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ARRL Propagation Bulletin ARLP029 (2015)

ARLP029 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 29  ARLP029
From Tad Cook, K7RA
Seattle, WA  July 17, 2015
To all radio amateurs 

ARLP029 Propagation de K7RA

Average daily sunspot numbers dropped from 109.1 on July 2 to 8 to
73.7 in the past week, July 9 to 15. Average daily solar flux
dropped from 123.2 to 114.8 over the same two periods.  Geomagnetic
indices were more active, with average daily planetary A index
increasing from 10 to 13.7, and average mid-latitude A index going
from 8.9 to 12.3.
The geomagnetic field was active on July 11 when the mid-latitude A
index, the high latitude college A index, and planetary A index were
20, 44 and 23. Activity was greater on July 13 when the three
indices were 22, 45 and 32.
The July 11 activity was a G1 class geomagnetic storm caused by a
high-speed solar wind stream, and similar events caused the July 13
activity. Currently there is very little chance of solar flares or
geomagnetic storms over the next few days.
Predicted planetary A index is 8 on July 17 and 18, 10 on July 19
and 20, 5 on July 21 to 30, 18 on July 31, 25 on August 1, and 12 on
August 2. On August 3 to 5 the planetary A index is predicted at 5,
then 20 and 25 on August 6 and 7, and 8 on August 8 to 10. On August
11 and beyond the planetary A index prediction is 5.
Predicted solar flux is 100 on July 17 to 19, 95 on July 20 and 21,
100 on July 22 and 23, 105 on July 24, 110 on July 25, 115 on July
26, 120 on July 27 to 31, and 115 on August 1 to 4. Solar flux is
expected to rise to 120 again after August 22.
Recently there have been only a few new sunspot groups, one each on
July 7, 8, 10 and 12 and two on July 16.
F. K. Janda, OK1HH predicts the geomagnetic field will be quiet to
unsettled July 17 to 18, quiet to active July 19, quiet to unsettled
July 20 and 21, quiet to active July 22, mostly quiet July 23 and
24, quiet July 25 and 26, mostly quiet July 27, quiet July 28 and
29, quiet to active July 30, active to disturbed July 31 through
August 1, quiet to active August 2, mostly quiet August 3, quiet
August 4, mostly quiet August 5, quiet to active August 6, quiet to
unsettled August 7, active to disturbed August 8, quiet to unsettled
August 9, and mostly quiet August 10 and 11.
OK1HH expects increases in solar wind on July 19 to 26, August 1 to
5, August 8 and August 9 and 10.  He believes there is a lower
probability of geomagnetic activity increases on July 19, July 26,
August 1 to 5, and August 8.
David Moore sent a link to an article about combined images from
several solar telescopes at: .
Scott Bidstrup, TI3/W7RI sends this report from Costa Rica:
"Propagation here in the low latitudes seems to be starting to
settle into its declining solar-cycle funk. 10 meter and 12 meter
openings are becoming less common, and 15 meter through 20 meter
signals seem to be rather lackadaisical, too. The only bright spot
for us is that the mid-day blackout is less intense, with signals no
longer fading out completely around noon as we are used to, though
they are unusably weak. Rare are the days now that the bands seem to
be really lively, with strong signals. It would all be rather
depressing, were it not for the improving DX conditions on 80 meters
and 40 meters. Even during the peak of the northern summer, our
noisiest time of the year here, we're occasionally getting gray-line
conditions that enable VKs, ZLs YBs and occasionally JAs to be
worked here on 80 meters, in spite of the high noise levels.  Jay,
HP3AK, reports that this is the noisiest midyear season he can
remember here, yet he has nevertheless had some success working the
western Pacific on 75 meters. But he has been spending much of his
time on 40 meters just to hear signals strong enough to make it over
the noise. He recently installed a Waller Flag, and that has helped
significantly on both bands, he reports, but it is still no panacea.
I have seen some references in the literature to the rising altitude
of the tropopause in the tropics due to global warming, resulting in
more powerful thunderstorms with higher cloud-tops - and therefore
possibly more powerful lightning. That, possibly along with El Nino,
could account for the clearly increasing 80/40 meter noise levels
here this year, especially on 40 meters, which is now approaching
the noise levels normally seen only on 80 meters. On the worst days,
they have exceeded S9+40dB, even on 40 meters! As I write this at 5
PM, the noise level on 80 meters is currently S9+10 and on 40 is
about the same. I can't ever recall noise levels that high here on
40 in the past. Fortunately, they drop fast shortly after sunrise,
and don't return until about an hour before sunset, giving us a bit
of a break early morning and late afternoon when propagation is
still possible through the D layer.
The fellas bemoaning the crummy Es season on 6 meters in the States
are hardly alone; it's been just as anemic here, even more so.
Normally by now, our TEP season into South America would be well
underway and we'd have enjoyed several Es openings into the Windward
Islands and northern South America, but not so this year. We haven't
had a single TEP opening yet, and we've had a few weak and short Es
openings here, one into KP4, the others into YV, but nothing to
write home about, and no DX worth coming running into the shack for.
Nothing into the States either, other than a single contact into
Florida reported to me by Michael, TI5XP. In the last month, I've
only gotten a single 6 meter contact in my log, and that was with a
YV I'd already worked many times before. It's been a heck of a DX
drought and we're getting desperate!"
Scott mentioned the Waller Flag, which is a low band receiving
antenna that has good noise rejection. See , ,
, and .
Thanks to the ARRL Contest Update for this piece on 6 meter
For more information concerning radio propagation, see the ARRL
Technical Information Service at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are at
Archives of the NOAA/USAF daily 45 day forecast for solar flux and
planetary A index are in downloadable spreadsheet format at and .
Click on "Download this file" to download the archive and ignore the
security warning about file format. Pop-up blockers may suppress
download. I've had better luck with Firefox than IE.
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for July 9 through 15 were 120, 124, 91, 59, 44, 39,
and 39, with a mean of 73.7. 10.7 cm flux was 121.9, 129, 120.2,
116, 110.1, 105.2, and 101, with a mean of 114.8.  Estimated
planetary A indices were 6, 10, 23, 11, 32, 7, and 7, with a mean of
13.7. Estimated mid-latitude A indices were 7, 11, 20, 12, 22, 8,
and 6, with a mean of 12.3.


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