QST de W1AW
Propagation Forecast Bulletin 42 ARLP042
From Tad Cook, K7VVV
Seattle, WA October 12, 2001
To all radio amateurs
SB PROP ARL ARLP042
ARLP042 Propagation de K7VVV
All indices were down this week. Average daily sunspot numbers were off 87 points from last week and nearly 133 points below the week before. Average daily solar flux has dropped nearly 57 points from last week and 82 points from the week before. Geomagnetic conditions were relatively stable this week, with the average daily planetary A index down 18.8 points. October 4 was fairly active, with a planetary A index of 19 and K indices as high as 5.
October 8 and 9 were unsettled with planetary A indices of 15 on both days, and a planetary K index as high as 4.
The latest forecast shows solar flux at 170 on Friday through Sunday, then rising to 185 by Wednesday. Holographic images of the far side of the sun show a large sunspot region that should appear around Monday or Tuesday. Look for a big jump in solar flux by next Friday, October 19 when the sunspot group moves toward optimal position for influencing earth.
For a treatise on helioseismology, which is used to sense the sunspots on the sun's far side, look on the web for http://science.msfc.nasa.gov/ssl/pad/solar/p_modes.htm.
This technique is used to generate the holographic images that tell us what is about to move around from the far side and into view.
Look at http://spaceweather.com/glossary/farside.html for information on helioseismic holography.
Sunspot numbers for October 4 through 10 were 231, 160, 181, 154, 130, 99 and 133 with a mean of 155.4. 10.7 cm flux was 186.5, 176.9, 180.4, 172.7, 171.2, 176.4 and 178.7, with a mean of 177.5, and estimated planetary A indices were 19, 9, 8, 4, 15, 15 and 8 with a mean of 11.1.