ARRL

ARRL Propagation Bulletin ARLP017 (1999)

SB PROP @ ARL $ARLP017
ARLP017 Propagation de K7VVV

ZCZC AP17
QST de W1AW  
Propagation Forecast Bulletin 17  ARLP017
From Tad Cook, K7VVV
Seattle, WA  April 23, 1999
To all radio amateurs 

SB PROP ARL ARLP017
ARLP017 Propagation de K7VVV

This was another down week for sunspots and solar flux, although
with the flares and associated geomagnetic activity, we can't say
that solar activity was down.  On Saturday the planetary A index
reached 47 with the K index as high as 7, an indication of a severe
geomagnetic storm.  This was caused by a coronal mass ejection,
another name for a solar flare.  Conditions were again unsettled to
minor storm a few days later when the planetary A index was 21.

K0XY wrote to complain about the solar flux, and with all of the
recent mail expressing fear that this cycle has already peaked, I
decided to check with a forecaster at the NOAH Space Environment
Center in Colorado.  They are still sticking with their forecast
made last year, that the peak of cycle 23 is probably a year from
now, or perhaps it will peak at the end of 2000.  It is important to
keep in mind that when looking at past solar cycles, we are often
observing smoothed numbers, and in fact there are often periods
before a cycle reaches a peak when there will be a lull in activity.
There is also a possibility that this cycle could be like cycle 22,
which had a broad double peak.

It should be noted that while radio amateurs often hope for high
solar activity, most of the individuals and organizations contacting
the Space Environment Center with concerns about solar activity do
not.  These are the folks who are working with satellites, power
distribution systems and pipelines, and worry about the sun
bombarding the earth with energy during high flare activity.

Look for a flat solar flux this week, with the numbers remaining
around 105.  The planetary A index for the weekend, Friday through
Sunday, should be 7, 7 and 10.  Don't expect the solar flux to
increase until after the end of April, with 130 by May 2, 140 by May
4, but then drifting back to 120 by May 12.  Of course, as always,
these projections are only based upon activity seen during the last
rotation of the sun, so new sunspots could appear and liven things
up.

Sunspot Numbers for April 15 through 21 were 95, 87, 99, 98, 90, 79
and 79 with a mean of 89.6.  10.7 cm flux was 121.8, 122.9, 115.7,
112.8, 110, 104.8 and 103.4, with a mean of 113.1, and estimated
planetary A indices were 4, 14, 47, 6, 13, 21 and 12, with a mean of
16.7.

The path projection for this weekend is from Alaska, somewhere
between Anchorage and Fairbanks:

To the geographic center of the contiguous 48 states of the U.S., 80
meters 0330-1230z, 40 meters 0130-1400z, 30 meters 1530-0830z and
1230-1400z, 20 meters 1630-0600z, and possibly 17 meters 1900-0200z.

To Western Europe, 40 meters 0330-0600z, 30 meters 0400-1030z and
1700-0100z, 20 meters 0600-0830z and 1500-0000z, 17 meters possibly
1830-2300z.

To Eastern Europe, 30 meters 0230-0700z and 1300-2300z, 20 meters
0330-0800z and 1530-2130z, 17 meters possibly around 0600z or
1830-2100z.

To Southern Africa, 20 meters 0400-0530z and 1500-0100z, 17 meters
2200-0000z and around 0430z.

To the Caribbean, 80 meters 0400-1000z, 40 meters 0230-1030z, 30
meters 0030-1100z, 20 meters 1730-0530z, 17 meters 1930-0100z, 15
meters possibly 2030-0100z,

To South America, 80 meters 0400-1000z, 40 meters 0300-1030z, 30
meters 0130-1030z, 20 meters 2230-0800z, 17 meters 2000-0430z, 15
meters 2130-2300z.

To Hawaii, 80 meters 0530-1500z, 40 meters 0400-1700z, 30 meters all
hours, with worst periods 1300z and 2130-2300z, 20 meters 1600-1930z
and 2300-0930z, 17 meters 2200-0430z, 15 meters possibly 2330-0200z.

To the South Pacific, 80 meters 0600-1500z, 40 meters 0530-1600z, 30
meters 0430- 1700z, 20 meters around 1530z and then 1700-2030z and
0200-1100z, 17 meters 1800-2130z and 0100-0900z, 15 meters
2200-0430z.

To Australia, 80 meters 0800-1530z, 40 meters 0730-1630z, 30 meters
0630-1730z, 20 meters 0500-1130z and again around 1600z, 17 meters
2030-0830z, 15 meters 0000- 0430z.

To Japan, 80 meters 0900-1630z, 40 meters 0730-1830z, 30 meters
0600-2100z, 20 meters 1800- 1130z, 17 meters 2230-0800z, 15 meters
possibly 2230-0330z.

To Central Asia, 80 meters around 1430z, 40 meters 1330-1700z, 30
meters 1200-2100z, 20 meters 1630-2000z, 2330-0500z, 0830-0900z and
1130-1200z, 17 meters 0000- 0530z, 15 meters possibly 0030-0200z.
NNNN
/EX