ARRL

ARRL Propagation Bulletin ARLP043 (1999)

SB PROP @ ARL $ARLP043
ARLP043 Propagation de K7VVV

ZCZC AP43
QST de W1AW  
Propagation Forecast Bulletin 43  ARLP043
From Tad Cook, K7VVV
Seattle, WA  October 22, 1999
To all radio amateurs 

SB PROP ARL ARLP043
ARLP043 Propagation de K7VVV

Solar flux had a spectacular increase over the past week, with
values around 200.  The official solar flux number is taken from the
Penticton, British Columbia observatory at 2000z, but there are
actually three measurements daily.  The highest value for the week
was at 2300z on Thursday, October 14, when the flux reached 200.6.
Flux values stayed above 190 for the thrice-daily readings until
2000z on Saturday, when the flux was 189.0.

Geomagnetic conditions were quite stormy from October 10-17, when
the planetary A index ranged from 21 to 34.  This was caused by a
series of coronal holes and flares, streaming charged particles in a
high speed solar wind.  From October 18-20 the planetary A index was
in the single digits, with many periods having a K index of 1.  On
October 21, the effects of a coronal mass ejection a couple of days
earlier could be seen, with K indices back up above 4.  You can see
geomagnetic indices in three hour intervals for planetary, mid and
high latitudes at gopher://sec.noaa.gov/00/indices/DGD.

Earlier in the week the forecast for planetary A index for this
coming weekend showed a value of 20.  The latest forecast for the A
index for Friday is 25 to 30, 10 for Saturday, and 15 to 20 on
Sunday, due to a coronal hole.  The predicted solar flux is 150, 145
and 140 for the same period.  After the weekend the solar flux is
expected to bottom out around 125 from October 26-29, then rise back
to 200 around November 10 or 11.  Geomagnetic indices are expected
to be mostly low until November 6, when recurring coronal holes are
expected to keep conditions unsettled or stormy through November 13.

On October 12 and 13, the Solar and Heliospheric Observatory (SOHO)
detected two large coronal mass ejections from the sun over an eight
hour period.  You can see photos, an article and even an animation
of this event if you look on the NASA web site at
http://science.msfc.nasa.gov/newhome/headlines/ast15oct99_1.htm.

Last week NASA released an article about solar cycle progress at
http://science.msfc.nasa.gov/newhome/headlines/ast14oct99_1.htm.  It
quotes work by David Hathaway, a solar physicist at the Marshall
Space Flight Center indicating that the peak of the current solar
cycle should be around the middle of next year.

''Our predictions have consistently targeted 2000 as the beginning
of solar maximum,'' said Hathaway, ''but the latest numbers suggest
that the peak sunspot count in 2000 will be a bit lower than
expected.  The projected peak is comparable to, but lower than the
peaks of the last two maxima (in 1989 and 1978). That would put all
three of the recent sunspot maxima in the same class -- above
average compared to all the sunspot cycles since the mid 1700's.''
He went on to state that the peak of the solar cycle is actually a
broad peak, not an event centered around a certain date.  He
predicts that solar activity should be highest in 2000 and 2001, and
then perhaps in 2002 it will decline to where it is now in October
1999.

Sunspot numbers for October 14 through 20 were 206, 130, 189, 169,
135, 169 and 193 with a mean of 170.1. 10.7 cm flux was 199.8,
198.2, 189, 178, 172.7, 169.6 and 158.8, with a mean of 180.9, and
estimated planetary A indices were 24, 24, 21, 26, 6, 7 and 4, with
a mean of 16.

The path projection for this weekend is for Saturday, from San
Francisco, California.

To Europe, 80 meters 0030-0830z, 40 meters 2300-1000z (strongest
0130-0600z), 30 meters all hours, best 0200-0600z, weakest
1630-1930z, 20 meters 1400-2000z, 17 meters 1530-1930z, 15 meters
1600-1830z, 12 meters possibly 1700-1800z.

To Southern Africa, 80 meters 0100-0400z, 40 meters 0000-0430z, 30
meters 2300-0500z, 20 meters 2130-0400z, 17 meters 1800-0030z
(stronger later in the period, 15 meters 1630-2330z, 12 meters
1600-2230z, 10 meters 1700-2100z.

To the Caribbean, 80 meters 0030-1130z (best 0330-0930z), 40 meters
2330-1200z (best 0200-1000z), 30 meters 2230-1300z (best
0130-1000z), 20 meters open all hours except 1230-1330z, strongest
0130-0530z, 17 meters 1400-0100z, 15 meters 1430-0000z, 12 meters
1500-2300z, 10 meters 1530-2200z.

To South America, 80 meters 0100-1000z, 40 meters 0030-1030z, 30
meters 0000-1100z, 20 meters 2230-1030z (best 0130-0900z), 17 meters
2130-0600z, 15 meters 1400-0230z, 12 meters 1430-0200z, 10 meters
1530-0100z.

To Australia, 80 meters 0900-1500z, 40 meters 0830-1530z, 30 meters
0800-1600z, 20 meters 0700-1730z (best 0900-1430z), 17 meters around
1530z and 1900z, and 0630-0800z, 15 meters around 2000z and
0330-0430z, 12 meters 2100-0330z, 10 meters 2230-0230z.

To Japan, 80 meters 0700-1530z (best 0900-1000z), 40 meters
0630-1600z, 30 meters 0530-1700z (best 0830-1400z), 20 meters
1500-1800z and 0100-0730z, 17 meters 2030-0430z, 15 meters
2100-0330z, 12 meters 2130-0130z, 10 meters 2230-0030z.

To Hawaii, 80 meters 0300-1530z (best 0530-1330z), 40 meters
0130-1730z (best 0430-1400z), 30 meters all hours, best 0430- 1400z,
weakest 1930-2230z, 20 meters 1630-0400z, stronger toward the end of
the period, 17 meters 1700-0330z, 15 meters 1730-0200z, 12 meters
1830-0030z, 10 meters 1930-2300z.
NNNN
/EX