[IRCA] Fw: ARLP039 Propagation de K7RA

["Art Blair" <artngwen@xxxxxxxxxx>]

----- Original Message ----- 
From: "W1AW Mailing List" <w1aw-list-request@xxxxxxxxxxxxxxxxx>
To: <artngwen@xxxxxxxxxx>
Cc: <W1AW List:>
Sent: Friday, September 16, 2005 7:37 AM
Subject: ARLP039 Propagation de K7RA


> SB PROP @ ARL $ARLP039
> ARLP039 Propagation de K7RA
> 
> ZCZC AP39
> QST de W1AW  
> Propagation Forecast Bulletin 39  ARLP039
>>From Tad Cook, K7RA
> Seattle, WA  September 16, 2005
> To all radio amateurs 
> 
> SB PROP ARL ARLP039
> ARLP039 Propagation de K7RA
> 
> This week the Sun has given us a tremendous amount of activity in
> the form of large solar flares. A geomagnetic storm is still in
> progress, and the planetary A index from Saturday through Thursday,
> September 10-15, was 30, 105, 66, 51, 25 and 43. These are high
> numbers.
> 
> The average planetary A index for this week more than doubled to
> 43.1. Average daily sunspot numbers more than quadrupled to 71.1.
> These numbers compare the 7 days ending Wednesday, September 14 with
> the previous 7 day period.
> 
> Next week is the Northern Hemisphere's Autumnal Equinox. This period
> could be a good one for HF propagation if solar flares quiet down
> and the sunspot count doesn't sink back toward 0. The sunspot number
> rose above 100 on Sunday, September 11, the first time since August
> 3.
> 
> The source of all this excitement is a single large sunspot group,
> number 798. This spot was just peeking around the edge of the
> visible solar disk on September 9, but by September 14-15 it was
> aimed squarely at our planet. The last time around it was much
> smaller and still emerging, visible until August 24. Although not
> aimed at Earth on September 7, that day it produced an X17 solar
> flare, the fourth largest detected over the past three decades.
> Over the next week it produced 8 more flares, each causing HF radio
> blackouts.
> 
> Of course, VHF operators probably didn't mind all the disruption.
> You can check the 50 MHz Propagation Logger page at,
> http://dxworld.com/50prop.html to see what they've been up to on
> 6-meters, and, http://dxworld.com/files/vhfprop22.htm for a further
> look back.
> 
> Steve Lyon, WB6RIB and several others sent in an article from NASA
> about all this activity in the year before the solar cycle bottom,
> titled "Solar Minimum Explodes." You can read it for yourself on the
> http://science.nasa.gov/headlines/y2005/15sep_solarminexplodes.htm
> web site.
> 
> Over the next few days look for declining geomagnetic numbers, but
> fairly good sunspot and solar flux values. (Remember, HF operators
> generally want the sunspot and the somewhat-related solar flux
> numbers to remain high, with the geomagnetic A index and related K
> index as low as possible). Predicted solar flux for Friday through
> Monday, September 16-19 is 115, 110, 110 and 105. The predicted
> planetary A index for those same days is 25, 15, 10 and 10.
> Geophysical Institute Prague predicts active to minor storm
> conditions for September 16, active conditions on September 17 and
> 20, unsettled to active conditions September 21, unsettled
> conditions for September 18 and 22, and quiet to unsettled
> conditions on September 19.
> 
> Ed Douglass, AA9OZ is trying for his second 5-Band DXCC award. The
> first time around was as 7P8DX in Lesotho from 1986-1992, and this
> time he wants to do it from Sturgeon Bay, Wisconsin, a town just
> below the 45th parallel on a peninsula extending into Lake Michigan.
> He aims to work 100 countries on 75 and 80 meters during the sunspot
> minimum, and asked if the absence of sunspots might improve his
> chances on lower frequencies. Certainly the MUF (Maximum Usable
> Frequency) is lower with fewer sunspots, so openings on 20-15-10
> meters are much less common. But I seemed to recall Carl
> Luetzelschwab, K9LA having something to say about the absence of
> solar activity producing better conditions overall on the low
> frequencies.
> 
> Carl referred me to an interesting article he wrote for the
> September/October 2005 issue of "The DX Magazine" titled "Getting
> Ready for Solar Minimum." Among other issues, the article discusses
> what happens with 160 and 80 meter propagation passing through the
> auroral zone. This includes West Coast North America to Europe,
> Midwest to Europe and Japan, and East Coast to Japan paths. During
> the solar minimum, there is less chance of ionospheric disturbance
> in northern latitudes. Carl writes, "In general, a quiet high
> latitude ionosphere provides the best propagation on the lower bands
> for paths near or going through the auroral zone."
> 
> Although this excellent article is not online, you can find similar
> material by entering a query for +K9LA +"auroral zone" in a search
> engine such as Google. One link returned was for another of our
> bulletins, ARLP008 from 2004, which talked about this same issue,
> and mentions that Carl wrote about this in the March 2004 issue of
> WorldRadio. The bulletin is located at,
> http://www.arrl.org/w1aw/prop/2004-arlp008.html. You can find out
> more about "The DX Magazine" at http://www.dxpub.com/. You can also
> look at current conditions in the auroral zone north of North
> America at,
> http://www.spaceweather.gc.ca/forecastmap_e.shtml.
> 
> Terry Oldham, KH6MT wrote asking about 10 meters, an often difficult
> band at the bottom of the cycle. He lives in North Central Florida,
> between Jacksonville and Tampa, and wants to know when 10 might be
> open to El Paso, Texas next. He mentioned that the window used to
> run from September through April, but last year he saw no window at
> all.
> 
> I told Terry about W6ELprop (the free propagation program for the
> PC, from http://www.qsl.net/w6elprop/) and mentioned he could plug
> in numbers for that path to see what pops up. I tried it, and over
> the approximately 1500 miles at this time of year, a sustained
> sunspot number a little higher than we've seen recently would help.
> Still, if you plug in the average sunspot number for the past week
> (71.1), according to this program propagation is quite possible.
> With about 10 more points, or perhaps going over to the 12 meter
> band, the odds look quite good.
> 
> If you would like to comment or have a tip, email the author at,
> k7ra@xxxxxxxxx
> 
> For more information concerning radio 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. An archive of past
> bulletins is found at, http://www.arrl.org/w1aw/prop/.
> 
> Sunspot numbers for September 8 through 14 were 36, 59, 59, 101, 62,
> 95 and 86 with a mean of 71.1. 10.7 cm flux was 94.1, 99, 116,
> 109.7, 118, 114, and 116.6, with a mean of 109.6. Estimated
> planetary A indices were 8, 17, 30, 105, 66, 51 and 25 with a mean
> of 43.1. Estimated mid-latitude A indices were 5, 12, 15, 53, 32, 26
> and 13, with a mean of 22.3.
> NNNN
> /EX
> 
>

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