ARRL

ARRL Propagation Bulletin ARLP020 (2003)

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SB PROP @ ARL $ARLP020
ARLP020 Propagation de K7RA

ZCZC AP20
QST de W1AW =20
Propagation Forecast Bulletin 20  ARLP020
From Tad Cook, K7RA
Seattle, WA  May 16, 2003
To all radio amateurs=20

SB PROP ARL ARLP020
ARLP020 Propagation de K7RA

Disturbed conditions triggered by a continuous solar wind stream
appear to go on and on, week after week, seemingly without end.
Nice quiet conditions would result from a daily A index of 10 or
lower. Average daily conditions near that level haven't been
reported since the week of February 20-26 when the daily average A
index was 11.1, or January 9-15 when it was 9.1.

Conventional wisdom says that disturbed conditions occur more often
when the solar cycle has passed the peak and is headed down, and
recent experience seems to bear this out. Recent forecasts for daily
solar flux and planetary A index don't predict a daily A index below
10 until May 31.

A plot from Jim Secan and Northwest Research Associates shows the
decline of the solar cycle over the past year at
http://www.nwra-az.com/spawx/ssne-year.html. The latest projection
has solar flux rising over the next few days to 110 on Saturday, May
17, 120 on Sunday and 125 on Monday. The daily planetary A index
projection shows an unsettled 15 throughout the weekend, rising to
20 on Monday.

The solar flux and sunspot numbers were lower this week than last,
but the A index was higher. The average daily sunspot number dropped
around 100 points from 146 to 46.4, and daily solar flux was down
over 40 points to 95.5. Average daily A index rose from 20.7 to
29.3.

Last week we mentioned Scott Craig, WA4TTK and his solar plotting
utility freeware available at
http://www.craigcentral.com/mystuff.asp. Scott says he usually gets
100-150 visits per day to his web page, but last Friday when the
bulletin came out he got 270, and Saturday it was 393.

The announcement this week about the new 60-meter band brings
speculation about propagation characteristics. Initially this will
probably be used just for domestic communications, since no other
country has adopted these frequencies for the amateur service. A
quick look with a propagation prediction program shows the band
opening and closing at hours somewhere between the 75 and 40-meter
bands.

With W6ELprop looking from Seattle to Atlanta, assuming that the
band is legal one month from now and the sunspot number is around
100, 60-meters seems to open a half hour earlier than 75- meters and
close a half hour later. Signal strengths during the peak hours,
which for the above parameters are from 0500-1000z, are between the
levels for 40 and 75-meters as well. A similar projection for
mid-September from California to Ohio shows similar characteristics,
although with more hours of darkness the openings are longer.

Mark Roberts, KD5SMF sent an email this week asking for a source for
the numbers used in the W6ELprop software, a free windows-based
program that can be downloaded at http://www.qsl.net/w6elprop/. I
wrote to him and said that it is probably better to take an average
of several days sunspot numbers and use that instead of the latest
daily solar flux. You can get both values at
http://sec.noaa.gov/ftpdir/latest/DSD.txt, and several daily K
indices from http://sec.noaa.gov/ftpdir/latest/DGD.txt.

The latest mid-latitude K index is on WWV at 18 minutes after each
hour, or you can get the WWV message on the telephone at
303-497-3235. The text of that hourly message is available on the
web at http://sec.noaa.gov/ftpdir/latest/wwv.txt.

For more information on propagation and an explanation of the
numbers used in this bulletin see the Propagation page on the ARRL
Web site at http://www.arrl.org/tis/info/propagation.html. You can
write to the author of this bulletin at k7ra@arrl.net.

Sunspot numbers for May 8 through 14 were 33, 23, 22, 47, 66, 59,
and 75, with a mean of 46.4. 10.7 cm flux was 100.9, 97.1, 92.7,
91.5, 93.9, 96.1, and 96.3 with a mean of 95.5. Estimated planetary
A indices were 30, 29, 43, 31, 18, 27, and 27, with a mean of 29.3.
NNNN
/EX

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<P><FONT SIZE=3D2>SB PROP @ ARL $ARLP020</FONT>

<BR><FONT SIZE=3D2>ARLP020 Propagation de K7RA</FONT>
</P>

<P><FONT SIZE=3D2>ZCZC AP20</FONT>

<BR><FONT SIZE=3D2>QST de W1AW&nbsp; </FONT>

<BR><FONT SIZE=3D2>Propagation Forecast Bulletin 20&nbsp; ARLP020</FONT>

<BR><FONT SIZE=3D2>From Tad Cook, K7RA</FONT>

<BR><FONT SIZE=3D2>Seattle, WA&nbsp; May 16, 2003</FONT>

<BR><FONT SIZE=3D2>To all radio amateurs </FONT>
</P>

<P><FONT SIZE=3D2>SB PROP ARL ARLP020</FONT>

<BR><FONT SIZE=3D2>ARLP020 Propagation de K7RA</FONT>
</P>

<P><FONT SIZE=3D2>Disturbed conditions triggered by a continuous solar =
wind stream</FONT>

<BR><FONT SIZE=3D2>appear to go on and on, week after week, seemingly =
without end.</FONT>

<BR><FONT SIZE=3D2>Nice quiet conditions would result from a daily A =
index of 10 or</FONT>

<BR><FONT SIZE=3D2>lower. Average daily conditions near that level =
haven't been</FONT>

<BR><FONT SIZE=3D2>reported since the week of February 20-26 when the =
daily average A</FONT>

<BR><FONT SIZE=3D2>index was 11.1, or January 9-15 when it was =
9.1.</FONT>
</P>

<P><FONT SIZE=3D2>Conventional wisdom says that disturbed conditions =
occur more often</FONT>

<BR><FONT SIZE=3D2>when the solar cycle has passed the peak and is =
headed down, and</FONT>

<BR><FONT SIZE=3D2>recent experience seems to bear this out. Recent =
forecasts for daily</FONT>

<BR><FONT SIZE=3D2>solar flux and planetary A index don't predict a =
daily A index below</FONT>

<BR><FONT SIZE=3D2>10 until May 31.</FONT>
</P>

<P><FONT SIZE=3D2>A plot from Jim Secan and Northwest Research =
Associates shows the</FONT>

<BR><FONT SIZE=3D2>decline of the solar cycle over the past year =
at</FONT>

<BR><FONT SIZE=3D2><A =
HREF=3D"http://www.nwra-az.com/spawx/ssne-year.html">http://www.nwra-az.c=
om/spawx/ssne-year.html</A>. The latest projection</FONT>

<BR><FONT SIZE=3D2>has solar flux rising over the next few days to 110 =
on Saturday, May</FONT>

<BR><FONT SIZE=3D2>17, 120 on Sunday and 125 on Monday. The daily =
planetary A index</FONT>

<BR><FONT SIZE=3D2>projection shows an unsettled 15 throughout the =
weekend, rising to</FONT>

<BR><FONT SIZE=3D2>20 on Monday.</FONT>
</P>

<P><FONT SIZE=3D2>The solar flux and sunspot numbers were lower this =
week than last,</FONT>

<BR><FONT SIZE=3D2>but the A index was higher. The average daily sunspot =
number dropped</FONT>

<BR><FONT SIZE=3D2>around 100 points from 146 to 46.4, and daily solar =
flux was down</FONT>

<BR><FONT SIZE=3D2>over 40 points to 95.5. Average daily A index rose =
from 20.7 to</FONT>

<BR><FONT SIZE=3D2>29.3.</FONT>
</P>

<P><FONT SIZE=3D2>Last week we mentioned Scott Craig, WA4TTK and his =
solar plotting</FONT>

<BR><FONT SIZE=3D2>utility freeware available at</FONT>

<BR><FONT SIZE=3D2><A =
HREF=3D"http://www.craigcentral.com/mystuff.asp">http://www.craigcentral.=
com/mystuff.asp</A>. Scott says he usually gets</FONT>

<BR><FONT SIZE=3D2>100-150 visits per day to his web page, but last =
Friday when the</FONT>

<BR><FONT SIZE=3D2>bulletin came out he got 270, and Saturday it was =
393.</FONT>
</P>

<P><FONT SIZE=3D2>The announcement this week about the new 60-meter band =
brings</FONT>

<BR><FONT SIZE=3D2>speculation about propagation characteristics. =
Initially this will</FONT>

<BR><FONT SIZE=3D2>probably be used just for domestic communications, =
since no other</FONT>

<BR><FONT SIZE=3D2>country has adopted these frequencies for the amateur =
service. A</FONT>

<BR><FONT SIZE=3D2>quick look with a propagation prediction program =
shows the band</FONT>

<BR><FONT SIZE=3D2>opening and closing at hours somewhere between the 75 =
and 40-meter</FONT>

<BR><FONT SIZE=3D2>bands.</FONT>
</P>

<P><FONT SIZE=3D2>With W6ELprop looking from Seattle to Atlanta, =
assuming that the</FONT>

<BR><FONT SIZE=3D2>band is legal one month from now and the sunspot =
number is around</FONT>

<BR><FONT SIZE=3D2>100, 60-meters seems to open a half hour earlier than =
75- meters and</FONT>

<BR><FONT SIZE=3D2>close a half hour later. Signal strengths during the =
peak hours,</FONT>

<BR><FONT SIZE=3D2>which for the above parameters are from 0500-1000z, =
are between the</FONT>

<BR><FONT SIZE=3D2>levels for 40 and 75-meters as well. A similar =
projection for</FONT>

<BR><FONT SIZE=3D2>mid-September from California to Ohio shows similar =
characteristics,</FONT>

<BR><FONT SIZE=3D2>although with more hours of darkness the openings are =
longer.</FONT>
</P>

<P><FONT SIZE=3D2>Mark Roberts, KD5SMF sent an email this week asking =
for a source for</FONT>

<BR><FONT SIZE=3D2>the numbers used in the W6ELprop software, a free =
windows-based</FONT>

<BR><FONT SIZE=3D2>program that can be downloaded at <A =
HREF=3D"http://www.qsl.net/w6elprop/">http://www.qsl.net/w6elprop/</A>. =
I</FONT>

<BR><FONT SIZE=3D2>wrote to him and said that it is probably better to =
take an average</FONT>

<BR><FONT SIZE=3D2>of several days sunspot numbers and use that instead =
of the latest</FONT>

<BR><FONT SIZE=3D2>daily solar flux. You can get both values at</FONT>

<BR><FONT SIZE=3D2><A =
HREF=3D"http://sec.noaa.gov/ftpdir/latest/DSD.txt">http://sec.noaa.gov/ft=
pdir/latest/DSD.txt</A>, and several daily K</FONT>

<BR><FONT SIZE=3D2>indices from <A =
HREF=3D"http://sec.noaa.gov/ftpdir/latest/DGD.txt">http://sec.noaa.gov/ft=
pdir/latest/DGD.txt</A>.</FONT>
</P>

<P><FONT SIZE=3D2>The latest mid-latitude K index is on WWV at 18 =
minutes after each</FONT>

<BR><FONT SIZE=3D2>hour, or you can get the WWV message on the telephone =
at</FONT>

<BR><FONT SIZE=3D2>303-497-3235. The text of that hourly message is =
available on the</FONT>

<BR><FONT SIZE=3D2>web at <A =
HREF=3D"http://sec.noaa.gov/ftpdir/latest/wwv.txt">http://sec.noaa.gov/ft=
pdir/latest/wwv.txt</A>.</FONT>
</P>

<P><FONT SIZE=3D2>For more information on propagation and an explanation =
of the</FONT>

<BR><FONT SIZE=3D2>numbers used in this bulletin see the Propagation =
page on the ARRL</FONT>

<BR><FONT SIZE=3D2>Web site at <A =
HREF=3D"http://www.arrl.org/tis/info/propagation.html">http://www.arrl.or=
g/tis/info/propagation.html</A>. You can</FONT>

<BR><FONT SIZE=3D2>write to the author of this bulletin at =
k7ra@arrl.net.&amp;lt;/FONT>
</P>

<P><FONT SIZE=3D2>Sunspot numbers for May 8 through 14 were 33, 23, 22, =
47, 66, 59,</FONT>

<BR><FONT SIZE=3D2>and 75, with a mean of 46.4. 10.7 cm flux was 100.9, =
97.1, 92.7,</FONT>

<BR><FONT SIZE=3D2>91.5, 93.9, 96.1, and 96.3 with a mean of 95.5. =
Estimated planetary</FONT>

<BR><FONT SIZE=3D2>A indices were 30, 29, 43, 31, 18, 27, and 27, with a =
mean of 29.3.</FONT>

<BR><FONT SIZE=3D2>NNNN</FONT>

<BR><FONT SIZE=3D2>/EX</FONT>
</P>

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