ARRL

ARRL Propagation Bulletin ARLP052 (2010)

SB PROP @ ARL $ARLP052
ARLP052 Propagation de K7RA

ZCZC AP52
QST de W1AW  
Propagation Forecast Bulletin 52  ARLP052
From Tad Cook, K7RA
Seattle, WA  December 30, 2010
To all radio amateurs 

SB PROP ARL ARLP052
ARLP052 Propagation de K7RA

There were no sunspots for a full week, from December 18-24.
Christmas day saw a return to sunspot activity, so the last two of
those spotless days were in the Thursday through Wednesday reporting
period in this bulletin, December 23-29.

Average daily sunspot number for this past week rose nearly 15
points to 19.7, and average daily solar flux was about the same as
last week.  It changed from 80.1 to 80.3.

The latest forecast from NOAA/USAF shows solar flux for December 31
through January 10 at 83, 84, 84, 82, 80, 80, 80, 83, 88, 88 and 88.
Predicted planetary A index 5 on December 31 through January 2, 7 on
January 3-6, and 5 again on January 7-10.

Our report from Geophysical Institute Prague predicts quiet
conditions December 31 to January 3, unsettled geomagnetic
conditions January 4, quiet to unsettled January 5, and quiet again
on January 6.

Although there are two more days of sunspot and solar flux readings
to complete the 2010 data, with 363 data points we can easily
calculate the year's averages.

Yearly averages of daily sunspot numbers for 2004-2010 were, 68.6,
48.9, 26.1, 12.8, 4.7, 5.1 and 25.5.

Yearly averages of daily noon 10.7 cm solar flux readings from
Penticton for 2004-2010 were 106.6, 91.9, 79.9, 73.1, 69, 70.6 and
80.

These averages represent a nice increase in solar activity, but they
still indicate a weak solar cycle.  We can compare these averages
with yearly averages around the end of the previous solar cycle.
Cycle 23 probably ended in late 2008, and Cycle 22 ended in
mid-1996, so averages based on calendar year are somewhat skewed,
whereas counting 365 day periods or perhaps shorter increments after
the end of a cycle would not be.

For 1993-1998, yearly averages of daily sunspot numbers were 79,
48.1, 28.7, 13.2, 30.7 and 88.7.  Over the same period the yearly
averages of daily solar flux were 109.5, 85.8, 77.1, 72, 81 and
117.9.

But looking over the data at hand, as presented, tells us that the
activity at the minima between Cycles 23 and 24 was lower than
between 22 and 23, and Cycle 24 still seems to be advancing much
more slowly.

Perhaps at another time we could examine the averages over shorter
periods following each minimum.

Last week's bulletin neglected to mention the propagation column in
the January 2011 issue of Worldradio by Carl Luetzelschwab, K9LA.
This is available for free online on the 20th day of each month.
This time Carl gives a careful analysis of skewed long-path
propagation on 40 meter CW between G3WW and YB0AZ, England to
Indonesia.  You can find it at http://www.worldradiomagazine.com,
and Carl's column runs from pages 38-40.

Jon Jones, N0JK regularly reports on E-skip openings on 6 meters.
This time he wrote, "Finally another winter season Es opening.  From
Wichita EM17 I worked K4UI EM76 with very loud signals at 0117 UTC
December 27.  Also heard a couple of '5s' in EL09 and K5AB/b EM10.
Most of it was going overhead as was too close in for most of the
Es."

You can take a look at this opening by querying
http://www.vhfdx.info/spots/.  He listed contacts from 0111z-0125z
on December 27.  Just leave everything at default, but select 50
MHz, Reported from 27 December 2010 at 0110 UTC until 27 December
2010 at 0130 UTC, and select the maximum number of returned QSOs at
100 or 250.  Click on "Submit Query," and you will see the listing.

You can also click on the NA Map tab to see a map of the paths
reported.  And if you want, you can expand the times in your query
to see more than what Jon reported.  Note that if you don't see QSOs
listed all the way to the early and late times you've entered,
either you have hit the 250 QSO limit, or there were no QSOs
reported during that period.  If you hit the limit, then just narrow
the time period, and also move the period forward and backward in
time to get a full report on 6 meter openings.  Also note that you
can restrict the report to paths greater than some arbitrary value.

Jon also reported working Canada on 6 meter CW on December 28, VE3EN
at 0214 UTC and VE2XK at 0309 UTC.  You can do a similar search to
examine this opening, too.

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 web page at
http://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation.  Find more good
information and tutorials on propagation at
http://mysite.ncnetwork.net/k9la/index.html.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.

Sunspot numbers for December 23 through 29 were 0, 0, 28, 28, 14,
31, and 37, with a mean of 19.7. 10.7 cm flux was 80.1, 78.6, 79.4,
80.5, 80.1, 80.7 and 82.6 with a mean of 80.3. Estimated planetary A
indices were 0, 3, 5, 2, 2, 13 and 3 with a mean of 4. Estimated
mid-latitude A indices were 1, 3, 4, 2, 1, 8 and 3 with a mean of
3.1.
NNNN
/EX