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ARRL Propagation Bulletin ARLP005 (2000)

ARLP005 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7VVV
Seattle, WA  February 4, 2000
To all radio amateurs 

ARLP005 Propagation de K7VVV

Average solar flux and sunspot numbers were down over the past week,
and geomagnetic indices were about the same as the week before.
Average solar flux was down over 10 points to 138, and average
sunspot numbers were off over 36 points to 99.

As projected in last week's Propagation Forecast Bulletin ARLP004,
geomagnetic indices were active last weekend, with planetary A index
for Friday through Sunday of 29, 25 and 11, compared to the
predicted values of 25, 25 and 18.  Planetary K index values were as
high as 5 on Friday and Saturday, and the College K index, based in
Alaska, was as high as 7, which indicates a severe geomagnetic

For this weekend, expect moderate planetary A indices of 7, 7 and 10
for Friday through Sunday, rising to 15 on Monday.  Geomagnetic
indices should stay moderate until February 23-26, when the
planetary A index could reach 20.

Predicted solar flux for Friday through Sunday is 155, 170 and 180,
rising to 190 on Monday, 195 on Tuesday, and peaking around 205 on
February 11-12.  Solar flux is expected to drop below 150 again
after February 18, and bottom out around 130 from February 23-25.
There should be another solar flux peak around March 9-10, based on
the rotation of the sun, which happens about every 27 days relative
to earth.

Where are we now in the current cycle?  A year ago this bulletin
reported an average solar flux of 123.9 and 153.9 for the week
previous.  The average solar flux for the month of January was 159,
for December was 169.8 and November was 191.5.  The latest
prediction from NOAA shows the peak flux value of the current solar
cycle coming up in August of this year, but the value is only about
17 points higher than the monthly average forecast for this month.

W0NXS sent an interesting article from the Jet Propulsion Laboratory
at the California Institute of Technology concerning repeatability
in periods of solar magnetic fields.  The article spoke of research
which observed data over 38 years, and concluded that variations in
solar magnetic fields repeat every 27 days and 43 minutes.  The
findings were published in the February 1 issue of the Journal of
Geophysical Research.  Additional information is at

Another interesting article appears at the NASA Space Science News
site at
This shows some dramatic pictures from the Solar and Heliospheric
Observatory detailing huge coronal mass ejections from the sun over
the past week.

Sunspot numbers for January 27 through February 2 were 110, 96, 81,
90, 82, 107 and 127 with a mean of 99.  10.7 cm flux was 132.4, 152,
127.7, 132.7, 138.6, 138.1 and 144.4, with a mean of 138, and
estimated planetary A indices were 12, 29, 25, 11, 6, 8 and 7, with
a mean of 14.

This week's path projection will be from the center of the
contiguous 48 U.S. states for Saturday, February 5.

To Western Europe, 80 meters 2230-0930z (best 0230-0630z), 40 meters
2130-1100z (best 0030-0730z), 30 meters 2000-1230z (best
0000-0730z), 20 meters 1400-0030z, 17 meters 1400-2130z, 15 meters
1430-2030z, 12 meters 1500-1900z, 10 meters 1600-1830z.

To Eastern Europe, 80 meters 2330-0700z, 40 meters 2230-0800z, 30
meters 2130-0930z, 20 meters 1400-1530z and 1900-2100z, 17 meters
1430-1830z, 15 meters 1500-1730z, 12 meters 1600-1630z.

To Southern Africa, 80 meters 2330-0430z, 40 and 30 meters 2230-
0500z, 20 meters 2200-0300z, 17 meters 1930-0030z, 15 meters
1830-2330z, 12 meters 1800-2200z, 10 meters 1830-2130z.

To South America, 80 meters 0000-1000z (best 0230-0900z), 40 meters
2330-1000z (best 0030-0900z), 30 meters 2330-1100z (best
0030-0930z), 20 meters 2200-0930z, 17 meters 1300-1400z and
2100-0200z, 15 meters 1400-0100z (strongest later in the period), 12
meters 1430-0030z, 10 meters 1500-2230z.

To the Caribbean, 80 meters 2330-1200z (best 0130-1030z), 40 meters
2200-1330z (best 0030-1030z), 30 meters all hours, best 0030-1030z,
weakest 1530-1930z, 20 meters 1330-0100z, 17 meters 1400-0000z, 15
meters 1430-2300z, 12 meters 1530- 2130z, 10 meters 1630-2030z.

To Australia, 80 meters 0930-1400z, 40 meters 0930-1500z, 30 meters
0900-1500z, 20 meters 0830-1200z and 1400-1600z, 17 meters
1500-1700z, 15 meters 1530-1700z.

To Japan, 80 meters 0730-1400z, 40 meters 0700-1500z, 30 meters
0630-1600z, 20 meters 1430-1730z, 17 meters 2100-0300z, 15 meters
2130-0200z, 12 meters 2200-0030z, 10 meters 2200-2330z.


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