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ARRL Propagation Bulletin ARLP030 (2015)

SB PROP @ ARL $ARLP030
ARLP030 Propagation de K7RA

ZCZC AP30
QST de W1AW  
Propagation Forecast Bulletin 30  ARLP030
From Tad Cook, K7RA
Seattle, WA  July 24, 2015
To all radio amateurs 

SB PROP ARL ARLP030
ARLP030 Propagation de K7RA

All daily sunspot numbers dipped into the double digits last week,
with the average declining from 73.7 to 43.4. This compares the
latest July 16 to 22 period against the previous seven days.
 
Over the same periods, average daily solar flux went from 114.8 to
95.1.
 
Geomagnetic indices were mostly quiet, with average daily planetary
A index going from 13.7 to 6.1 and average mid-latitude A index
declining from 12.3 to 8.1.
 
At 0749 UTC on July 23 the Australian Space Forecast Center posted a
geomagnetic disturbance warning: "A sustained period of southward
IMF is resulting in mildly elevated levels of geomagnetic activity,
particularly at high latitude regions. Further mildly elevated
levels of geomagnetic activity are possible during the remainder of
23 July."
 
And indeed the planetary A index for the day was 23, with planetary
K index reaching 3, 4, 5 and 3 over the first four 3-hour readings.
The high latitude college A index was 33, with the first K index
readings at 3, 4, 7, and 4.
 
Predicted solar flux is 90 on July 24, 95 on July 25, 100 on July 26
and 27, 105 on July 28 to 30, 110 on July 31, 115 on August 1 to 4,
110 and 105 on August 5 and 6, 100 on August 7 to 9, then 95 on
August 10 to 13, finally dipping to 85 by August 15, then peaking
(weakly) at 115 on August 28 to 31.
 
Predicted planetary A index is 15, 12, 8 and 5 on July 24 to 27,
then 10, 8, 5 and 18 on July 28 to 31, then 25 and 12 on August 1
and 2, 5 on August 3 to 5, then 20, 25, 15, 10, and 8 on August 6 to
10, 5 on August 11 to 15, 10 on August 16, 5 on August 17 and 18,
then 15 and 10 on August 19 and 20, 5 on August 21 to 26, then 18,
25 and 12 on August 27 to 29.
 
NOAA says the geomagnetic field is expected to be quiet to active on
July 24 and 25 and quiet to unsettled on July 26.
 
OK1HH sees the geomagnetic field as quiet to active on July 24,
quiet to unsettled July 25, mostly quiet July 26, quiet July 27,
mostly quiet July 28, quiet July 29, quiet to active July 30, active
to disturbed July 31 through August 1, quiet to active August 2,
mostly quiet August 3, quiet on August 4, mostly quiet August 5,
quiet to active August 6, active to disturbed August 7 and 8, quiet
to active August 9, quiet to unsettled August 10, mostly quiet
August 11, quiet August 12 to 14, mostly quiet August 15, quiet to
unsettled August 16, mostly quiet August 17 and quiet on August 18.
 
He sees increases in solar wind on July 24 to 26, August 1 to 5, and
8 to 10.  He sees uncertainty though for any predictions on July 26,
August 1 to 5, August 8, August 17 and 18.
 
Here is an interesting article about how the far side views of the
sun from the STEREO mission are disrupted because the satellite
transmissions back to earth are blocked by the sun. But here the
Curiosity rover on Mars fills in.
 
http://www.space.com/30012-mars-rover-curiosity-sunspots-far-side.html
 
Check this table of predicted International Sunspot Numbers:
http://1.usa.gov/1HOVlDP
 
or:
 
ftp://ftp.ngdc.noaa.gov/STP/space-weather/solar-data/solar-indices/sunspot-numbers/predicted/table_international-sunspot-numbers_monthly-predicted.txt
 
Note the next minimum is predicted roughly for July 2019, just four
years from now, and unlike the last minima, there is some sunspot
activity!  Let's hope this is correct. Compare those numbers with
all of 2009 in the same table. These are smoothed sunspot numbers,
and someone out there is optimistic.
 
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/.
 
Archives of the NOAA/USAF daily 45 day forecast for solar flux and
planetary A index are in downloadable spreadsheet format at
http://bit.ly/1IBXtnG and http://bit.ly/1KQGbRm .
 
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 http://arrl.org/propagation.
 
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.
 
Sunspot numbers for July 16 through 22 were 55, 40, 52, 46, 39, 37,
and 35, with a mean of 43.4.  10.7 cm flux was 99.6, 97.4, 96, 99.4,
93.2, 91, and 89, with a mean of 95.1. Estimated planetary A indices
were 8, 5, 4, 3, 5, 10, and 8, with a mean of 6.1. Estimated
mid-latitude A indices were 15, 7, 4, 3, 7, 12, and 9, with a mean
of 8.1.
NNNN
/EX