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The following is the weekly propagation bulletin from W1AW / ARRL (posting on 20160722 22:17 UTC):
QST de W1AW
Propagation Forecast Bulletin 30 ARLP030
>From Tad Cook, K7RA
Seattle, WA July 22, 2016
To all radio amateurs
SB PROP ARL ARLP030
ARLP030 Propagation de K7RA
All solar indices rose over the past week, and geomagnetic
indicators were lower.
Average daily solar flux rose from the previous seven days at 52.6
to 58.1, and average daily sunspot numbers rose from 91.6 to 103.6.
Average daily planetary A index went from 15.7 to 10.6 and average
daily mid-latitude A index changed from 14.1 to 11.1.
The latest (Thursday night) predictions for solar flux show 100 on
July 22 to 23, 95 and 90 on July 24 and 25, 85 on July 26 and 27, 80
and 75 on July 28 and 29, 70 on July 30 to August 4, 80 and 95 on
August 5 and 6, 105 on August 7 to 16, 100 on August 17 and 18, then
95, 90, 80 and 75 on August 19 to 22, and 70 on August 23 to 31. For
the next few days following the end of August the prediction shows a
sharp rise in solar flux from 70 to 105.
Predicted planetary A index levels are at 10, 8, 12, 8 and 5 on July
22 to 26, 8 on July 27 to 31, 5 on August 1 and 2, 20 on August 3
and 4, 15 on August 5, 10 on August 6 and 7, then 20, 8, 12, 10 and
8 on August 8 to 12, 5 on August 13 and 14, then 8, 12 and 15 on
August 15 to 17, 10 on August 18 and 19, 8 on August 20, 5 on August
21 to 23, then 8 and 9 on August 24 and 25, 8 on August 26 and 27, 5
on August 28 and 29, and 20 on August 30 and 31.
At 2341 UTC on July 19 the Australian Space Forecast Centre issued a
geomagnetic disturbance warning:
A shock wave signature was detected in the solar wind on 19 July at
2300 UTC. A geomagnetic sudden impulse is expected, followed by
increased geomagnetic activity up to minor storm levels.
INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL MASS EJECTION
FROM 20-22 JULY 2016
GEOMAGNETIC ACTIVITY FORECAST
20 Jul: Active to Minor Storm
21 Jul: Active
22 Jul: Unsettled to Active
The Geomagnetic activity forecast for the period July 22 to August
16, 2016 from OK1HH follows.
Geomagnetic field will be:
Quiet on August 1, 13 and 14
Mostly quiet on July 25, 28 and 29, August 11 and 12
Quiet to unsettled on July 26, August 7, 16
Quiet to active on July 22, 27, 30 and 31, August 2, 5 and 6, 8 and
9, 10, 15
Active to disturbed on July 23 or 24, August 3 and 4
Increased solar wind from coronal holes is expected on July 27 and
28, July 30 through August 2, and August 7 and 8.
Bob Sherman, K2SJP of Lutz, Florida noted a 10 meter opening on July
11 when he worked many West Coast stations. The next day on 10
meters he worked a station in Kuwait.
Dave Grubbs, N4EF of Apopka, Florida wrote, 'You wrote in
Propagation Forecast Bulletin 29 that any perking up of propagation
would be unpredictable and temporary -- how right you were.
There was a fleeting 30 minute night-time opening from my central
Florida QTH on 30 meters on July 17. The band was dead at 0745 UTC
(3:45 AM EDT) and there were no replies to my CQs on 10112 KHz.
About 15 minutes later, I copied a GI4 station, JA1KIH, and CO8LY at
the same time within 500 Hz of each other.
The GI4 was engaged in a QSO and the JA1 and CO8 were calling CQ
simultaneously nearly on top of each other. I worked Taka, JA1KIH
with a 559 report each way which was thrilling since I was running
100 watts to a dipole 15 feet high in my attic. The Cuban station
was loud enough to cause QRM to my QSO yet Eduardo is only 700 miles
(1113 km) from me and had a steady signal. Was this a very short
skywave hop or a long groundwave signal from Cuba?
My Florida QTH and Taka's QTH appear to be in the gray line at the
same time, but this brief opening occurred at 0800 UTC which was 2
hours 39 minutes before my sunrise and hence not attributable to
terminator/gray line propagation. The band was void of CW again
until well past sunrise.'
Check out Dave's interesting post and images on his call sign listing
on QRZ.com: https://www.qrz.com/db/n4ef
Actually what I was trying to say in last week's bulletin was any
increase in solar activity would be temporary.
Ted Leaf, K6HI in Kona, Hawaii asked 'What is the correlation
between sunspot numbers and solar flux?'
There is a high correlation between sunspot numbers and solar flux,
assuming you are looking at smoothed values for each. Smoothed
sunspot numbers average a year of data, so the actual value lags
behind the latest data by six months.
Here is an article by K9LA on the topic:
http://k9la.us/Correlation_Between_Solar_Flux_and_Sunspot_Number.pdf
Determining the sunspot number is somewhat subjective, and it is
also tough to do when the sky is overcast. But the 10.7 cm solar
flux is completely objective. It involves pointing a parabolic dish
at the sun at local noon, then measuring the radiation at 2.8 GHz.
This paper notes a correlation which also incorporates solar
irradiance:
https://arxiv.org/ftp/arxiv/papers/0804/0804.1941.pdf
Interesting article about our sun in a recent issue of The Atlantic:
http://www.theatlantic.com/science/archive/2016/07/staring-at-the-sun/491939/
Jeff, N8II in West Virginia reported on July 16:
'Some of your readers should have experienced 2M Es on Friday
evening (July 15) around 0000-0100Z. DXMAPS.com showed estimated
MUF's as high as over 180 MHz over grids in eastern OH, NW PA, and
western NY. I worked as close as EN91 on 6M and many stations
centered around Chicago extending eastward including IN and OH both
in EM79. NP4A was also worked and the evening before I logged 3 or 4
Puerto Rico hams on 6M phone and CW all in FK68.
Despite the improved SFI, 15 M remains very dead sounding, but I
have not had time to listen much since the IARU contest last
Saturday July 9 when EU signals were mostly weak and from south EU,
but I did work around 50 of them along with some Es into New England
and quite a few Caribbean and SA stations.'
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 July 14 through 20 were 54, 73, 47, 51, 68, 58,
and 56, with a mean of 58.1. 10.7 cm flux was 95.1, 102.1, 106.6,
105.2, 107.1, 100.8, and 108, with a mean of 103.6. Estimated
planetary A indices were 12, 11, 8, 6, 4, 10, and 23, with a mean of
10.6. Estimated mid-latitude A indices were 16, 10, 8, 10, 4, 11,
and 19 with a mean of 11.1.
Get the space weather and radio propagation self-study course, today. Visit http://nw7us.us/swc for the latest sale and for more information!
Check out the stunning view of our Sun in action, as seen during the last five years with the Solar Dynamics Observatory (SDO):
https://www.youtube.com/watch?v=zXN-MdoGM9g
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