Register Account

Login Help

ARRL Propagation Bulletin ARLP001 (2005)

ARLP001 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, K7RA
Seattle, WA  January 7, 2005
To all radio amateurs 

ARLP001 Propagation de K7RA

Happy New Year! Not much to say about solar numbers or propagation
this week compared to last, except that Thursday, January 6 had
wonderfully quiet geomagnetic numbers. Both mid-latitude and the
planetary A index were 4, and for most of the three-hour periods the
K index was 0 or 1.

Of course, sunspot numbers will continue their decline for the next
couple of years, but at least we can count on better conditions for
the near term as the hours of daylight lengthen.

Because the year is now 2005, we can tally up numbers for the
previous year and compare them with the past to try to get a feeling
for Cycle 23's decline. These quarterly and yearly averages are made
from the daily sunspot and solar flux data reported at the end of
each bulletin.

From the third quarter of 2003 through the fourth quarter of 2004,
average daily sunspot numbers were 110.2, 99.2, 72.9, 71.3, 69.3,
and 61. The average daily solar flux for the same period was 120.8,
137.4, 111.1, 99.5, 111 and 104.8.

Both the quarterly sunspot numbers and flux values have declined
steadily, although there are some variations, such as solar flux in
the fourth quarter of 2004 being higher than it was in the second

Average daily sunspot numbers for the years 2000 through 2004 were
173, 170.3, 176.6, 109.2 and 68.6. Average daily solar flux for the
same five years was 179.6, 181.6, 179.5, 129.2 and 106.6. We can see
the steady decline with each calendar year, and this should continue
through the end of next year, 2006.

Now for conditions over the short term, a week ago it looked like
solar flux should stay above 100 over the following 10-12 days. Now
the last of sunspot 715 is disappearing around the edge of the sun,
and it looks like solar flux should stay around 85 with sunspot
numbers below 40 over the next week.

Saturday, January 8 could see some unsettled to active geomagnetic
conditions, and January 13 could see unsettled conditions as well.
Quiet days are expected January 10-11.

Alan Beck, VY2WU from Prince Edward Island wrote in response to last
week's mention of 60 meters. He said in Northern Canada 60 meters is
used for "bush radio," and he told a story about Inuit hunters in
Nunavut using 5.2 MHz SSB at 10 watts to call home from the ice.

Barry Roseman, W0LHK of Stilwell, Kansas wrote to say he was on 60
meters the first day it opened for U.S. hams. Barry says only four
stations have worked all states on 60 meters: K7NN, N1UU, K4AVC, and
himself, W0LHK. His best DX was G0HNW in Yorkshire. Barry has used
various dipole antennas and a quarter-wave vertical, and says he
often works mobile stations.

If you would like to comment or have a tip, email the author at,

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at, .

Sunspot numbers for December 30 through January 5 were 34, 60, 51,
52, 43, 30 and 15 with a mean of 40.7. 10.7 cm flux was 100, 98.5,
98.9, 100, 94.2, 88 and 88, with a mean of 95.4. Estimated planetary
A indices were 15, 8, 15, 33, 22, 23 and 21 with a mean of 19.6.
Estimated mid-latitude A indices were 12, 5, 10, 20, 14, 16 and 11,
with a mean of 12.6.


Instragram     Facebook     Twitter     YouTube     LinkedIn