[SFDXA] ARLP052 Propagation de K7RA

[Bmarx@bellsouth.net]

> 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, 2018
> To all radio amateurs 
> 
> SB PROP ARL ARLP052
> ARLP052 Propagation de K7RA
> 
> No sunspots over our reporting week, December 20-26, so compared to
> the previous seven days average daily sunspot number declined from
> 3.4 to 0.
> 
> Average daily solar flux was 70, down slightly from 70.4.
> 
> Average planetary A index increased from 4.1 to 4.3, while average
> mid-latitude values went from 3 to 4.
> 
> Predicted solar flux is 69 on December 28 through January 4, 72 on
> January 5, 70 on January 6-13, 69 on January 14 through 18, 71 on
> January 19-26, 72 on January 27 through February 1, 70 on February
> 2-9, and 69 on February 10.
> 
> Predicted planetary A index is 8, 12, 8, 12 and 10 on December 28
> through January 1, 5 on January 2-4, then 10, 10 and 8 on January
> 5-7, 5 on January 8-12, 8 on January 13, then 5, 5 and 12 on January
> 14-16, 5 on January 17-19, 8 on January 20, 5 on January 21-23, then
> 8, 12, 10 and 8 on January 24-27, 5 on January 28-29, 10 and 12 on
> January 30-31, 10 on February 1-2, 8 on February 3, and 5 on
> February 4-10.
> 
> Geomagnetic activity forecast for the period December 28, 2018 to
> January 23, 2019 from F.K. Janda, OK1HH.
> 
> "Geomagnetic field will be:
> Quiet on January 10-12, 22-23
> Quiet to unsettled on January 13, 19
> Quiet to active on December 28, 31, January 1-2, 9, 20
> Unsettled to active on December 29, (30,) January (3-5,) 6-8, 14, 17-18, 21
> Active to disturbed on January (15-16)
> 
> "Solar wind will intensify on December 28-31, January 1, (3-4,) 5-7,
> (8, 13-14,) 15-16, (17-19)
> 
> "Parenthesis means lower probability of activity enhancement."
> 
> Al Brown, W1VTP of Manchester, New Hampshire sent this email:
> 
> "I manage The Vermont Net on 3975 kHz at 2330 UTC. We have been
> having propagation issues since November. I recall similar
> difficulties back in 2009 and it straightened out somewhere around
> mid Feb 2010. I have used the foF2 map (see
> https://www.sws.bom.gov.au/HF_Systems/6/5) put out by the Australian
> government for some time but it doesn't always make sense. I
> understand that amateur radio operators are mostly interested in DX
> (make that 'long haul') propagation. But some of us have regional
> nets with average distance of 100 miles.
> 
> "Do you have any other explanation where I could predict propagation
> for a given night? I'm thinking it may have something to do with a
> disturbance in the magnetosphere and the effect of coronal dark
> holes when pointed at earth but do not have any reference material
> to back that up.
> 
> "The closest thing I have is that foF2 map but it doesn't always
> work out that way."
> 
> We covered the same issue in this bulletin in the past, but I can't
> locate the bulletin. This happens when sunspot numbers are too low
> to support local propagation on 75-80 meters. We might think of
> local nets in that part of the spectrum using groundwave
> propagation, but for wider coverage beyond line-of-sight it depends
> on high angle signals reflecting back from the ionosphere.
> 
> This is why NVIS antennas are useful (see
> https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave ).
> 
> When I asked K9LA about this, Carl responded, "The MUF can be low
> enough that high angle 75m/80m signals go thru the ionosphere at
> night during the winter (especially at solar minimum). As you know,
> with high angle signals, the MUF is pretty close to foF2 - so foF2
> could be a good indicator. You may have to modify foF2 a bit based
> on distance. And having an ionosonde near you would be best."
> 
> Here is a site with a number of links to ionosondes:
> 
> http://giro.uml.edu/IonogramMovies/
> 
> Note the link to Millstone Hill, which may be the closest ionosonde
> to W1VTP.
> 
> Click on the MHJ45 link.
> 
> Clicking on that link goes to a page with ionosonde data from 1992
> to 2018.
> 
> If you click on 2018, it will take you to links for all 12 months of
> the year. Click on December, and click on the latest date, and you
> will see links for every 15 minutes of the day. I clicked on the
> latest one, which was for 0930 UTC at the time. It showed the foF2
> value at 2.45 MHz, which is too low to support local high angle
> coverage for 75 meters, but 160 meters should work.
> 
> I see there are links to ionosondes at Wallops Island (Virginia),
> Boulder (Colorado), Eglin AFB (Florida), Idaho National Labs and
> many other locations around the globe.
> 
> K9LA suggested that the net could QSY to 160 meters when this
> happens.
> 
> The ionogram I am looking at currently can be seen here:
> 
> https://bit.ly/2CBuC5A
> 
> You see MHz on the X-axis and timing on the Y-axis. A chirp signal
> is swept across the HF spectrum, and the wispy looking echoes are
> what comes back. The various timings reveal the elevation of ionized
> layers.
> 
> This tool should help to get a handle on this propagation problem.
> 
> From 0000-2359 UTC on January 1, is the annual ARRL Straight Key
> Night operating event:  http://www.arrl.org/straight-key-night
> 
> Dr. Tamitha Skov put out this video shortly after Propagation
> Forecast Bulletin ARLP051 was released last week, so this is a
> little out of date:
> 
> https://www.youtube.com/watch?v=wt-T-mbt5Ag
> 
> You can check here for her more recent dispatches:
> 
> http://www.spaceweatherwoman.com/
> 
> 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
> 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/.
> 
> 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 20 through 26, 2018 were 0, 0, 0, 0, 0,
> 0, and 0, with a mean of 0. 10.7 cm flux was 69.8, 71.1, 71, 70.2,
> 69.5, 69.6, and 68.7, with a mean of 70. Estimated planetary A
> indices were 12, 5, 3, 3, 4, 4, and 3, with a mean of 4.9. Estimated
> mid-latitude A indices were 9, 4, 3, 3, 3, 4, and 2, with a mean of
> 4.
> NNNN
> /EX