ARRL

ARRL Propagation Bulletin ARLP002 (2008)

SB PROP @ ARL $ARLP002
ARLP002 Propagation de K7RA

ZCZC AP02
QST de W1AW  
Propagation Forecast Bulletin 2  ARLP002
From Tad Cook, K7RA
Seattle, WA  January 11, 2008
To all radio amateurs 

SB PROP ARL ARLP002
ARLP002 Propagation de K7RA

We just saw eight days of sunspots, but now the solar disk is
spot-free.  The big story this week is the sighting of the first
spot of sunspot Cycle 24.  The sunspot has now faded away, but a new
spot is emerging near the solar equator, and it has the same
polarity as the Cycle 24 spot last week.  This is odd, because the
spots from the new cycle should emerge at high latitudes, like last
week's did.

News reports this week said Cycle 24 has begun, but actually Cycle
23 hasn't ended yet.  Cycle 24 spots should gradually increase in
number, while Cycle 23 spots fade away.  Some time around solar
minimum we should see the count of Cycle 24 spots equal, and then
outnumber Cycle 23 spots.  I believe that is really the start of the
next cycle, when we begin to see more Cycle 24 spots emerging than
Cycle 23 spots.

Average sunspot numbers this week were nearly 10 points above last
week's average, at 13.3.  Unsettled geomagnetic conditions were
observed on January 5-8.  Last week the prediction for solar flux
for earlier this week looked optimistic.  Go to
http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html and click on
the December 30 forecast.

Note the prediction for solar flux of 85 for January 4-11.  Then
click back, and look at December 31.  On that day it predicted a
solar flux of 90 for January 5-7.  The January 1 prediction is even
higher at solar flux 95 for January 7-8.  The next day, January 2
shows flux at 95 for January 7-9.  January 3 is less optimistic,
with flux peaking at 90 for January 9-11, although some of the dates
are mislabeled.  January 4 shows flux peaking for one day, January
6, at 85.  None of those predictions came to pass, and solar flux
was actually below 80 the entire week.

NOAA and the Air Force predict planetary A index values for January
11-17 at 5, 5, 15, 15, 10, 12 and 10.  If you want an updated
forecast after 2100z today, use the URL above and go to the January
10 forecast (if January 11 isn't shown yet).  Then change a series
of characters in the URL from 011045DF.txt to 011145DF.txt, and hit
the Enter key.  You should see an updated forecast for solar flux
and planetary A index before the link appears on the main page.

Australia's IPS Radio and Space Services released a warning for a
geomagnetic disturbance caused by a high speed solar wind stream
from a coronal hole for January 13-14.  This is reflected in the
forecast in the previous paragraph, calling for a planetary A index
of 15 for both those days.  Geophysical Institute Prague predicts
quiet conditions January 11-12, quiet to unsettled January 13,
active conditions January 14, unsettled to active January 15, and
unsettled conditions January 16-17.

For HF radio propagation, we would generally like to see sunspot
numbers high, and A index geomagnetic readings low.

Last week Randy Crews, W7TJ reported excellent short path
propagation to Europe on 160 and 80 meters on the night of January
3.  Bob Culbertson, WA3YGQ of Cranberry, Pennsylvania said 80 meter
propagation to Europe was the best he ever heard, with signals 20 db
over S9.  At 1230z he could hear Japan quiet strongly.

But Ken Gordon, W7EKB of Moscow, Idaho runs regional message traffic
on 80 meters, and reported that the same night he experienced
terrible conditions on 80 meters.  Ken was net control for the RN7
net on 3560 kHz at 0330z and again at 0530z, and he could hardly
hear anyone.  But stations sitting at 800 miles and beyond were
booming in.  Lately he's had an experience earlier in the evening on
a net at 0030z on 3910 kHz in which signals from Montana are
readable, but 10-15 minutes later they fade away and signals from
the West Coast come in quite strong.  The skip seems to be going
long.

Jon Jones, N0JK of Wichita, Kansas sent comments regarding 10 meter
Winter E-skip.  He noted a number of strong E-skip openings on
Saturday night in December's 10 Meter Contest.  He made many
contacts running QRP into a 6-meter loop.

Jon said he agrees with Bill Van Alstyne, W5WVO of Rio Rancho, New
Mexico, that "most of the winter E-skip occurs during late afternoon
and early evening hours. Summer E-skip tends to occur more
frequently in the mid-morning hours, with a secondary peak in the
evening."  He wonders why Winter and off-season E-skip is more
likely in the evening, but Summer E-skip seems more frequent in the
morning?

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 at,
http://www.arrl.org/tis/info/propagation.html.  For a detailed
explanation of the numbers used in this bulletin see,
http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past
propagation bulletins is at, http://www.arrl.org/w1aw/prop/ .
Monthly propagation charts between four USA regions and twelve
overseas locations are at, http://www.arrl.org/qst/propcharts/ .

Sunspot numbers for January 3 through 9 were 13, 26, 12, 12, 14, 16
and 0 with a mean of 13.3.  10.7 cm flux was 79.3, 79, 79.7, 79.2,
77.7, 75.5, and 76.5 with a mean of 78.1.  Estimated planetary A
indices were 1, 2, 18, 13, 12, 13 and 6 with a mean of 9.3.
Estimated mid-latitude A indices were 1, 2, 13, 12, 10, 11 and 6,
with a mean of 7.9.
NNNN
/EX