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 Previous: Youth@HamRadio.Fun: Young Hams Assist with Hurricane Relief and more! | ![Next (later) Story](/images/sty-up.gif ""Uncooperative" Hurricane Wilma Alters Activation Plans"){kind=small} Next: "Uncooperative" Hurricane Wilma Alters Activation Plans |
SEATTLE, WA, Oct 21, 2005--Solar activity continues at low levels. During the reporting week, every day but Wednesday, October 19, had a sunspot number of 11. Average daily sunspot numbers were down 8 points. Geomagnetic conditions were also quiet.
Conditions for the near term look the same, with solar flux around 78 and geomagnetic conditions quiet to unsettled. Geophysical Institute Prague predicts quiet conditions October 21 and 23, quiet to unsettled October 25-27, and unsettled conditions October 22 and 24. A forecast from the US Air Force shows planetary A index for today, October 21, at 5, and a planetary A index around 12 for October 22-29.
Last week's "Solar Update" discussed the quarterly averages of daily sunspot numbers with respect to trying to determine the bottom of the solar cycle. Carl Luetzelschwab, K9LA, mentioned that there haven't been any sunspots from a new solar cycle yet (they switch magnetic polarity) and referred to an interesting paper that talks about the bottom of the last cycle.
Carl highlighted the paragraph under Solar Activity, in which Karen Harvey talks about the various factors that come into play when trying to determine the minimum between the last and the next sunspot cycle. Not only must the sunspot numbers be low, but for a new cycle to be observed there must be a transition to a majority of new-cycle spots compared to a minority of sunspots from the old cycle. I believe the next Solar Cycle Prediction Panel meeting is in spring 2006, so perhaps we'll know more then.
Graham Rogers, VK6RO wrote to say that he thinks of the bottom of the cycle when the solar flux reaches 66.
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 October 13 through 19 were 11, 11, 11, 11, 11, 11 and 30, with a mean of 13.7. The 10.7 cm flux was 78, 78.4, 79.6, 79.2, 78.1, 78.3, and 77.9, with a mean of 78.5. Estimated planetary A indices were 4, 2, 2, 8, 13, 5 and 7, with a mean of 5.9. Estimated mid-latitude A indices were 2, 1, 2, 5, 7, 5 and 3, with a mean of 3.6.
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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