ARRL

ARRL Propagation Bulletin ARLP002 (2002)

SB PROP @ ARL $ARLP002
ARLP002 Propagation de K7VVV

ZCZC AP02
QST de W1AW  
Propagation Forecast Bulletin 2  ARLP002
From Tad Cook, K7VVV
Seattle, WA  January 11, 2002
To all radio amateurs 

SB PROP ARL ARLP002
ARLP002 Propagation de K7VVV

Solar activity has been lower over the past week. Average daily
sunspot numbers during the week of January 3-9 were nearly 52 points
less than the previous week, and average daily solar flux dropped by
42 points. Along with less sunspots there was very little
geomagnetic activity, which is great for HF propagation because of
lower absorption. Many periods over the past week had planetary and
mid-latitude K indices of 0 or 1.

Solar flux probably reached a short term minimum when it was 188.6
on Monday. Predicted solar flux for Friday through Monday is 230,
235, 240 and 245. Solar flux should peak near 260 around next
Thursday or Friday, then reach another short term minimum during the
first week of February.

Did we say this week was quiet? This won't last. A high speed stream
of energy from a coronal hole is due, and the predicted planetary A
index indicates a geomagnetic storm. Values for Friday through
Sunday should be around 30, 20 and 15. There was also a large solar
flare at 1801z on Wednesday. Although it came from a sunspot near
the center of the visible solar disk, the blast of energy from this
flare should not bother earth.

AD4JE wrote to suggest a good introduction to HF propagation at
http://www.ips.gov.au/papers/richard/prop_intro.html . He also asked
about web sites for solar flux, A and K indices, and I referred him
to http://www.drao.nrc.ca/icarus/www/current.txt ,
gopher://sec.noaa.gov/00/indices/DSD and
gopher://solar.sec.noaa.gov/00/latest/DGD .

KC7GOL also wrote to suggest NASA's Space Weather site at
http://spaceweather.com/ .

Several readers wrote to ask about a problem last week using the
WA4TTK graphing software with last week's bulletin. This software
can grab the data from the bulletin automatically, but last week the
use of a phrase in the text of the bulletin which was similar to one
at the end in the data area caused a parsing error. WA4TTK has an
explanation for these problems and their solutions at
http://www.craigcentral.com/solerr.htm . You can download his
software at http://www.craigcentral.com/sol.htm . With recent
versions of the solar plotting software, you can use the ftp
function and grab data from the ARRL to update the data file,
instead of entering it by hand or having the software grab the data
from your copy of the bulletin.

Sunspot numbers for January 3 through 9 were 229, 248, 201, 143,
158, 143 and 159 with a mean of 183. 10.7 cm flux was 220.3, 218.2,
212.2, 196.6, 188.6, 199.2 and 228.5, with a mean of 209.1, and
estimated planetary A indices were 3, 3, 3, 4, 7, 7 and 3 with a
mean of 4.3.
NNNN
/EX