ARRL

ARRL Propagation Bulletin ARLP030 (2012)

SB PROP @ ARL $ARLP030
ARLP030 Propagation de K7RA

ZCZC AP31
QST de W1AW  
Propagation Forecast Bulletin 30  ARLP030
From Tad Cook, K7RA
Seattle, WA  July 27, 2012
To all radio amateurs 

SB PROP ARL ARLP030
ARLP030 Propagation de K7RA

The bulletin this week comes from Chicago, Illinois, where K7RA is
on the road.
 
We currently see new sunspot groups coming over our Sun's eastern
horizon, but this week has been a quiet one, both in terms of
sunspot and geomagnetic activity.  Average daily sunspot numbers
declined by fifty-percent, from 104.7 to 52.1, and average daily
solar flux was down nearly 45 points to 97.2.  This is comparing two
reporting periods, July 19-25 against July 12-18.
 
The latest solar flux forecast from NOAA/USAF has flux values at 115
for July 27-28, then 120, 125 and 130 on July 29-31, 135 on August
1-3, 130 on August 4-6, 125 on August 7-8, and 115 on August 9-11,
then bottoming out around 90 on August 17.
 
Predicted planetary A index is 5, 15, 18, 12 and 10 on July 27-31, 5
on August 1-3, 10 on August 4, and 5 on August 5-18.  There is
possible geomagnetic activity raising A index values to 15 and 12 on
August 19-20, then 18 on August 24-25.
 
F.K. Janda, OK1HH sends us his own geomagnetic forecast, and this
week he predicts active to disturbed conditions July 27-29, mostly
quiet on July 30, quiet on July 31, active to disturbed again on
August 1-2, mostly quiet August 3-4, active to disturbed August 5,
quiet to unsettled August 6-7, mostly quiet August 8, quiet August
9, active to disturbed August 10-11, quiet to active August 12-13,
mostly quiet August 14-15, and quiet to active August 16-17.
 
Astronomy Magazine has an article about a July 11 experiment in
which a telescope was lifted by a sounding rocket to take high
definition photos of the Sun's corona at extreme ultra-violet
wavelengths.  Read about it at
http://www.astronomy.com/~/link.aspx?_id=fd4b216b-fb6f-4a5e-
9a60-f593af862f38.  David Moore sent a link to a similar article
from the Astronomy Now web site,
http://www.astronomynow.com/news/n1207/24hic/.
 
Rob Steenburgh, KA8JBY, sent some interesting statistics regarding
the NOAA 45 day outlook/prediction for solar flux that is updated
daily at http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html.  You
can see the data collection here:
http://www.swpc.noaa.gov/forecast_verification/F10.html.
 
Note the link at the bottom of the page for "Forecast Skill vs. Lead
Time".  As I understand it, "Persistence" refers to the chance that
the solar flux will be the same tomorrow (or up to 7 days in the
future) as it is today.  "Climatology" refers to some value
representing a recent average, and "Recurrence" is the chance that
the solar flux will be the same 27-28 days from now as it is today.
This represents one rotation of the Sun relative to Earth.
 
So to make this forecast, they look at a combination of these
factors, and also whether the activity from four weeks before is
increasing or decreasing.  What might be interesting is to find out
what effect the STEREO mission has on forecast accuracy, because
STEREO brought to us the ability to see what is happening everywhere
on the Sun.  See the continuously updated STEREO image at
http://stereo.gsfc.nasa.gov/.
 
As Rob put it in a recent email, "You are right about the 45 day
forecast - a bit of persistence at the beginning, then more and more
recurrence and climatology later in the forecast.  Stereo has helped
- we can watch regions coming around on STEREO-B, and in a
qualitative sense, tell if they're larger or smaller.  It would be
interesting to take a look at the F10.7 stats and see if there's a
statistically significant difference in our forecasts since STEREO
went up."
 
Rich Zwirko, K1HTV of Amissville, Virginia wrote:  "The 6M band
opened on Tuesday, July 24 at around 1200Z to Puerto Rico, CT
(that's Portugal, not Connecticut), F and G.  Two FP stations also
showed up to liven up the Magic Band.  Then around 1515Z, 144 MHz
came alive with E skip.
 
The first round started around 1525Z when he worked Florida
stations, W4AS, EL95TO, N2OTO, EL96WI (worked on 2M SSB than again
later on 146.52 FM), N3LL, EL86TX."
 
"The last station heard was W4AS at 1610Z, then 2M quieted down.  I
didn't get back on the air until 2110Z and found 6 Meters hot as a
pistol.  I worked 66 stations in the next 50 minutes.  At 2200Z, I
noticed on thewww.vhfdx.info MUF map page that the MUF had climbed
to over 145 MHz to the west of here.  I quickly changed frequency on
the IC706 to 144.200MHz and started to hear and work E skip stations
to the west and eventually southwest."
 
The 66 stations he worked were in Arkansas, Iowa, Illinois, Kansas,
Minnesota, Missouri, Oklahoma, Texas, Wisconsin, and West Virginia.
 
Rich wrote, "In this opening, the ionized E clouds favored OK(11),
MO(7), KS(4), IL(3), FL(3), WI(2), and one station each from TX, AR,
MN, and IA.  It was a fun day.  Too bad it didn't occur over the
weekend during the CQWW VHF contest.
 
My son Andy, K1RA, while driving home from work and operating 2M
mobile, also got into the fun.  He worked N0ICZ, K0NYW, W0BLD and
K5SW with 50 Watts and a mobile whip."
 
Reynolds Davis, K0GND of Lincoln, Nebraska forwarded a July 24 note
from Dave Theophlius, W0NRW of Fremont, Nebraska:
 
"Just like in 2009 and 2010, there was a major Sporadic E opening on
2 meters late this afternoon.  I had been keeping an eye on the DX
Sherlock site all day because the MUF kept popping above 100 MHz in
the southeast U.S.
 
Finally, at 2340Z it opened for me.  The cloud appeared to be over
the Ohio River Valley and I appeared to be on the west edge of
people able to make contacts.  I did hear W0KT in Omaha also making
contacts.  CT1HZE, who asked that logs be emailed to him, estimated
that the MUF rose to 274 MHZ as contacts were also being made on
220.
 
The VHF propagation map based on APRS stations was just a big blob
of red.
 
The opening only lasted about 10 minutes for me where signals were
strong enough to work anybody.  At 2340Z I worked NT4RT in EM94 in
South Carolina, and at 2346 I worked W4TMW in EM84 in Georgia.
 
And just as fast as it opened it was over for me, although stations
farther east continued to make contacts.
 
CT1HZE added a comment on the ON4KST chatroom that in Europe a major
opening like today is often followed by another one the following
day.  So, it might pay to keep an eye open on Wednesday if you are
into VHF DX.
 
And my antenna?  A 2 meter FM vertical polarized groundplane at 54
feet on my new tower.  Yes, Lance and Larry, the rotatable
groundplane.  The VHF/UHF beams are not up yet.
 
So, it appears that although VHF SSB/CW operators use horizontal
polarization, the polarization during Es openings may not be all
that important.  I think Lance, WN0L had the same experience during
one of the earlier openings.  But when Plan A is not operational, it
is time to go to Plan B, which is use anything that is available."
 
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://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://myplace.frontier.com/~k9la/.
 
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 July 19 through 25 were 39, 55, 50, 29, 60, 66,
and 66, with a mean of 52.1.  10.7 cm flux was 100, 92.3, 89.9,
93.7, 96.7, 102.4, and 105.4, with a mean of 97.2.  Estimated
planetary A indices were 6, 11, 11, 8, 9, 10, and 6, with a mean of
8.7.  Estimated mid-latitude A indices were 6, 10, 8, 9, 8, 10, and
6, with a mean of 8.1.
NNNN
/EX