ZCZC AP32
QST de W1AW
Propagation Forecast Bulletin 32 ARLP032
From Tad Cook, K7VVV
Seattle, WA August 3, 2001
To all radio amateurs
SB PROP ARL ARLP032
ARLP032 Propagation de K7VVV
Average daily sunspot numbers dropped again this week, this time by nearly 64 points. The average daily solar flux dropped over 20 points. On July 31 the planetary A index rose to 23, the result of a solar wind stream. Geomagnetic activity on that day caused some impressive auroral displays.
Solar flux is predicted to be 125 for Friday, and around 130 for Saturday through Monday. Currently flux values are expected to rise slowly to 140 by August 10. A holographic image of the sun's far side taken on July 30 shows what may be a large group of sunspots, so there may be more activity rolling around in a couple of weeks.
Geomagnetic activity could be active again on Friday, settling down to unsettled for the weekend. The planetary A index for Friday is predicted to be 20, and 15 for Saturday and Sunday.
With July just ended, here are monthly averages for sunspot numbers and solar flux from the beginning of the year. Average daily sunspot numbers, January through July were 142.7, 131, 166.7, 163.6, 135.1, 196.7 and 124.6. Average daily solar flux readings for the same months were 166.6, 147.2, 177.7, 178.2, 148.7, 173.7 and 131.3.
There was a rise in activity during June, similar to the one around the end of March and beginning of April, but not as high. The monthly solar flux average for June probably beats March and April because the high activity earlier in the year was split over the two months.
Sunspot numbers for July 26 through August 1 were 115, 96, 88, 59, 64, 85 and 108 with a mean of 87.9. 10.7 cm flux was 123.4, 121.4, 115.5, 116.9, 114.5, 116.8 and 120.2, with a mean of 118.4, and estimated planetary A indices were 14, 9, 5, 8, 9, 23 and 12 with a mean of 11.4.