[SFDXA] ARLP052 Propagation de K7RA

Mon Dec 28 17:39:24 EST 2015

> SB PROP @ ARL $ARLP052
> ARLP052 Propagation de K7RA
> 
> ZCZC AP52
> QST de W1AW  
> Propagation Forecast Bulletin 52  ARLP052
> From Tad Cook, K7RA
> Seattle, WA  December 28, 2015
> To all radio amateurs 
> 
> SB PROP ARL ARLP052
> ARLP052 Propagation de K7RA
> 
> This bulletin was released on Christmas Day. The last time Christmas
> fell on a Friday (our normal day for publishing this bulletin) was
> back in 2009, and we released it the day before:
> 
> http://www.arrl.org/w1aw-bulletins-archive/ARLP053/2009
> 
> Note that the solar indices for that week were no better than for
> this past week, six years later.
> 
> This is the last propagation bulletin for 2015, and the next
> bulletin will be released next Friday on January 1, 2016.
> 
> Over the past week, average daily sunspot numbers rose just 1.6
> points to 49.6 compared to the previous seven days, December 10-16.
> Average daily solar flux rose from 102.2 to 122.3 for the December
> 17-23 reporting period.
> 
> A big geomagnetic storm on Sunday, December 20 drove our geomagnetic
> averages way up this week. On that day the mid-latitude A index
> (recorded in Virginia) reached 33, the planetary A index (recorded
> at a number of northern hemisphere sites) was 66, and the college A
> index (recorded near Fairbanks, Alaska) was 89.
> 
> The day before, at 2323 UTC on December 19, the Australian Space
> Forecast Centre issued a geomagnetic warning:
> 
> "Geomagnetic disturbance in progress following a CME impact after
> 1500 UTC December 19. Expect Active geomagnetic conditions December
> 20.
> 
> Increased geomagnetic activity expected due to coronal mass ejection
> from 20-21 December 2015."
> 
> Then on December 23, Spaceweather.com sent out this bulletin:
> 
> "A new sunspot (AR2473) is growing rapidly in the Sun's southern
> hemisphere, more than quadrupling in size in the past 24 hours.
> Crackling with M-class solar flares, the sunspot has already caused
> several minor shortwave radio blackouts, mainly south of our
> planet's equator. More flares and radio blackouts are in the offing
> as the growing sunspot turns toward Earth. Visit
> http://spaceweather.com for more information."
> 
> Over this reporting week (December 17-23) average planetary A index
> rose from 9.9 to 21.7 and average mid-latitude A index rose from 6.6
> to 12.6.
> 
> Predicted solar flux for the near term is 130 on December 25, 125 on
> December 26-31, then 115, 110 and 105 on January 1-3, 110 on January
> 4-6, 115 on January 7-9, 120 on January 10-13, 118 on January 14-15,
> 115 on January 16, 120 on January 17-18, then 115, 105 and 100 on
> January 19-21, 98 on January 22-23, 95 on January 24-25, 98 on
> January 26-27, and 100 on January 28-29.
> 
> Predicted planetary A index is 12, 10, 8 and 6 on December 25-28, 5
> on December 29-31, then 15, 20, 18 and 10 on January 1-4, then 8,
> 20, 18 and 12 on January 5-8, then 10, 20, 18, 10 and 8 on January
> 9-13, and 5 on January 14-16.
> 
> OK1MGW from the Czech Propagation Interest Group sends us his
> geomagnetic prediction this week, and it says to expect the
> geomagnetic field to be quiet to active December 25-28, quiet to
> unsettled December 29, mostly quiet December 30-31, active to
> disturbed January 1-2, quiet to active January 3, quiet to unsettled
> January 4, quiet to active January 5, active to disturbed January 6,
> quiet to active January 7, quiet to unsettled January 8-9, active to
> disturbed January 10, quiet to active January 11, quiet to unsettled
> January 12-14, mostly quiet January 15-17, quiet on January 18-19,
> and quiet to unsettled January 20.
> 
> OK1MGW expects increased solar wind on December 25-28, January 1-3,
> 5-6, and 10-11.
> 
> The Winter Solstice was three days ago, on Tuesday, December 22,
> 2015.  Now the days will get longer for the next six months, until
> the Summer Solstice in the Northern Hemisphere, June 20, 2016.
> Spring begins at the Vernal Equinox, March 19-20, 2015.
> 
> As the days get longer, HF conditions will generally improve in the
> Northern Hemisphere. We can test some paths with a simple free
> program, W6ELprop.
> 
> Testing from Dallas, Texas to Germany, a path of 8,222 km (5,109
> miles) on the shortest day of 2015 we can see that 15 meters has the
> best possibility of propagation from 1500-1630 UTC with an A rating
> (75-100% chance of communication) at 23 dB above .5 microvolt at the
> receiving end) and a B rating (50-74% probability) 1430-1700 UTC.
> 
> At the end of January 2016, the opening runs from 1430-1730 UTC for
> the B rating, (A rating 1500-1700 UTC), with signals about 2 dB
> lower.
> 
> At the Vernal Equinox, on March 20, 2016 the 15 meter opening
> stretches from 1400-2100 UTC. All of these tests were done with a
> solar flux of 127, to look at seasonal variation only.
> 
> Over the same path on 17 meters on December 22, 2015 it is open from
> 1400-1730 UTC, on January 31 1400-1830 UTC and on March 20, 2016,
> 1300-2200 UTC.
> 
> But for lower frequencies, such as 75 meters, conditions are better
> during long periods of darkness, such as late December. On December
> 22, over the same path 75 meters looks best 2330-0830 UTC, but on
> January 31 the best conditions are from 0030-0730 UTC and on March
> 20 conditions look best at 0200-0530 UTC.
> 
> 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 web page at,
> http://arrl.org/propagation-of-rf-signals. For an explanation of the
> numbers used in this bulletin, see
> http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
> propagation bulletins is at
> http://arrl.org/w1aw-bulletins-archive-propagation. More good
> information and tutorials on propagation are at http://k9la.us/.
> 
> My own archives of the NOAA/USAF daily 45 day forecast for solar
> flux and planetary A index are in downloadable spreadsheet format at
> http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .
> 
> Click on "Download this file" to download the archive, and ignore
> the security warning about file format. Pop-up blockers may suppress
> the download.
> 
> Monthly propagation charts between four USA regions and twelve
> overseas locations are at http://arrl.org/propagation.
> 
> Instructions for starting or ending email distribution of ARRL
> bulletins are at http://arrl.org/bulletins.
> 
> Sunspot numbers for December 17 through 23 were 52, 49, 44, 33, 38,
> 68, and 63, with a mean of 49.6. 10.7 cm flux was 117.8, 117.1, 119,
> 116.6, 121.7, 130.1, and 133.9, with a mean of 122.3. Estimated
> planetary A indices were 7, 5, 12, 66, 38, 13, and 11, with a mean
> of 21.7. Estimated mid-latitude A indices were 6, 4, 8, 33, 22, 8,
> and 7, with a mean of 12.6.
> NNNN
> /EX