 Previous: Surfin': Don't Stop Surfin' |  Next: Senate Bill Calls on FCC to Investigate BPL Interference Potential |
Expect low sunspot activity and moderate geomagnetic conditions this next week. Higher geomagnetic activity is predicted for June 19 and again on June 22. The US Air Force predicts the planetary A index from June 15-24 (June 23-24 is ARRL Field Day) at 10, 5, 5, 10, 20, 15, 12, 20, 12 and 5. Geophysical Institute Prague predicts unsettled conditions for June 15, quiet to unsettled on June 16-17, quiet on June 18-19, unsettled June 20, and unsettled to active conditions on June 21.
Sunspot numbers for June 7 through 13 were 59, 51, 19, 14, 13, 12 and 12 with a mean of 25.7. 10.7 cm flux was 85.5, 84.3, 78.6, 75.9, 73.3, 70.4, and 70.9, with a mean of 77. Estimated planetary A indices were 3, 8, 8, 8, 2, 4 and 5 with a mean of 5.4. Estimated mid-latitude A indices were 1, 7, 5, 6, 1, 3 and 5, with a mean of 4. These numbers show that average daily sunspot numbers for June 7-13 are down over 20 points, compared to May 31 through June 6. Average daily solar flux declined over five points.
In last week's bulletin, we had erroneous solar flux values for June 5-6. Instead of 88.8 on June 5, the solar flux was actually 81.2. On June 6 the flux value was 84.6, not 87.1. This means the average solar flux for May 31 through June 6 was actually 82.2, not 83.7. If you use the WA4TTK Solar Data Plotter, be sure to edit the values for those dates.
The solar flux numbers for two days of last week were estimated, rather than actual, because there was a server change, and new data was not at the old location on the Web; there is now a new site for the data. The official solar flux is the local noon reading, at 2000 UTC, listed in the fluxtime column of the table. The fluxobsflux column holds the three daily solar flux readings.
There has been another change in the prediction for smoothed sunspot numbers for this year, and the latest figures show the cycle minimum may have been three months ago, in March.
If you look at the previous forecast in the NOAA SEC Preliminary Report and Forecast for May 1 (check page 10 in issue PRF 1652), the minimum smoothed sunspot number is 11, stretching from January through June of this year. But if you look in the current June 12 issue on page 12, it shows the minimum of 11 for just one month, March 2007. Check back issues of this bulletin for observations on smoothed sunspot numbers, how they are calculated, and what they mean. NOAA has a page on smoothed sunspot numbers, as well.
Dave Colton, VO1TK of St John's, Newfoundland, e-mailed comments regarding recent conditions and activity on the bands. "Bands seem to be improving a little here lately. It never ceases to amaze me how 15 meters seems to come alive whenever there is a contest on but remain dormant otherwise. During the CQ WW WPX contest, 15 was open well into the evening and past sunset. I got into New Zealand with 100 W and a wire antenna, again on 15 meters".
Dave continues, "Several days ago, in the early evening, 20 meters was open but uncommonly noisy. When I checked 40 meters however, it was open and very, very quiet which is nothing short of a miracle at my QTH".
I've noticed this as well, that frequently beacons demonstrate that a band such as 15 or 17 meters is open to areas some distance away, and propagation software has predicted it, but activity is low enough when I'm on that it takes quite a bit of calling to raise someone. This is particularly noticeable when operating on a weekday, rather than a weekend day.
Pat Hamel, W5THT of Long Beach, Mississippi experiments with 600 meters, which is the old 500 KHz maritime distress frequency, just below the AM broadcast band. You can see details on the experiments, and location of the stations. Don't miss the link to the maps of reception reports, and another link to photos of the stations.
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 http://www.arrl.org/qst/propcharts/
If you would like to make a comment, or you have a tip for our readers, please e-mail the author.
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.
| Previous: Surfin': Don't Stop Surfin' | Next: Senate Bill Calls on FCC to Investigate BPL Interference Potential |