[South Florida DX Association] ARLP031 Propagation de K7RA

[Bill Marx]

 SB PROP ARL ARLP031
> ARLP031 Propagation de K7RA
> 
> Last Friday, July 28, a high speed solar wind stream hit earth, and
> created a geomagnetic disturbance that drove the planetary and
> mid-latitude A index up to 29 and 26, respectively.  This actually
> began in the early hours of Friday UTC, which was Thursday afternoon
> and early evening in North America.  Both mid-latitude and planetary
> K index rose to six.  If you noticed some periods of high
> absorption, or when the only propagation seemed to occur north to
> south, that would be why.
> 
> Now we are moving slowly toward the fall equinox, and HF radio
> conditions tend to get better when the hours of light and darkness
> are equal between the northern and southern hemispheres.
> 
> This week we saw the average daily sunspot number rise over five
> points to 20.  We will see little variations like this as the solar
> cycle declines toward its minimum next year.  Solar activity still
> seems too high to be at the bottom though.  A glance at graphs of
> smoothed sunspot numbers shows we are still experiencing more
> sunspots than the minimum back in 1996.  Check the graph at
> http://wm7d.net/hamradio/solar/historical.shtml on the very bottom
> of the page, and http://www.sec.noaa.gov/weekly/pdf/prf1613.pdf on
> page 9.  Further down on page 9, you can see that the prediction for
> the smoothed sunspot number for August 2006 is the same as for
> August of next year, and the minimum is somewhere in between.  That
> means according to this graph, a year from now the new solar cycle
> will be bouncing back from the minimum, and rising past the point
> where we are now.  The smoothed numbers are averaged over many
> months (I think this graph uses a moving six-month average) to help
> us see past the ''noise'' of daily variations.  This graph shows a
> minimum in January 2007, only five months from now, with a smoothed
> sunspot number of five.
> 
> July is over, so we can look at some monthly averages of sunspot
> numbers and solar flux.
> 
> The average daily sunspot numbers for the months July 2005 through
> July 2006 were 68.7, 65.6, 39.2, 13, 32.2, 62.6, 26.7, 5.3, 21.3,
> 55.2, 39.6, 24.4 and 22.6.  Average daily solar flux for the same
> months was 96.5, 92.4 , 91.9, 76.6, 86.3, 90.8, 83.4, 76.5, 75.5,
> 88.9, 80.9, 76.5 and 75.8.
> 
> Over the past week I've been playing with the excellent HF radio
> propagation software, ACE-HF Pro, written by Richard Buckner.  ACE
> is an acronym: Animated Communications Effectiveness, and it was
> originally written for VLF communication with submarines.
> 
> This program is really a treat.  ACE-HF Pro is based on software
> that Buckner wrote for military and commercial clients while at
> Collins Radio, and it uses the VOACAP engine.  He has a new version
> 2.05 out, which is much more Windows-friendly than earlier versions.
> With it, you can produce colorful graphs that make it easy to
> visualize propagation over time and space, and users can even
> animate the results to produce a movie of signal coverage over time.
> Unlike other propagation programs I've used, it also makes 160-meter
> predictions, and attempts to predict sporadic-E skip.
> 
> Tomas Hood, NW7US, who writes the monthly Propagation column for CQ
> Magazine, did some detailed reviews of ACE-HF in the May and July
> issues.  He also has reviews online at http://hfradio.org/ace-hf/ .
> Among the interesting and unusual features is the ability to factor
> antenna radiation patterns into the calculations of propagation
> paths.
> 
> David Mays, W8UI of St. Marys, West Virginia sent some big beacon
> lists for HF and six meters, put together by G3USF.  See them at
> http://www.keele.ac.uk/depts/por/28.htm and
> http://www.keele.ac.uk/depts/por/50.htm.  Also, Bruce Brackin, N5SIX
> of Brandon, Mississippi commented on Larry Godek, W0OGH and his wish
> for a database of 10-meter repeaters searchable by frequency, all
> across North America, rather than lists sorted by state.  This would
> help him identify the location of 10 meter repeaters when they
> appear.  David recommends getting the ARRL TravelPlus CD, then
> exporting the data to a CVS file and sorting it in a spreadsheet
> program.
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at, k7raarrl.net.
> 
> For more information concerning radio propagation, see the ARRL
> Technical Information Service at
> http://www.arrl.org/tis/info/propagation.html. For a detailed
> explanation of the numbers used in this bulletin, see
> http://www.arrl.org/tis/info/k9la-prop.html. An archive of past
> propagation bulletins is at http://www.arrl.org/w1aw/prop/ .
> 
> Sunspot numbers for July 27 through August 2 were 23, 17, 19, 23,
> 25, 11 and 22 with a mean of 20. 10.7 cm flux was 74.4, 72.6, 73,
> 73.9, 72.4, 72.8, and 72.1, with a mean of 73. Estimated planetary A
> indices were 9, 29, 5, 5, 12, 12 and 10 with a mean of 11.7.
> Estimated mid-latitude A indices were 5, 26, 3, 3, 11, 9 and 7, with
> a mean of 9.1.
> NNNN
> /EX
>