[South Florida DX Association] ARLP052 Propagation de K7RA

[Bill Marx]

> SB PROP ARL ARLP052
> ARLP052 Propagation de K7RA
> 
> The 7-day averages for solar flux and sunspot numbers declined this
> week, and the averages for geomagnetic A index rose. The average
> daily sunspot number declined over 19 points to 26.9, and average
> solar flux was down over 8 points to 88.7. Sunspot counts have been
> quite low, and will continue their retreat for about 2 more years.
> 
> If you look on page 12 of the latest edition of NOAA SEC's weekly
> Preliminary Report and Forecast of Solar Geophysical Data (for this
> week see, http://www.sec.noaa.gov/weekly/pdf/prf1528.pdf , and the
> index at, http://www.sec.noaa.gov/weekly/index.html) you'll observe
> the predicted smoothed sunspot number for this month is 30, December
> 2005 is 10, and the lowest value is 5, projected for December 2006
> and January 2007.
> 
> Following the December three years from now, in 2008, the monthly
> sunspot count for cycle 24 should increase rapidly. But in between
> will be some long spells with no sunspots at all. It is interesting
> to note that the longest period of 0 sunspots in recent memory was a
> little over 7 weeks during September and October of 1996, and the
> next low period we are talking about predicted for the end of 2006
> is about 10 years after that.
> 
> Average sunspot cycles are about 11.1 years long, but have been as
> short as 7 and as long as 17 years. The average rise from minimum to
> maximum takes 4.8 years, and the average decline is around 6.2
> years, so cycles rise faster than they decline.
> 
> The most active day in terms of geomagnetic indices over the past
> week was Monday, December 12, when a robust solar wind stream drove
> the mid-latitude A index to 24, the planetary A index to 36, and
> Alaska's college A index to 48. The quiet period this week was 2-3
> days later on December 14-15 when the mid-latitude A index was 4 and
> 3.
> 
> Over last weekend during the ARRL 10-Meter Contest, Sunday had worse
> conditions than Saturday. There were periods when I couldn't hear
> anything from Seattle on 10-meters except stations in South America.
> This was the north-south trans-equatorial propagation commonly
> observed during periods of high geomagnetic activity. It isn't a
> case of propagation being enhanced over the north-south path, but
> this might be the only propagation mode available.
> 
> Our earth is now passing through a solar wind stream from a coronal
> hole. For Friday, December 17 the predicted planetary A index is 20,
> followed by 15, 8 and 5 for Saturday through Monday. We may expect
> slightly higher solar flux (which is somewhat related to sunspot
> counts) with this weekend's flux value around 90. This is expected
> to rise to around 105 by December 23.
> 
> A note from the Geomagnetic Dept of the Geophysical Institute of
> Prague says December 19 and 20 should be quiet, December 21 quiet to
> unsettled, and December 18 and 23 unsettled.
> 
> If you would like to comment or have a tip, email the author at,
> k7ra at arrl.net.
> 
> For more information concerning 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.
> 
> Sunspot numbers for December 9 through 15 were 39, 39, 16, 26, 22,
> 18 and 28 with a mean of 26.9. 10.7 cm flux was 87.4, 84.8, 89.8,
> 90.5, 89.7, 89.3 and 89.3, with a mean of 88.7. Estimated planetary
> A indices were 8, 10, 15, 36, 11, 7 and 6 with a mean of 13.3.
> Estimated mid-latitude A indices were 7, 8, 11, 24, 8, 4 and 3, with
> a mean of 9.3.
> NNNN
> /EX
>