The K7VVV Solar Update

SEATTLE, WA, Dec 22, 2000--Average solar flux and sunspot numbers were up sharply this week. Solar flux average for the week was up more than 47 points, and sunspot numbers rose more than 85 points. It has been a quiet week geomagnetically, with planetary A indices in the single digits.

Solar flux probably peaked at 2200 UTC on December 20, when it reached 207.7. Solar flux is predicted over the next few days, Friday through Monday at 195, 195, 190 and 190. Planetary A index for those days is predicted at 12, 15, 15 and 12. The reason for the unsettled geomagnetic condition is a coronal mass ejection on December 18 that is expected to cause a weak disturbance.

Beyond this weekend look for solar flux to drop to a short term minimum around January 3-5 at 140. The next peak is expected from January 16-19.

Check the bottom of Jan Alvestad's Solar Terrestrial Activity Report. He has a table showing monthly averages of solar flux and sunspot numbers, as well as a smoothed sunspot number. According to his table, the highest average monthly solar flux was in March of this year, although July was almost as high. The highest sunspot number was in July, and during April he shows a smoothed sunspot number of 120.8, which may be the peak of this solar cycle. The peak of cycle 23 has probably passed, although we could get an increase in activity which would extend the peak. Fortunately, sunspot cycles seem to go up faster than they decline.

Sunspot numbers for December 14 through 20 were 157, 181, 217, 229, 174, 163 and 183 with a mean of 186.3. The 10.7-cm flux was 182.2, 187.8, 190.5, 196.7, 198, 198.6 and 201.3, with a mean of 193.6. The estimated planetary A indices were 4, 3, 4, 8, 10, 5 and 4 with a mean of 6.3.

Amateur solar observer Tad Cook, K7VVV Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version also appears in The ARRL Letter. Readers may contact the author via k7vvv@arrl.net.

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