[SFDXA] ARLP037 Propagation de K7RA

[Bill]

> SB PROP @ ARL $ARLP037
> ARLP037 Propagation de K7RA
> 
> ZCZC AP37
> QST de W1AW  
> Propagation Forecast Bulletin 37  ARLP037
> From Tad Cook, K7RA
> Seattle, WA  September 11, 2015
> To all radio amateurs 
> 
> SB PROP ARL ARLP037
> ARLP037 Propagation de K7RA
> 
> The Australian Space Forecast Centre issued a Geomagnetic
> Disturbance Warning at 0132 UTC on September 8. They wrote, "The
> effect of a high speed solar wind stream from a coronal hole is
> keeping geomagnetic activity enhanced.
> 
> "Geomagnetic activity is expected to remain mostly enhanced to
> Active levels on 8 September with the possibility of some minor
> storm periods."
> 
> If you look at ftp://ftp.swpc.noaa.gov/pub/indices/DGD.txt you can
> see the effect, which is high numbers indicating geomagnetic
> instability. What does this mean for performance on the air? For HF
> it can mean higher absorption rates (meaning radio waves may be
> absorbed more than they are reflected) but it can mean some
> interesting propagation modes may occur on VHF.
> 
> The Australian Space Forecast Center issued another geomagnetic
> disturbance warning at 0017 UTC on September 11: "A high speed solar
> wind stream from a coronal hole is expected to arrive late on 11
> September. This may result in the geomagnetic activity rising to
> Active to Minor Storm levels. This rise in geomagnetic activity is
> expected to continue on 12 September."
> 
> Frank Donovan, W3LPL sent a fascinating article about a rejuvenation
> in solar magnetic strength toward the end of 2014, and an alternate
> view from the recent news stories about a long term dearth of
> sunspots. Instead, they propose that Cycle 25 (the next one) may be
> similar to Cycle 24 (the one we are now in).
> 
> Read it at,
> http://aasnova.org/2015/09/02/witnessing-solar-rejuvenation/ .
> 
> Weak solar activity continued this week. The average daily sunspot
> number for September 3-9 was only 37.3, down 11 points from the
> previous seven days. Average daily solar flux was 85.3, compare to
> 97 for the previous week.
> 
> Geomagnetic activity was strong, with average planetary A index up
> from 19.4 to 27.1. The most active day was Wednesday, September 9
> when the planetary A index was 59.
> 
> The latest solar flux prediction from USAF/NOAA has readings of 85,
> 90 and 100 on September 10-12, 105 on September 13-14, 110 on
> September 15-17, 115 on September 18-22, then 110, 105, 100 and 95
> on September 23-26, 90 on September 27 to October 1, and 85 on
> October 2-7. Flux values then rise to 115 on October 15-19.
> 
> Predicted planetary A index is 28, 16 and 27 on September 10-12,
> then 16, 10 and 8 on September 13-15, 5 on September 16-17, then 8,
> 20 and 10 on September 18-20, 5 on September 21-23, then 15 and 10
> on September 24-25, 5 on September 26-29, then 8 and 18 on September
> 30 through October 1, 12 on October 2-4, 8 on October 5, then 5 on
> October 6-7, then 8, 12 and 8 on October 8-10, and 10 on October
> 11-13.
> 
> Both the solar flux and planetary A index predictions are from
> September 9. The new forecast appears every day after 2100 UTC, but
> so far early on September 11 the September 10 forecast is not
> available. You can catch up by checking,
> ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ .
> 
> We do have a geomagnetic forecast from OK1MGW who predicts quiet to
> active conditions September 11-13, (with September 11 conditions
> perhaps at active to disturbed levels), quiet to unsettled September
> 14, quiet to active September 15-16 (with September 15 conditions
> possibly at active to disturbed levels), quiet to unsettled
> September 17-18, active to disturbed conditions September 19, then
> mostly quiet on September 20-21, quiet to active September 22,
> active to disturbed September 23-24, quiet to unsettled September
> 25, quiet on September 26-28, mostly quiet September 29, and quiet
> to unsettled September 30. He expects increases of solar wind on
> September 11-13, 15-16, 19, and 22-24.
> 
> Note that the mid-latitude A index for September 8 and 9 listed at
> the end of this bulletin are wild guesses on my part, based on
> tracking with the planetary A index. If you look at
> ftp://ftp.swpc.noaa.gov/pub/indices/DGD.txt you will see there is no
> data for those dates. This is probably because geomagnetic activity
> was strong enough to knock the Fredericksburg and College (for the
> high latitude number) magnetometers out of service.
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at, k7ra at arrl.net.
> 
> For more information concerning radio propagation, see the ARRL
> Technical Information Service web page 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/.
> 
> My own 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/1VOqf9B and http://bit.ly/1DcpaC5 .
> 
> 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 Internet Explorer.
> 
> 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 September 3 through 9 were 27, 36, 24, 38, 47,
> 40, and 49, with a mean of 37.3. 10.7 cm flux was 86.5, 89.9, 85.4,
> 85.6, 83.7, 83.5, and 82.3, with a mean of 85.3. Estimated planetary
> A indices were 9, 20, 13, 14, 46, 29, and 59, with a mean of 27.1.
> Estimated mid-latitude A indices were 9, 18, 10, 12, 27, 24, and 31,
> with a mean of 18.7.
> NNNN
> /EX