ARRL

ARRL Propagation Bulletin ARLP042 (2001)

SB PROP @ ARL $ARLP042
ARLP042 Propagation de K7VVV

ZCZC AP42
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.
NNNN
/EX