[South Florida DX Association] ARLP033 Propagation de K7RA

[Bill Marx]

> QST de W1AW  
> Propagation Forecast Bulletin 33  ARLP033
> From Tad Cook, K7RA
> Seattle, WA  August 5, 2005
> To all radio amateurs 
> 
> SB PROP ARL ARLP033
> ARLP033 Propagation de K7RA
> 
> Average daily sunspot numbers rose over 68 points this week to 83.7,
> when compared to last week's numbers.  Note this is four weeks after
> the recent large number of sunspots around the beginning of July,
> which corresponds to the rotation of the sun relative to Earth.
> That area of the sun is now back in view, but with sunspots
> diminished.
> 
> The reporting week began with heightened geomagnetic activity on
> July 28, but it quieted down.  Prediction for the next few days is
> for solar flux to remain above 100, which is expected until August
> 10.  Current geomagnetic conditions are slightly unsettled, but
> after August 10 are predicted to be quiet.  Barring any unexpected
> solar flare, expect good conditions, at least relative to recent HF
> propagation at this lower spot on the solar cycle.  Also note that
> the Northern Hemisphere is about half way between the longest day of
> the year and the fall equinox, and fall is good for HF propagation.
> 
> July ended this week, so now is a good time to look at monthly
> averages to see if we can spot trends.  What we see is a tremendous
> variation from month-to-month, with a rise in average sunspot and
> solar flux numbers for July, due to the unusually large number of
> sunspots early in the month.
> 
> The average daily sunspot numbers for the months October 2004
> through July 2005 were 77.9, 70.5, 34.7, 52, 45.4, 41, 41.5, 65.4,
> 59.8 and 68.7.  Average daily solar flux for the same months was
> 106, 113.7, 95, 102.3, 97.2, 89.9, 85.9, 99.5, 93.7 and 96.5.  
> Looked at in isolation, the numbers since early 2005 almost suggest
> a rising solar cycle.
> 
> The overall trend for the remainder of this sunspot cycle will be
> down, and it becomes more obvious when we average the numbers over a
> long period.  Currently we are looking to reach solar minimum around
> the end of 2006.  Our bulletin has reported this for some time now,
> and this is based on the table of predicted smoothed sunspot numbers
> that appears occasionally in the back of the weekly Preliminary
> Report and Forecast from NOAA Space Environment Center, found at
> http://www.sec.noaa.gov/weekly/index.html.  This week's copy number
> 1561 at http://www.sec.noaa.gov/weekly/pdf/prf1561.pdf contains that
> table, but I noticed that looking back over the past few years shows
> the predicted values out to the end of 2007, just as it does today.
> 
> Look at this table for predicted smoothed sunspot numbers from four
> years ago, in August 2001, and compare it to the table in the latest
> issue noted above:
> 
> http://www.sec.noaa.gov/weekly/pdf2001/prf1354.pdf
> 
> Even back in 2001 the predicted low numbers for the end of next year
> were the same as today's prediction.  What changed are the predicted
> numbers for a few months from now, which are higher than predicted
> four years ago, and of course the actual smoothed numbers for all
> that time in between differ also.
> 
> We must go back to 2000 to find tables that end earlier than 2007.
> Here is one from August 2000 which ends in 2005:
> 
> http://www.sec.noaa.gov/weekly/pdf2000/prf1301.pdf
> 
> Until I rechecked this, I thought the table was perhaps updated
> yearly, with another year in the future added on.  I have a question
> in to the NOAA Space Environment Center about this, plus another
> question about the July 18 report of a sunspot number of -1 that we
> covered recently.  Perhaps next week's bulletin will have more on
> this.
> 
> Vic Woodling, WB4SLM wrote about recent VHF DX, but on the FM
> broadcast band, about half way between our own six and two meter
> bands.  Vic's girlfriend lives near Haysville, North Carolina, in
> grid square EM85, and around noon local time on Tuesday, August 2
> she heard KRKX in Billings, Montana on 94.1 MHz on her car radio.
> The strong signal was full-quieting, and the KRXK transmitter site
> is in grid square DN55, a little less than 1500 miles away.
> 
> If you would like to comment or have a tip, email the author at,
> k7ra at arrl.net.
> 
> 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 July 28 through August 3 were 29, 69, 62, 110,
> 102, 112 and 102 with a mean of 83.7. 10.7 cm flux was 95.8, 103.7,
> 105, 109.7, 111.2, 110.2 and 108.9, with a mean of 106.4. Estimated
> planetary A indices were 28, 19, 16, 9, 16, 12 and 11 with a mean of
> 15.9.  Estimated mid-latitude A indices were 18, 14, 11, 10, 18, 9
> and 6, with a mean of 12.3.
> NNNN
> /EX
>