SB PROP @ ARL $ARLP039
ARLP039 Propagation de K7RA

ZCZC AP39
QST de W1AW  
Propagation Forecast Bulletin 39  ARLP039
From Tad Cook, K7RA
Seattle, WA  September 26, 2014
To all radio amateurs 

SB PROP ARL ARLP039
ARLP039 Propagation de K7RA

Solar activity was down this week (September 18-24) when compared
with a week earlier, but solar flux is on a rising trend.

Average daily sunspot numbers dropped from 124.9 (for September
11-17) to 80.9, and average daily solar flux slipped from 139.8 to
128.3.

The latest predicted solar flux and planetary A index has flux
values at 165 on September 26-28, 170 on September 29-30, 165 and
160 on October 1-2, 155 on October 3-4, 150 on October 5-7, 145 on
October 8-9, 140 on October 10-11, then 135 and 130 on October
12-13, 125 on October 14-15, and 120 on October 16-18. Flux values
are then expected to rise to 155 on October 30-31.

Predicted planetary A index is 15 on September 26, 12 on September
27, 15 on September 28-29, 10 on September 30, 8 on October 1-2, 5
on October 3-14, then 8, 15 and 8 on October 15-17, 5 on October
18-19, 8 on October 20-21, 12 on October 22, and 15 on October
23-24.

Petr Kolman, OK1MGW makes geomagnetic predictions, and believes the
geomagnetic field will be quiet to active September 26-27, quiet to
active September 28 through October 3, mostly quiet October 4-7,
quiet to unsettled October 8-9, quiet October 10-12, mostly quiet
October 13, quiet to active October 14-15, mostly quiet October
16-17, quiet to unsettled October 18-20, and quiet to active on
October 21-22.

Earth's geomagnetic field has been unsettled recently, with
planetary A index at 25 on September 24 and College A index (high
latitude) at 57. Spaceweather.com reports this is not due to a CME
or solar flare, but a crack in the Earth's magnetosphere, opening a
spot for the solar wind to pour in.

John Campbell, K4NFE of Huntsville, Alabama sent in an article and
video explaining the difference between solar flares and Coronal
Mass Ejections.

Read it at,
http://www.universetoday.com/114729/nasa-explains-the-difference-between-cmes-and-solar-flares/
.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at
http://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.

Sunspot numbers for September 18 through 24 were 75, 91, 75, 72, 87,
90, and 76, with a mean of 80.9. 10.7 cm flux was 120, 122, 119,
124, 130, 138, and 145, with a mean of 128.3. Estimated planetary A
indices were 8, 22, 6, 7, 9, 11, and 25, with a mean of 12.6.
Estimated mid-latitude A indices were 7, 23, 4, 7, 9, 9, and 19,
with a mean of 11.1.
NNNN
/EX