[South Florida DX Association] ARLP018 Propagation de K7RA

[Bill Marx]

ZCZC AP18
> QST de W1AW  
> Propagation Forecast Bulletin 18  ARLP018
> From Tad Cook, K7RA
> Seattle, WA  May 6, 2005
> To all radio amateurs 
> 
> SB PROP ARL ARLP018
> ARLP018 Propagation de K7RA
> 
> NASA Science News carries a story titled "Solar Myth," about the
> fact that there is still solar activity toward the bottom of the
> sunspot cycle. The article gives examples of x-ray flares at the
> bottom of recent cycles and shows that the sun is anything but
> quiet. The peak and the bottom of the sunspot cycle are only really
> known after the fact, when we can look back on a graph showing a
> moving average over many months. This is when the graph appears
> smooth, and you can clearly see tops and bottoms. Otherwise there is
> a great deal of daily variation.
> 
> Read the article on the Science at NASA site at,
> http://science.nasa.gov/headlines/y2005/05may_solarmyth.htm?list164615.
> 
> Over the past week sunspot numbers increased, recovering from the
> days of no visible sunspots. Average daily sunspot numbers rose 35
> points to 60.9, and average daily solar flux rose nearly 24 points
> to 107.7
> 
> A new month began last weekend, and we can now examine the April
> averages and compare them to previous months.
> 
> The monthly average of the daily sunspot number for November 2004
> through April 2005 was 70.5, 34.7, 52, 45.4, 41 and 41.5. The
> monthly average of the daily solar flux over the same months was
> 113.7, 95, 102.3, 97.2, 89.9 and 85.9. Whenever we examine monthly
> or quarterly averages we see the decline of the solar cycle quite
> clearly.
> 
> Currently solar flux is expected to remain above 100 for the next
> couple of days, then decline to below 90 after May 12. Geomagnetic
> conditions should remain quiet this weekend, then become unsettled
> to active May 9-11. The predicted planetary A index for May 6-13 is
> 10, 5, 10, 25, 20, 15, 12 and 8.
> 
> This week I received several messages asking "What do these numbers
> mean?" In a very basic sense, HF operators would love to see lots of
> sunspots (high sunspot numbers and probably high solar flux) without
> any geomagnetic disturbance, which would be indicated with a low A
> and K index. But definitely check out the advice toward the end of
> each bulletin, in the next to last paragraph.
> 
> You can also use W6ELprop, free from http://www.qsl.net/w6elprop/ to
> figure your own propagation paths for various bands and times of day
> to anywhere else in the world. Instead of solar flux, use an average
> of several days sunspot numbers with W6ELprop. You can get those
> recent daily numbers from
> http://www.sec.noaa.gov/ftpdir/indices/DSD.txt . The daily sunspot
> number is in the column marked "SESC Sunspot Number."
> 
> 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 28 through May 4 were 71, 46, 53, 61, 55,
> 79 and 61 with a mean of 60.9. 10.7 cm flux was 98, 105, 106.4,
> 111.6, 112.2, 112.3 and 108.7, with a mean of 107.7. Estimated
> planetary A indices were 4, 12, 21, 26, 7, 10 and 7 with a mean of
> 12.4. Estimated mid-latitude A indices were 1, 8, 13, 14, 6, 6 and
> 4, with a mean of 7.4.
> NNNN
> /EX
> 
>