[South Florida DX Association] ARLP037 Propagation de K7RA

[Bill Marx]

 SB PROP ARL ARLP037
> ARLP037 Propagation de K7RA
> 
> Average daily sunspot numbers were down only slightly this week,
> from 27 to 25.3. There were two days this week when the sunspot
> number was 0, and we should see more zero sunspot days than we're
> currently experiencing as we move closer to the bottom of the
> sunspot cycle.
> 
> The last solar minimum was centered near October 1996, according to
> the NOAA SEC graphs on page 11 of their weekly report at,
> http://www.sec.noaa.gov/weekly/pdf/prf1618.pdf.
> 
> If you look at the average sunspot numbers reported in our
> propagation forecast bulletins from September 13, 1996 to October
> 25, 1996 (located on the web at,
> http://www.arrl.org/w1aw/prop/1996-index.html) you'll see week after
> week of no sunspots.
> 
> Currently we're observing average daily sunspot numbers near 25 for
> this week, 27 for last, 22 the previous week, and 34 prior to that.
> According to weekly NOAA SEC sunspot predictions, on the web at,
> http://sec.noaa.gov/ftpdir/weekly/Predict.txt, these averages are
> above the high end for this month and last, and the minimum is about
> six months away. But look back on that 1996 index mentioned above,
> at the numbers reported in this bulletin six months prior to the
> last minimum. Weekly averages reported here during April 1996 were
> near 12, 2, 7, and 20. Does this suggest the sunspot minimum is
> further away, rather than next spring?
> 
> Also note on page 11 in that first reference in the second
> paragraph, the spacing of the sunspot cycle minimums. From the end
> of cycles 17 to 19 they are a little over ten years apart, from 1944
> to 1954 and 1964. Then it jumps less than 12 years (from October
> 1964 to June 1976), and it goes back to a little over ten years from
> 1976 to 1986, and then 1996. Next spring will be a bit less than 11
> years since the last minimum.
> 
> Right now is a fairly good time for long-distance HF communications,
> because the geomagnetic field is mostly stable, sunspots haven't
> disappeared, and we are close to the Autumnal Equinox. Running
> intercontinental paths with ACE-HF propagation software shows very
> little in the way of openings on the upper bands above 20 meters,
> with the best bets on 40, 30 and 20 meters.
> 
> 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 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 August 31 through September 6 were 39, 32, 27,
> 0, 0, 26 and 53 with a mean of 25.3. 10.7 cm flux was 83.2, 76.9,
> 75.6, 76.5, 79, 80.4, and 84, with a mean of 79.4. Estimated
> planetary A indices were 8, 13, 7, 6, 23, 8 and 7 with a mean of
> 10.3. Estimated mid-latitude A indices were 6, 8, 6, 6, 15, 7 and 6,
> with a mean of 7.7.
> NNNN
> /EX
> 
> 
>