ARRL

ARRL Propagation Bulletin ARLP021 (2014)

SB PROP @ ARL $ARLP021
ARLP021 Propagation de K7RA

ZCZC AP21
QST de W1AW  
Propagation Forecast Bulletin 21  ARLP021
From Tad Cook, K7RA
Seattle, WA  May 23, 2014
To all radio amateurs 

SB PROP ARL ARLP021
ARLP021 Propagation de K7RA

Over the past week we saw a decline in solar activity, and the
45-day outlook showed progressively weaker numbers as well.
 
Average daily sunspot numbers for May 15 to 21 were 129.4, while the
previous average was 142.4, a 13 point decline. Average daily solar
flux drifted from 157.5 to 128.5. The daily sunspot number on
Wednesday dropped down to 100 and on Thursday it was only 70, a
level unseen seen since January 28.
 
Last week the solar flux prediction for Friday through Sunday on
Field Day (June 28 and 29) was 125 on Friday and 135 on Saturday and
Sunday. But the daily forecast on May 19 changed, with predicted
solar flux at 120 on all three days, where it still remains. Prior
to May 19 solar flux was predicted to peak at 165 on June 10 and 11,
but that has now been revised downward to 135 and 130.
 
The latest prediction has solar flux at 105 on May 23 to 26, 100 on
May 27 to 29, 110 on May 30, 120 on May 31 through June 3, 125 on
June 4 and 5, 130 on June 6 and 7, 135 on June 8 to 10, 130 on June
11 and 12 and 125 on June 13 to 15. Flux values then drop down to
105 on June 22 to 24.
 
Predicted planetary A index is 8 on May 23, 5 on May 24 and 25, 8 on
May 26, 5 on May 27 through June 3, 12 on June 4, 8 on June 5 to 8,
and 5 on June 9 to 16.

F.K. Janda, OK1HH sends us his weekly geomagnetic outlook. He
expects quiet to unsettled activity May 23, mostly quiet May 24,
quiet May 25, quiet to active May 26, quiet to unsettled May 27,
quiet May 28 and 29, quiet to active May 30 and 31, mostly quiet
June 1, quiet June 2, quiet to active June 3, active to disturbed
June 4, quiet to active June 5, active to disturbed June 6, quiet to
unsettled June 7, quiet June 8 and 9, mostly quiet June 10, quiet to
unsettled June 11, quiet June 12, mostly quiet June 13, quiet June
14 to 16, and quiet to active June 17 and 18.
 
Lawrence, GJ3RAX of Jersey (not New Jersey, but the old Jersey, the
Isle of Jersey in the United Kingdom) says "Not much to report from
here this time. There have been several more Es openings on 6 meters
during the last week but mostly to places within Europe that are
already on my list for this year although I have added a few new
grid squares to my annual table in the VHF group. Most QSOs have
been with Italy and Spain."

"Now hoping to be on at the right time to catch openings again on 4
meters and eventually on 2 meters."

Lawrence (who doesn't seem to use a last name) mentioned the 4-meter
band, which many may be unfamiliar with. Four meters is used in only
a few countries, and the common allocation is 70-70.5 MHz.
Apparently Great Britain at one time also had a 5 meter amateur band
at 56 MHz.  Perhaps 70 MHz will be allocated for radio amateurs in
the United States some day. For more information see
http://en.wikipedia.org/wiki/4-meter_band , http://www.70mhz.org/
and http://g1efu.webs.com/4meters.htm .
 
Pete, K2ARM of Fort Edward, New York (about 50 miles north of
Albany) reported on May 20, "We have had a few openings on 6 meters
in May but not for long. Even though the big guns have been working
into Europe and South America, I haven't heard much on my dipole.
But on May 11 I worked PV8ADI, LU4FPZ, LW3EX, and CX7CO on 6 meter
CW plus a few states. I only run 40 watts to a dipole and only use
CW."
 
"On May 18 the band opened up around 1300 UTC and stayed open until
0000 UTC. Signals were 30 to 50 over S9 from the Midwest at times
and around 2210 UTC I worked WN6K and AI6O in California. Soon
after, XE2CQ came pounding in but I could not get through. It looks
like even though 6 meter sporadic E started out late, it may be
better than last year."
 
On May 22 Pete wrote, "6 meters was open again last night until late
in the evening. There were beacons from everywhere but not many
stations on. My dipole is only up 20 feet and I am in a valley,
great for DX!!!"
 
Thanks, Pete.
 
For anyone considering six meters, remember that a half-wave dipole
is only about 9 feet plus 3 inches long for the low end of that
band.
 
Scott Bidstrup, TI3/W7RI wrote on May 21:
 
"Those were interesting responses you posted last week to my inquiry
about the possibility of VHF propagation as a result of lightning
sprites. They seem to confirm what I conjectured. I think
investigation of this could be a good subject for someone's Ph.D.
thesis."
 
"The declining solar activity has taken its toll down here on 6
meter propagation. There have been almost no openings the last
couple of weeks, and what there have been, were short and rather
sparse. I logged the YV4AB beacon about a week ago, as did YS1AG
yesterday, the east-west path in both cases demonstrating that
sporadic E does exist at these latitudes, though it is much rarer
and sparser than in the United States or Europe."
 
"Meanwhile, the afternoon transequatorial openings from the States
into South America have been continuing almost daily, and even
though the paths go right over our heads here in Central America,
we're still hearing nothing at all here on the ground. TI5XP has
built a high gain beam for six, on a 42 foot boom, and even with it,
he's been hearing nothing. I am starting to see some evening TEP in
Europe on the maps in the last few days; since that is a different
mode, perhaps it will yield us some propagation. We can only hope."
 
Scott sent along this interesting article, another one mentioning
that huge July 2012 solar flare:
 
http://news.discovery.com/space/huge-solar-flare-reveals-explosive-magnetic-trigger-140521.htm

This weekend is the CQ World Wide WPX CW Contest. The SSB weekend
was in March. See http://www.cqwpx.com/ for further information.

Summer solstice is only four weeks away, at 1051 UTC on Saturday,
June 21.
 
To illustrate what summer propagation may be like compared to
Spring, I ran some arbitrary numbers on W6ELprop for a path from
Cleveland, Ohio to Germany with a sunspot number of 130, on the
twenty-third of March (near the equinox), April, May (today) and
June (near the solstice, all on the twenty-third of each month.
 
Examining 15 meters, in March we see the path begin to heat up
around 1200 UTC, becoming quite promising at 1400 UTC with a
relative signal level of 47, changing to 48 at 1700 UTC, 50 at 1900
UTC, 51 at 2000 UTC, 52 at 2100 UTC and 53 at 2200 UTC. Then
prospects begin to fade until the path is unlikely to support
propagation by 0100 UTC.
 
For the same path on April 23 we see 15 meters begin to open at 1230
UTC, with a relative signal level rating of 45 but with chances of
an opening increasing at 1830 UTC with a signal rating of 47. The
signal increases to 50 at 2030 UTC, but the path begins to fade
between 2200-0030 UTC.
 
For today (although recent sunspot numbers are not as high) we don't
see much chance of propagation until 1430 UTC with signal ratings
gradually increasing from 43 to 45 at 1800, 47 at 1930, 50 at 2130,
52 at 2300, then fading after 0000 UTC.
 
A month from now we see poor prospects around the clock, with a
D-rating (less than 25 percent chance) from 0430-0800 UTC, and
C-rating (25-50 percent chance of opening) 0830-0400 UTC.  So the
summertime propagation on 15 meters is much poorer than at the
spring equinox.
 
If we look at much higher numbers, such as a sunspot number of 250
instead of 130, we do see improvement, with several periods of B
(50-75 percent) ratings.
 
K9LA has the W6ELprop software (for Windows) as well as tutorials
available at his site, http://k9la.us/. If you want to guess what
propagation might be like next month from your Field Day QTH to
various targets around the United States, you could download the
program and perhaps make an average of predicted solar flux over the
weekend and several days prior, and plug that number into the
program instead of sunspot number. See a daily update of predicted
solar flux and planetary A index for the next 45 days at
http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html .
 
Let's hope for the best, an extension of this current solar cycle
peak, rather than weakening and decline in solar activity.

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. More good
information and tutorials on propagation are at http://k9la.us/.
 
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 May 15 through 21 were 130, 136, 146, 138, 130,
126, and 100, with a mean of 129.4. 10.7 cm flux was 152.1, 138.7,
133.5, 127.5, 116.9, 117.2, and 113.9, with a mean of 128.5.
Estimated planetary A indices were 5, 5, 4, 5, 4, 4, and 3, with a
mean of 4.3.  Estimated mid-latitude A indices were 5, 6, 4, 5, 4,
4, and 3, with a mean of 4.4.
NNNN
/EX