[SFDXA] ARLP037 Propagation de K7RA

[WILLIAM MARX]

> 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 10, 2021
> To all radio amateurs 
> 
> SB PROP ARL ARLP037
> ARLP037 Propagation de K7RA
> 
> Sunspot activity increased dramatically this week.
> 
> Sunspot numbers (when looking at only the activity during our
> Thursday through Wednesday reporting week) peaked at 87 on
> Wednesday, September 8 and the day before, solar flux peaked at
> 101.2.
> 
> Average daily sunspot numbers rose 14, to 64.6, while average daily
> solar flux increased from 88 to 92.9.  New sunspots appeared on
> September 2, again on September 3, and three more new sunspot groups
> arrived on September 4.  Another new one appeared on September 8,
> and on that day the total sunspot area was 1000 micro-hemispheres.
> 
> On September 9 I was shocked to see the daily sunspot number at 124
> and total sunspot area hit 1030 micro-hemispheres.  I'm not certain,
> but it looks like we have not seen activity like this in nearly six
> years, when the daily sunspot number was 125 on September 29, 2015.
> 
> We saw similar large total sunspot area numbers last November 25 and
> 26, 1180 and 1020 micro-hemispheres.  Sunspot numbers were 40 and 43
> on those days, but a few days later on November 29 the sunspot
> number rose to 84.
> 
> Both the daily planetary and middle latitude A index reached a high
> of 14 on September 8.  The averages were 7 and 7.7, down from 9.6
> and 10.7 in last week's planetary and middle latitude readings.
> 
> Predicted solar flux seems quite promising, at 100 on September 10
> and 11, 98 on September 12 and 13, 95 on September 14 to 17, 85 on
> September 18, 88 on September 19 to 23, 90 on September 24 to 28, 88
> on September 29 through October 1, 86 on October 2, 90 on October 3
> to 6, 92 and 90 on October 7 and 8, and 85 on October 9 to 15.  Flux
> values are expected to rise to 90 again after October 20.
> 
> Predicted planetary A index is 5, 8 and 8 on September 10 to 12, 5
> on September 13 to 20, 8 on September 21, 5 on September 22 through
> October 1, then 8 again on October 2 and 3, and 5 on October 4 to
> 17.
> 
> On Sunday September 5, Spaceweather.com reported ''For most of the
> past three years, the sun has been absolutely blank.  Today the sun
> has six sunspot groups.  They're popping up all over the solar
> disk.''
> 
> ''The sudden profusion of so many sunspots is a sign of strength for
> young Solar Cycle 25.  The solar cycle is actually running ahead of
> schedule.  NOAA and NASA predicted that it will peak in the year
> 2025.  Outbreaks like this one support the idea that Solar Max could
> come a year early.''
> 
> On September 8 Spaceweather.com reported a shortwave blackout over
> the Pacific Rim caused by a CME (Coronal Mass Ejection) on September
> 8 at 1736 UTC.
> 
> Here is Tamitha Skov's recent forecast, although by now it is a bit
> out of date:
> 
> https://youtu.be/EndF67TGlnY
> 
> An interesting article about recent solar activity, but it is
> plagued with many popups:
> 
> https://bit.ly/396UGFf
> 
> Recently in this bulletin we mentioned the US Postal Service issuing
> stamps with solar images.  Here is an article from June which gives
> much more detail on the creation of the stamps:
> https://bit.ly/3yRtlkx
> 
> For more information concerning shortwave radio propagation, see
> http://www.arrl.org/propagation and the ARRL Technical Information
> Service at http://arrl.org/propagation-of-rf-signals.  For an
> explanation of 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/.
> 
> Instructions for starting or ending email distribution of ARRL
> bulletins are at http://arrl.org/bulletins .
> 
> Sunspot numbers for September 2 through 8, 2021 were 33, 33, 68, 66,
> 80, 85, and 87, with a mean of 64.6.  10.7 cm flux was 85.8, 83.8,
> 86.5, 93.3, 99.5, 101.2, and 100.4, with a mean of 92.9.  Estimated
> planetary A indices were 4, 6, 5, 6, 6, 8, and 14, with a mean of 7.
> Middle latitude A index was 3, 6, 5, 8, 8, 10, and 14, with a mean
> of 7.7.
> NNNN
> /EX