The K7RA Solar Update

SEATTLE, WA, Feb 3, 2006--Solar activity is very low! Average
daily sunspot numbers for the week were down by more than 40
points to 9.1. Average daily solar flux dropped nearly 11 points to
80.6. Geomagnetic conditions, with the exception of January 26,
were stable and quiet. On January 26 the interplanetary magnetic
field, which can shield Earth from solar wind if it is pointing north,
turned south, and the mid-latitudes experienced some moderate
geomagnetic activity, with the A index for the day at 15. Polar
regions saw a lot more activity, with the College A index in Alaska
going to 36.

The sun has been spotless since January 29, and daily readings of
zero sunspots could continue for another week. We will observe
more and longer periods such as this as we head toward the solar
minimum, still expected about to occur about a year from now.
Geomagnetic conditions should remain quiet and solar flux at
around 77. It may not begin to rise again until February 10.

January is over, so let us examine the average daily solar flux and
sunspot numbers for the month compared with previous months. The average daily
sunspot
numbers for the months January 2005 through January 2006 were 52, 45.4, 41,
41.5, 65.4,
59.8, 68.7, 65.6, 39.2, 13, 32.2, 62.6 and 26.7. Average daily solar flux for
the same months was
102.3, 97.2, 89.9, 85.9, 99.5, 93.7, 96.5, 92.4, 91.9, 76.6, 86.3, 90.8 and
86.6.

As expected, the solar cycle is declining, but there is a lot of variation from
month to month.

Richard Buckner wrote regarding last week's mention of the ACE-HF and ACE-HF Pro
System
Simulation and Visualization Software for propagation prediction. He says ACE-HF
can do
160-meter predictions, but with some limitations. He cites the ACE-HF "Basis for
Predictions"
tutorial, written by George Lane:

"160-m frequencies are rounded to 2.0 MHz to conform to VOACAP's lower frequency
limit.
VOACAP 2-MHz predictions are reasonably accurate for NVIS and short-range
predictions out
to about 1500 km. But when path distances are very long, VOACAP becomes less
accurate at
night. At night, a residual E-layer exists with a MUF usually above 2 MHz. It is
this phenomenon
that permits AM broadcasts in the medium-wave bands to propagate thousands of
kilometers
during nighttime hours. VOACAP, however, is based on data that was collected at
frequencies
of 4 MHz and higher. Extrapolation was used to cover the lower frequencies, but
funding
limitations prevented the collection of further data to support those
extrapolations. Unfortunately,
computed absorption values are excessive in the extrapolations and the nighttime
predictions
thus become excessively attenuated as path distance increases. For this reason,
160-m
nighttime predictions at long path distances should be used with caution."

We heard again from Charles Lewis, S9SS, on Sao Tome--an island off the West
African coast,
west of Gabon. On January 20 he wrote:

"I made 150 160-meter contacts last week. 51 were in North America, coast to
coast. It was, as
usual, very slow, tedious going. E-mails to me cited large pileups. As usual, I
heard no pileup.
Usually, I hear only one, occasionally two, stations cresting my high level
noise. Even most 'big
gun' stations only get through when their signal is enhanced greatly by whatever
propagation
phenomenon. Even 'little guns' find themselves all alone in the spotlight on my
stage now and
then, despite all the better equipped callers. There is no such thing as
cracking the pileup on me
on 160 meters, since I never hear it.

"In the Stew Perry [contest], I heard only five NA stations in close to three
hours of listening and
worked all five easily. It was interesting that I heard one station on and off
for nearly two hours,
while I heard the others only briefly for one period.

"An interesting quirk here is a rogue LU 10-meter beacon that I hear often on
the IARU beacon
frequency for hours at a time when the band is so dead that I hear none of the
IARU beacons.
Weird!! I favor the W3VD beacon when I am specifically looking for an opening to
the USA on 10
meters since, unlike 4U1UN, it transmits continuously on 10 M.

"I used to experience the antipodes enhancement phenomenon on the upper bands
often when I
was A22AA in 89-92. I would often work Hawaiian hams (and hear WWVH) when the
bands
were nearly in a blackout condition."

For more information concerning propagation and an explanation of the numbers
used in this
bulletin see the ARRL Technical Information Service Propagation page. An archive
of past
bulletins is on the ARRL Web site.

Sunspot numbers for January 26 through February 1 were 24, 29, 11, 0, 0, 0 and
0, with a mean
of 9.1. The 10.7 cm flux was 86.9, 83.5, 80, 79.5, 78.8, 77.6, and 77.6, with a
mean of 80.6.
Estimated planetary A indices were 29, 8, 6, 3, 1, 2 and 4, with a mean of 7.6.
Estimated
mid-latitude A indices were 15, 7, 4, 1, 0, 1 and 3, with a mean of 4.4.
(K7RA, ARRL)

dxAce
Michigan
USA