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 Previous: Hurricane Watch Net Alters Rita Activation Plans; ARES/RACES Gear Up |  Next: IARU Eyes Global Coordination of Amateur Radio's BPL/EMC Response |
SEATTLE, WA, Sep 23, 2005--Solar activity quieted down this week after a recent tumultuous period marked by aurora and geomagnetic storms. Average daily sunspot numbers dropped to 46--more than 25 points below the previous week. Average daily solar flux declined by more than 9 points to 100.3.
Sunspot numbers are expected to stay low, rising again after October 3. Geomagnetic conditions should also stay low, with unsettled conditions possible around September 27-29. Geophysical Institute Prague predicts quiet to unsettled conditions September 23-24, quiet September 25-26, active conditions September 27 and unsettled conditions September 28-29.
Fall has now begun. Despite the low solar activity, conditions are more seasonally favorable for HF propagation. The lower geomagnetic activity is a plus for HF conditions.
We received more mail on 80-meter propagation at the bottom of the solar cycle. David Beckwith, W2QM, of Delray Beach, Florida, believes that "seemingly better conditions during the low point of the cycle" may owe more to increased activity on the lower bands because the higher bands are so poor. Good point! David should know. He's been on the air since 1938--even during World War II, when he was an infantry radio operator in Europe. According to his biography, he's worked 380 countries, including all except North Korea on the current DXCC list.
Ed Douglass, AA9OZ, mentions John Devoldere's book, ON4UN's Low-Band DXing. "ON4UN's explanation for good propagation on 80 and 160 during sunspot minima is that with less solar UV radiation, there is less density in the D-layer in the earth's atmosphere," he noted. "Furthermore, the formation of the D-layer is slower, particularly during the winter months in either hemisphere. As you know, it is the D-layer that tends to absorb lower HF signals, most notably preventing the propagation of signals during local daylight hours."
Douglass says that in addition to our explanation that a less active sun will produce less-intense disturbances in the ionosphere and improved propagation through the auroral zones, east-west path propagation will be better because there will be longer periods when there is no D-layer. He notes that Devoldere's book delves into this topic very thoroughly and is a great asset for those serious about DXing on the lower bands.
Douglass also notes that as thunderstorm activity drops in the northern hemisphere with the transition into winter, weaker DX signals once again are audible above the noise.
John Shannon, K3WWP, is a 100-percent CW and QRP operator. He writes: "My antenna for 80 and 160 is a random wire in my attic. In the two big 160-meter contests--ARRL and CQ--with my simple setup it was fairly easy for me to work around 250 QSOs during the sunspot minimum back in the 90s." He says that included working West Coast stations.
"At sunspot maximum I had to struggle to make 50 or 60 QSOs and usually gave up out of frustration at no one hearing me or having to repeat my info many times over to virtually every station," he goes on to say. "I couldn't work anyone west of the Mississippi River at the maximum."
Shannon says that on 80 meters he can usually work Europe near the minimum, but it is rough near a maximum. "So based on personal experience, I would say low band conditions are definitely better at or near a minimum," he concludes.
Russell Hunt, WQ3X, reports he's still working DX on 10 meters. On September 15, he says, he worked CN8KD, CT4GO and EA1CBX on 10-meter SSB starting at 2200 UTC, when the local time at the other end of the circuit was 11 PM. "Signals were amazingly strong, but the opening only lasted about a half-hour," he said. "It was incredible! I was able to hear most of the USA stations working the DX also."
I ran some path projections using a popular propagation program mentioned in past bulletins, and found that from his location in Pennsylvania to Spain, Morocco and Portugal there is still good likelihood of 10-meter openings ending around the time John made his contacts. Be sure to check out John's Web site devoted to some work he's done refurbishing classic radio gear.
Last, we hear from Bill Clark, N0MAM. "I became licensed in 1996 when many experienced hams were complaining about the bands," he writes. "At that time I had the call KB0TNM. I began working 40 meters on the Novice CW band, and many experienced hams complained that it was too noisy a band to work." Clark says he was on every night making domestic contacts, working 30 states that summer and winter--mostly in the East and West. "I worked Hawaii, Alaska, Mexico and many Canadian contacts. It put me well on the way to getting WAS on 40-meter CW. I didn't know what all the complaints about 40 meters being noisy were about until 1998, when the bands came up and all the Latin American AM stations created so much whine that I had to abandon it. It was a lot of fun and good experience for me as a new operator, and I didn't even know that I wasn't supposed to be enjoying myself because the band was 'down.'"
For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page.
Sunspot numbers for September 15 through 21 were 77, 51, 59, 50, 43, 23 and 19, with a mean of 46. The 10.7 cm flux was 119.4, 112, 103.9, 102.2, 91.1, 87.8, and 86, with a mean of 100.3. Estimated planetary A indices were 43, 18, 12, 12, 8, 6 and 5, with a mean of 14.9. Estimated mid-latitude A indices were 22, 11, 10, 8, 8, 3 and 3, with a mean of 9.3.
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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