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ARRL Propagation Bulletin ARLP022 (2010)

ARLP022 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 22  ARLP022
From Tad Cook, K7RA
Seattle, WA  June 4, 2010
To all radio amateurs 

ARLP022 Propagation de K7RA

Average daily sunspot numbers were up nine points to 25.3 for this
week, compared to the May 20-26 period.  Average daily planetary A
index rose nearly ten points to 14.3, and this rise in geomagnetic
instability came with the increase in solar activity.

Sunspot group 1072, reported in last week's bulletin, was visible
for nine days, until May 28.  When it was gone on May 29, three new
groups appeared, 1073, 1074 and 1075.  On May 29-31 the daily
sunspot numbers were 43, 40 and 39, but geomagnetic indices were
high as well, with the planetary A index at 33 on May 29, and
planetary K index up to five.  On the same day the college A index
(Alaska) was 53, with college K index as high as seven.

On May 31 group 1074 was gone, and it was the last day groups 1073
and 1075 were still visible.  On that day new group 1076 appeared,
and through June 3 the total area (in millionths of a solar
hemisphere) was 20, 20, 40 and 190.  The increase from June 2 to
June 3 was big (up 375%), but curiously the sunspot number for those
dates declined slightly, from 18 to 17.  Solar flux rose from 74 to

The prediction from USAF and NOAA has solar flux slowly declining in
the short term, from 75 for June 4 to 74 on June 5-6, 73 June 7-9,
72 on June 10, and 70 on June 11-17, then rising to a peak of 82 on
June 28.  Predicted planetary A index for the next seven days, June
4-10, is 10, 8, 5, 8, 8, 5 and 5.

Geophysical Institute Prague predicts quiet conditions June 4, quiet
to active June 5-6, quiet to unsettled June 7-8, and quiet again on
June 9-10.

Some may have noticed at that NOAA showed a
solar flux value of zero for June 2, which is impossible.  Don't
know how that was left out, but you can always get the data from the
source at which shows a solar flux value
of 74.6 for that day.

ARRL Field Day is June 26-27, and this coincides with what may be
the next short term peak in solar activity, according to the NOAA
and USAF prediction, which calls for solar flux values for June
25-28 at 80, 80, 80 and 82.

Field Day 2009 was spotless, in fact there were no sunspots at all
between June 25 and July 2, 2009.  Suppose that there are sustained
daily sunspot numbers around 25 for the days leading up to Field Day
2010?  What differences could we expect?

Checking W6ELprop from Southern California to Ohio, for example,
shows very little difference, except on 15 meters there is a much
greater chance for an opening.  Both show 40 meters opening up after
0000z, reaching optimum signal strength 0330-1030z.  Both show 20
meters open through the day, but weakest periods around 1330-1430z
and 2300-0000z, and strongest signals through the night, 0100-1200z.

We see similar results from Atlanta to the center of the continental
United States, somewhere in Kansas.  The path is quite a bit
shorter, and we see 20 meters opening a half hour earlier than last
year, at 1500z and lasting until 2130z, a half hour later than last

A similar test from Hawaii to the mainland shows a big improvement
over last year, especially on higher frequencies, such as 15 meters.
In Field Day there is no bonus for DX, and it isn't like ARRL
Sweepstakes in which multipliers are earned for each new section
worked, so the only incentive is to work as many stations as
possible.  But for a Field Day station in Hawaii, the increased
solar activity will make a big difference in the number of stations
they can work.

Now at the beginning of a new month, we can look at our quarterly
moving averages for sunspot numbers.  We use a sliding three month
window for averaging the data, so the latest number is for March 1
through May 31, and centers on April.  For May 2009 through April
2010 the 3-month averages are 4.2, 5.2, 4, 4, 4.6, 7.1, 10.2, 15.2,
22.4, 25.7, 22.3 and 18.5.  You can see that the numbers have
declined a bit.

The monthly averages of daily sunspot numbers for 2010 are 21.3, 31,
25.2, 11.2 and 20.

Floyd Chowning, K5LA and K5PHF, both in DM61 in El Paso, Texas and
K7ICW in Las Cruces, New Mexico (DM62) all worked K7MAC in Nampa,
Idaho (DN13) on June 2 at 1758z on 2 meter SSB.  This rare
sporadic-e opening lasted 30 minutes.  The distance from K5LA to
K7MAC is 973 miles, according to my calculations.

If you check the K5LA entry at you will
see some detail on his propagation beacons on 30, 17, 10 and 6
meters, and his participation in

David Greer, N4KZ of Frankfort, Kentucky wrote a detailed
description of his 2 meter sporadic-E adventure.

"It's June so it must be time for the VHF bands to start rockin'.
They did not disappoint on June 3 with 6 meters providing
three-dozen SSB and CW QSOs from central Kentucky (EM78) to the West
Coast. Of course, the day before wasn't shabby either with a dozen
contacts into W1 and the Caribbean.

"But it was June 3 that provided some memorable QSOs. In the midst
of handling a pile-up of West Coast callers, I got a call from
KD5CCG in Arkansas. That got my attention because it showed the
E-skip distance was shortening up -- often a tip-off that E-skip
will show up on 2 meters.

"So I set my TS-2000 and amp on 144.200 MHz and called several CQs
while beaming west. Nothing, zilch. So I turned on the squelch and
went back to my Icom Pro 3 on 6 meters.

"At 0047 UTC, N0YK came on the 2-meter frequency with an S9 plus SSB
signal calling CQ. I answered him and we both logged 59 reports.
He's in Kansas, DM98. That's western Kansas, almost to the Colorado
line. Exactly 10 minutes later, WB2FKO, DM65, in New Mexico came
roaring in with a strong "CQ 2-meter E-skip. Beaming east.

"Bingo, he was in my log too but not before I nervously asked him to
repeat his call twice. Even after 41 years of ham radio, such a
contact gives me chills. My logging program shows 1,173 miles
between our QTHs. I've been on and off 2-meter SSB since 1975 and it
was only the second time I had worked New Mexico from Kentucky. Wow,
nearly 1,200 miles on 2 meters!

"At 0106 UTC, I worked N0QKY, also in Kansas and then made a quick
QSO a minute later with KA0RID, another Kansas station. It's about
600 miles from my location to central Kansas and those are great
2-meter contacts but the nearly 1,200 mile QSO with New Mexico was
really special. During the opening, I copied but did not work K7ICW,
New Mexico, and N0POH, Colorado. At that point, things were quite
busy on 144.200 MHz with QSOs, CQs and QRZs galore. I do wish guys
would spread out a bit more during these openings!

"More than 30 minutes after I first heard and worked N0YK, I was
still copying him but the signals were in the noise as the 2-meter
E-skip opening was fading.

"I have modest stations on both bands. I run 200 watts out and a
9-element M2 Yagi at 60 feet on 2 meters and 100 watts out to a
4-element Yagi at 55 feet on 6. Antennas are important but time and
time again it's proven that much of the battle at VHF is about being
in the right place at the right time."

Thanks, Dave!

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at, For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for May 27 through June 2 were 11, 12, 43, 40, 39,
14, and 18 with a mean of 25.3. 10.7 cm flux was 72.7, 73.2, 73.7,
73, 72, 72.7 and 74 with a mean of 73. Estimated planetary A indices
were 4, 10, 33, 19, 16, 12 and 6 with a mean of 14.3. Estimated
mid-latitude A indices were 1, 7, 15, 14, 14, 9 and 4 with a mean of


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