[South Florida DX Association] ARLP025 Propagation de K7RA

[Bill Marx]

ZCZC AP25
> QST de W1AW  
> Propagation Forecast Bulletin 25  ARLP025
> From Tad Cook, K7RA
> Seattle, WA  June 17, 2005
> To all radio amateurs 
> 
> SB PROP ARL ARLP025
> ARLP025 Propagation de K7RA
> 
> If you look at the average of daily sunspot or solar flux numbers
> for the past week, you'll see hardly a change from the previous
> period. This does not mean there was no activity, or even 0
> sunspots, but the average daily solar flux is exactly the same the
> past week as the one previous, and the average daily sunspot number
> was down by less than a point. Sunspot counts rose in the earlier
> period, peaked at the end of that reporting week (which is Thursday
> through Wednesday) and declined over the next seven days. Last
> Friday, June 10, sunspots 775 and 776 were transiting the center of
> the visible solar disk, which meant they were in the best position
> for affecting Earth.
> 
> A Coronal Mass Ejection on June 9 caused a geomagnetic storm on June
> 12, when the arrival of the ejection and solar wind was met with a
> south-pointing interplanetary magnetic field. When the field points
> north, it helps protect the Earth from the effects of solar wind.
> But when it points south, the Earth is vulnerable. On June 13 the
> field again pointed north.
> 
> Currently we are experiencing effects from a coronal mass ejection
> which swept over Earth around 0900z on June 16. This was a weak
> disturbance, but it is followed by a moderate solar wind. The
> expected planetary A index, a measure of geomagnetic stability world
> wide, is expected around 25, 15, 10 and 8 for June 17-20. Solar flux
> is expected to remain below 100 until the end of this month.
> 
> Currently there is a large sunspot detectable on the far side of the
> sun. A large sunspot, number 779, which only emerged this week is
> currently at the center of the visible solar disk, directly facing
> Earth.
> 
> Now let's look at ARRL Field Day, a very popular activity which
> generates a great deal of interest and mail this time of year. The
> dates are June 25-26, and recurring coronal holes and a high speed
> solar wind are expected to result in active to minor storm levels
> around June 24-27. It is difficult to predict with real accuracy
> this far out, but according to the U.S. Air Force the expected
> planetary A index for June 24-27 is 15, 20, 20 and 15. Solar flux
> around that weekend is expected around 85-90. By the way, I found an
> interesting article titled, "Air Force Space Weather Troops," which
> is about a solar observatory the Air Force operates in Puerto Rico.
> The article can be found on the web at,
> http://usmilitary.about.com/library/milinfo/milarticles/blweather.htm.
> 
> Next week we'll revisit Field Day in the hours leading up to next
> weekend. Meanwhile, this weekend in addition to other activities is
> the All Asian DX CW Contest, SMIRK 6-meter Contest, and the Kid's
> Day Operating Event. For Kid's Day info, check
> http://www.arrl.org/FandES/ead/kd-rules.html. Next week is also the
> summer solstice, the longest day of the year in the Northern
> Hemisphere, June 21. This day gets really long the farther north one
> moves in the Northern Hemisphere. For instance, on June 21 in Los
> Angeles the sun will rise at 5:50 AM and set at 8:01 PM, a 14 hour
> and 11 minute period. But in Seattle, the sun rises 29 minutes
> earlier at 5:21 AM and sets a whole hour later than L.A. at 9:01 PM,
> a 15 hour and 41 minute period from sunrise to sunset.
> 
> Another email arrived concerning 6 meter openings. Eric Hall, K9GY
> was operating on Saturday, June 11 from grid square FM08rp at 3,500
> feet elevation west of Shenandoah National Park in northeast
> Virginia. He was mobile with a 6 meter whip on his car top, and
> heard VP5/N4VHF in FL31 (Turks and Caicos Islands). Eric feels he
> nearly worked him when the other station asked for a repeat from the
> Yankee station. He worked stations in FN11, FN20, FN21, FN00, FN01,
> FN30, FN31, FN32 and EM96.
> 
> If you want to locate those grid squares, check the Grid Square
> Conversion site at http://www.amsat.org/cgi-bin/gridconv. It will
> give you latitude/longitude coordinates for any grid square, and
> also works with the more precise 6 character locator. Running it to
> find my grid square from map coordinates, I discovered my 6
> character locator is at CN87uq.
> 
> 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 June 9 through 15 were 99, 103, 85, 85, 73, 44
> and 64 with a mean of 79. 10.7 cm flux was 116.1, 114.3, 108, 103,
> 91.8, 93.8 and 94.5, with a mean of 103.1. Estimated planetary A
> indices were 5, 5, 6, 35, 33, 10 and 21 with a mean of 16.4.
> Estimated mid-latitude A indices were 3, 2, 6, 23, 17, 8 and 14,
> with a mean of 10.4.
> NNNN
> /EX
> 
> 
>