QST de W1AW  
Propagation Forecast Bulletin 2  ARLP002
>From Tad Cook, K7RA
Seattle, WA  January 12, 2018
To all radio amateurs 

SB PROP ARL ARLP002
ARLP002 Propagation de K7RA

Average daily sunspot number was 11.9 over the past reporting week
(January 4-10, 2018) compared to zero (no sunspots) over the
previous seven days. But average daily solar flux declined slightly,
70.4 to 69.9.
 
Average daily planetary A index went from 5.1 to 5.4, and average
mid-latitude A index changed from 3.4 to 4.6.
 
Predicted solar flux is 70 on January 12-21, 72 on January 22-27, 70
on January 28 to February 17, 72 on February 18-23, and 70 on
February 24-25.
 
Predicted planetary A index is 5 on January 12, then 15, 12 and 8 on
January 13-15, 5 on January 16-19, then 12, 10, 8 and 6 on January
20-23, 5 on January 24-27, 10 on January 28, 5 on January 29 through
February 3, then 12, 8, 5 and 8 on February 4-7, 5 on February 8-9,
then 10, 15 and 10 on February 10-12, 5 on February 13-15, then 12,
10, 8 and 6 on February 16-19, 5 on February 20-23, 10 on February
24, and 5 on February 25.
 
'Geomagnetic activity forecast for the period January 12 to February
7, 2018
 
'Geomagnetic field will be: 
quiet on January 19, 26, 31, February 7 
mostly quiet on January 18, 25, 30, February 3, 6 
quiet to unsettled on January 12, 15, 20, 24, 29, February 2, 5 
quiet to active on January 14, 16, 21, 23, 27-28, February 1, 4 
active to disturbed on January 13, (17,) 22 
 
'Amplifications of the solar wind from coronal holes are expected on
January 12-14, 19-20, (21-22, 28-31, February 1,) 5-6, (7)
 
'Remark: 
- Parenthesis means lower probability of activity enhancement. 
- Current forecasts still is less reliable again. 
 
'F.K. Janda, OK1HH (from Czech Propagation Interested Group
compiling this geomagnetic activity weekly forecasts since 1978).
e-mail: [email protected] .'
 
Here is an article about a propagation mode I had not heard of,
Equatorial Spread-F:
 
bit.ly/2lYSaHO
 
Here is a fairly technical article about sunspots and temperature:
 
bit.ly/2Ey9hb6
 
Let's look at recent appearances of sunspots, and sunspot area.
 
If we look at recent sunspot numbers:
 
ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt
 
We see that new sunspots appeared on January 4, 8 and 11. (Check the
New Regions column, fifth from the left).
 
Also note in the fourth column, the 'Sunspot Area 10E-6 Hemis'
column.
 
This shows the area of total observed sunspots on the visible sun,
in millionths of a solar hemisphere. You can observe that the
sunspot area began at 20 (10E-6 Hemis.) on the first day of the new
sunspot group (on January 4). Note the same sunspot group contracted
to half that area for at least the following week.
 
You can check sunspot numbers, solar flux and sunspot area for 2017
at:
 
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2017_DSD.txt
 
Check out this resource on sunspot area, from Peter Meadows:
 
www.petermeadows.com/html/area.html#top
 
Note other resources from Peter:
 
www.petermeadows.com/
 
Interesting site for a private/public observatory in the UAE:
 
alsadeemastronomy.ae/

If you would like to make a comment or have a tip for our readers,
email the author at, [email protected] .
 
For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
arrl.org/propagation-of-rf-signals. For an explanation of
numbers used in this bulletin, see
arrl.org/the-sun-the-earth-the-ionosphere.
 
An archive of past propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation.  More good
information and tutorials on propagation are at k9la.us/.
 
Monthly propagation charts between four USA regions and twelve
overseas locations are at arrl.org/propagation.
 
Instructions for starting or ending email distribution of ARRL
bulletins are at arrl.org/bulletins.
 
Thanks to Don, AA2F/9 for checking my data averages.
 
Sunspot numbers for January 4-10, 2018 were 13, 11, 11, 11, 13, 13,
and 11, with a mean of 11.9. 10.7 cm flux was 69.5, 69.3, 69.4,
69.9, 70.3, 70.8, and 70.4, with a mean of 69.9.  Estimated
planetary A indices were 4, 5, 3, 3, 9, 9, and 5, with a mean of
5.4. Estimated mid- latitude A indices were 3, 5, 2, 2, 9, 7, and 4,
with a mean of 4.6.