ARRL

ARRL Propagation Bulletin ARLP022 (2000)

SB PROP @ ARL $ARLP022
ARLP022 Propagation de K7VVV

ZCZC AP22
QST de W1AW  
Propagation Forecast Bulletin 22  ARLP022
From Tad Cook, K7VVV
Seattle, WA  June 2, 2000
To all radio amateurs 

SB PROP ARL ARLP022
ARLP022 Propagation de K7VVV

Average solar flux and sunspot numbers for last week were 158.3 and
152.7 respectively, which is down quite a bit from the week before.
Average flux was off nearly 70 points and average sunspot numbers
were down over 80 points when compared to the previous week.
Contesters were lucky last weekend, as the planetary A index was 12
on Saturday and Sunday, but much higher on the days before and after
the weekend.  Polar paths were probably still difficult, as the high
latitude A and K indices were still high on the weekend.  For
instance, while the planetary K index was two and three on Sunday,
the College K index, measured at Fairbanks, Alaska was five and six,
which is at storm levels.

Average solar flux for the month of May was 184.5, about the same as
April, which was 184.2.  Average monthly solar flux numbers from
May, 1999 through May, 2000 were 147.8, 169.8, 165.6, 170.8, 135.7,
164.8, 191.5, 169.8, 159, 174.1, 208.2, 184.2 and 184.5.

For the next few days we should expect a rising solar flux.
Predicted solar flux for Friday through Tuesday is 155, 160, 160,
165 and 165.  Solar flux is expected to peak near 260 around June 12
or 13, based upon the previous solar rotation.  Geomagnetic activity
for the near term looks stable, with planetary A indices for Friday
through Tuesday of 10, 8, 10, 10 and 10.

KV4AC wrote this week asking about the path projections and software
for evaluating propagation.  The one I have used is W6EL's Miniprop.
Unfortunately, this DOS software is no longer published, and the
latest version is no longer available.  But an early 1987 shareware
version is available for FTP, and it works quite well.  It gives
signal level predictions in 2 hour increments and only does five
bands at a time, whereas later versions give levels in half-hour
increments and will display seven frequencies at a time.  One source
for this version is a link on AE0Q's web page at
http://www.qsl.net/ae0q/index.html.

This week, try doing your own path projections.  You can check the
current solar flux over the radio on WWV at 18 minutes after every
hour, or dial 303-497-3235 at any time.  Then after downloading
Miniprop, put in your latitude and longitude for the default values,
select a target, enter the letter F followed by the solar flux, and
the date.  You can find your exact latitude and longitude by
entering your street address at www.mapblast.com.  Select the Create
Map option, and your coordinates will appear at the edge of the map.
Take care when entering the coordinates into Miniprop, because the
conventions between Mapblast and Miniprop are slightly different.
In Miniprop, both coordinates for North American locations will be
positive, whereas in Mapblast one is negative.

Notes to the author are welcome at k7vvv@arrl.net.

Sunspot numbers for May 25 through 31 were 125, 155, 161, 176, 189,
153 and 110 with a mean of 152.7. 10.7 cm flux was 172.8, 167.9,
161.8, 155.9, 149, 146.4 and 154.4, with a mean of 158.3, and
estimated planetary A indices were 31, 23, 12, 12, 24, 21 and 12,
with a mean of 19.3.
NNNN
/EX