 2, 6 and 13, with a mean of 5.6.
For more information concerning radio propagation, see the ARRL Technical Information Service. A detailed explanation of the numbers used in this bulletin can be found here. An archive of past propagation bulletins can be found here. Monthly propagation charts between four USA regions and 12 overseas locations are available at http://www.arrl.org/qst/propcharts/.
Amateur solar observer Tad Cook, K7RA, 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 in The ARRL Letter. Readers may contact the author via e-mail.
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