[IRCA] Fw: ARLP040 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 29, 2006 6:58 AM
Subject: ARLP040 Propagation de K7RA


> SB PROP @ ARL $ARLP040
> ARLP040 Propagation de K7RA
> 
> ZCZC AP40
> QST de W1AW  
> Propagation Forecast Bulletin 40  ARLP040
>>From Tad Cook, K7RA
> Seattle, WA  September 29, 2006
> To all radio amateurs 
> 
> SB PROP ARL ARLP040
> ARLP040 Propagation de K7RA
> 
> Average daily sunspot numbers were down again this week, but only by
> less than one point, to 12.7. Average daily solar flux was down five
> points from the previous week to 72. Geomagnetic indices were down,
> also by a small amount.
> 
> The Air Force projects that today, September 29, geomagnetic
> conditions will be quiet, with a planetary A index of 8, rising to
> 15, then 20 on Sunday, and dropping back to 8 on Monday, October 2.
> Currently the interplanetary magnetic field is pointed south, which
> signals that Earth is vulnerable to solar flares or solar wind from
> coronal holes. Sunspots 913 and 914 are rotating into view, and
> sunspot number and solar flux should rise slightly by Monday.
> 
> Geophysical Institute Prague projects unsettled conditions for
> September 29, quiet conditions on September 30, unsettled to active
> conditions on October 1, unsettled October 2, quiet to unsettled for
> October 3, then quiet conditions on October 4-5.
> 
> Bill Huntimer, KI0CW in Dell Rapids, South Dakota wrote to ask,
> "Would you explain what sunspots do to radio interference?"
> 
> Sunspots can be great for HF radio propagation. The more sunspots we
> see, the greater the density of charged particles in the ionosphere,
> which reflect or refract radio waves. Higher densities mean higher
> frequencies can propagate worldwide, instead of just passing through
> the ionosphere and off into space. When there are sunspots, there is
> also the possibility of other solar activity, such as solar flares,
> and holes in the Sun's corona, which can spew out a solar wind of
> charged particles. These particles, as well as x-rays from flares,
> may disturb the Earth's magnetic field, and cause charged particles
> in the ionosphere to re-combine, canceling the charge. Lower density
> of charged particles means that the Maximum Usable Frequency is
> lower. In addition, polar cap absorption occurs, so propagation over
> the poles becomes poor.
> 
> Sometimes in the media, we may hear of interference to broadcast TV
> or FM radio signals related to sunspots. The interference can be
> from distant stations, when listeners are accustomed to hearing only
> local stations. The interference is actually due to improved
> propagation.
> 
> 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/ .
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at, k7ra@xxxxxxxxx
> 
> Sunspot numbers for September 21 through 27 were 11, 17, 13, 13, 11,
> 13 and 11 with a mean of 12.7. 10.7 cm flux was 71.4, 72.3, 70.4,
> 69.8, 70.2, 70.7, and 72, with a mean of 71. Estimated planetary A
> indices were 4, 3, 9, 23, 6, 6 and 4 with a mean of 7.9. Estimated
> mid-latitude A indices were 2, 1, 7, 15, 6, 5 and 2, with a mean of
> 5.4.
> NNNN
> /EX
> 
> 
>

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