[South Florida DX Association] ARLP017 Propagation de K7RA

[Bill Marx]

 ZCZC AP17
> QST de W1AW  
> Propagation Forecast Bulletin 17  ARLP017
> From Tad Cook, K7RA
> Seattle, WA  April 29, 2005
> To all radio amateurs 
> 
> SB PROP ARL ARLP017
> ARLP017 Propagation de K7RA
> 
> Solar flux and sunspot numbers continue their lull, although again
> this week their relative positions see-sawed. For last week's
> bulletin of April 22 (ARLP016), we reported average daily sunspot
> numbers up a little, and average daily solar flux down a bit. This
> change was noted when the numbers were compared to the data in the
> April 15 bulletin (ARLP015). This week the daily sunspot number on
> average dropped 25 points to 25.9, and the average daily solar flux
> increased a little over two points to 84. Nothing significant about
> any of this, which is common behavior as the solar cycle continues
> to decline.
> 
> This week on Sunday, April 24 the earth-facing sun was spotless, and
> the sunspot number was 0. But the next day a new sunspot appeared,
> number 756, and it is a big one. The spot is growing quickly, and
> the resulting sunspot numbers for April 26-28 were 20, 45 and 71.
> Solar flux is heading toward 100. Predicted solar flux values for
> this weekend, April 29-May 1 are 103 on all days. Flux values should
> rise above 105 by Monday, May 2.
> 
> Geomagnetic conditions have been nice and quiet, but this could
> change over the next week. The predicted planetary A index for April
> 29 through May 3 is 8, 8, 20, 40 and 15. A planetary A index of 40
> indicates a major geomagnetic storm, which is expected from the
> reappearance of a recurring coronal hole and associated high
> velocity wind stream.
> 
> The predicted smoothed sunspot number drops in May from 22 to 19.
> It will continue to decline, with the predicted smoothed sunspot
> number at 10 for the end of 2005 and 5 for the end of 2006, the
> predicted bottom of the solar cycle. In 2007 solar activity should
> rebound, and around the end of that year the smoothed sunspot number
> should be back to where it is now, 18 for November and 21 for
> December 2007. In 2008, based on the behavior of past solar cycles,
> sunspots should make a strong return. That's only three years from
> now.
> 
> Robert Wilson, AL7KK wrote to say he worked for Voice of America and
> planned medium wave AM broadcasts that were around the 160 meter
> wavelength. He said that in 1989 he was using some propagation
> software that worked fine on 160 meters outside of the auroral zone.
> I've asked him to give us more detail, as the propagation programs
> I've used don't work below 3 MHz. I hope to have more information
> soon.
> 
> David Moore sent us a fascinating article from SpaceRef.com about
> the structure of coronal holes and the associated solar wind. The
> article talks about observations published in the April 22 edition
> of Science. You can read the SpaceRef article at
> http://www.spaceref.com/news/viewpr.html?pid=16721 .
> 
> If you would like to comment or have a tip, email the author at,
> k7ra at arrl.net.
> 
> For more information concerning radio propagation and an explanation
> of the numbers used in this bulletin see the ARRL Technical
> Information Service propagation page at,
> http://www.arrl.org/tis/info/propagation.html. An archive of past
> bulletins is found at http://www.arrl.org/w1aw/prop/ .
> 
> Sunspot numbers for April 21 through 27 were 22, 34, 35, 0, 25, 20
> and 45 with a mean of 25.9. 10.7 cm flux was 77.1, 77.2, 79.3, 82.3,
> 86, 90.9 and 95.3, with a mean of 84. Estimated planetary A indices
> were 4, 9, 6, 10, 11, 5 and 4 with a mean of 7. Estimated
> mid-latitude A indices were 2, 7, 5, 5, 9, 2 and 1, with a mean of
> 4.4.
> NNNN
> /EX
> 
>