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 Previous: Surfin': More Brewing From Home |  Next: Chip Margelli, K7JA, Moves to Heil Sound Ltd |
SEATTLE, WA, Sep 15, 2006 -- The autumnal equinox for the Northern Hemisphere will occur September 23 at 0402 UTC. Fall is generally a better time for HF propagation, except for a lack of sporadic-E skip.
On 20 meters, instead of intercontinental openings into the evening, we see improved conditions well before dark. For instance, comparing projected conditions for this weekend from the East Coast to Europe with conditions in early July, 20-meters was marginal during the morning and mid-day, but became better late in the day.
Conditions between Pennsylvania and Germany around July 5 showed a projected jump in signal levels around 2200 UTC, then excellent propagation until around 0700 UTC. But for mid-September 20 meters over the same path has rising signals from morning until early evening, with signals dropping after 2300 UTC. Seventeen meters over the same path looks very good this weekend from 1230 UTC until 2130 UTC. The chances of a good path during July were much lower, except for a brief period around 0000-0030 UTC.
Average daily sunspot numbers rose over the past week by 19 points to 44.3. Geomagnetic conditions were quiet every day. For the next week Geophysical Institute Prague predicts quiet conditions for September 15, then quiet to unsettled on the September 16, unsettled geomagnetic activity on September 17 and 18, then quiet on September 19-21. The US Air Force spaceweather operation predicts planetary A index (a measure of geomagnetic activity) for September 15-21 at 5, 10, 12, 15, 8, 5 and 5.
Steve Hammer, K6SGH, of Santa Barbara, California asks a source for an archive of daily sunspot numbers that he might import into a spreadsheet. Al Woodhull, N1AW, of Amherst, Massachusetts, had a similar request. One handy source for this, which is easy to update using this bulletin, is the free Solar Data Plotting software from Scott Craig, WA4TTK. The program stores the daily sunspot number and solar flux going back to the late 1980s in a file called graph.dat. There is also a separate update to the data file with numbers up through the end of August. You can update the file semi-automatically by saving the weekly bulletin as a plain-text ASCII file, then using the software to read the file and suck up the data. To bring the current file up to date would only require a file made from this bulletin and another from last week's.
Gary Nixon, WA6HZT, of Fair Oaks, California, and Andy Gudas, N7TP, of Amargosa Valley, Nevada, both sent references to an article claiming that thunderstorms actually affect the ionosphere and radio propagation (other than causing QRN, of course).
Dick Bingham, W7WKR, of Stehekin, Washington, sent in a quote concerning 160 meters from Wolf Ostwald, DF2PY. "This year's West Coast window opened about 3 weeks earlier than in the last year's. K7RL and W1YY/7 made it into Eu today about 45min and 25 minutes prior to local sunrise. Their sigs were fantastic for topband standards, even good enough for 'ragchewing.' I take this as a good omen for the new season, and it repeatedly shows again the superiority of the CW mode to master difficult paths under any circumstance."
And finally, Bill Isakson, AC6QV, of El Cerrito, California, wrote this about 17 meters. "I thought, since you just now indicated a software result that not much should happen above 20 meters, that I should tell you that 17 meter activity has been great recently. Earlier this week I had QSO with a station in San Francisco, Argentina, from here in Berkeley -- near San Francisco, California -- for example, on my way home from work around 5 PM; that is, mobile on a HamStick. His S9 CW signals were mildly strong and clean in this electrically noisy environment, though mine at his end were weak." Bill says 17 meters has generally been open most afternoons on the West Coast, and he's heard Australia as well.
For More Information
For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page and the article "The Sun, the Earth, the Ionosphere: What the Numbers Mean, and Propagation Predictions," by Carl Luetzelschwab, K9LA. An archive of past bulletins is on the ARRL Web site.
Weekly Sunspot Numbers
Sunspot numbers for September 7 through 13 were 39, 49, 51, 50, 42, 41 and 38, with a mean of 44.3. The 10.7 cm flux was 86.7, 87.2, 85.5, 87.3, 84.6, 84.1, and 82.9, with a mean of 85.5. Estimated planetary A indices were 8, 4, 2, 6, 8, 4 and 6, with a mean of 5.4. Estimated mid-latitude A indices were 5, 4, 1, 5, 7, 2 and 3, with a mean of 3.9.
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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