ARRL

ARRL Propagation Bulletin ARLP051 (1999)

SB PROP @ ARL $ARLP051
ARLP051 Propagation de K7VVV

ZCZC AP51
QST de W1AW  
Propagation Forecast Bulletin 51  ARLP051
From Tad Cook, K7VVV
Seattle, WA  December 17, 1999
To all radio amateurs 

SB PROP ARL ARLP051
ARLP051 Propagation de K7VVV

Solar flux and sunspot numbers rose over the past week after
declining for the previous few weeks.  Average solar flux was up
over 14 points compared to the previous week, and average sunspot
numbers were up nearly 34 points.  The only unstable geomagnetic day
was Monday, when the planetary A index was 26.  The K index was 4 or
5 for most of the day.  In Alaska, the higher latitude College A
index was 43, and the K index reached 6 over several three-hour
periods.

On Wednesday and Thursday of this week, just before this bulletin
was written, the solar flux was still rising.  There are actually
three solar flux readings taken every day at the Penticton, British
Columbia observatory, although the noon value is the one that is
reported as the official number for the day.  The thrice-daily
values for both days were 174.9, 178.7, 182.3, 191.6, 194, and 195.
This weekend look for the flux to peak, with Friday through Sunday
values around 200, 210 and 195.  Geomagnetic conditions should be
stable, with planetary A indices around 5, 8 and 10.

Check out a fascinating article from NASA on the web at
http://science.nasa.gov/newhome/headlines/ast16dec99_1.htm
concerning the lackluster numbers in the current solar cycle.  While
not making any prediction that we are headed for one, the article
talks about the Maunder Minimum, a time long before the use of radio
when there were no observed sunspots for about 70 years.  This is
used to illustrate the point that solar activity is highly variable.

Also see the January 2000 issue of QST for an article by ON4UN on
propagation during a solar eclipse last August.

There was an interesting wire service story this week from the
annual meeting of the American Geophysical Union in San Francisco
concerning a solar non-event on May 10-12 when there was no
detectable solar wind.  The density of the wind was only two percent
of normal, and without the wind to compress it, the earth's magnetic
field expanded out to nearly a quarter-million miles.  This event
was connected to the unusual difference between the southern and
northern auroral zones on May 11 mentioned in Propagation Forecast
Bulletin ARLP020 from May 14.

Sunspot numbers for December 9 through 15 were 132, 130, 134, 97,
147, 139 and 148 with a mean of 132.4. 10.7 cm flux was 156.2,
164.4, 159.1, 159.2, 166.1, 168.4 and 178.7, with a mean of 164.6,
and estimated planetary A indices were 12, 7, 7, 9, 26, 3 and 4,
with a mean of 9.7.

Here is a path projection for this weekend from Pittsburgh,
Pennsylvania.

To Europe, 80 meters 2030-1000z (peaking 0000-0700z), 40 meters
1900-1200z (best 2230-0730z), 30 meters 1200-0930z (best
2200-0800z), 20 meters 1200-2130z, 17 meters 1300-2030z, 15 meters
1330-1930z, 12 meters 1400-1900z, 10 meters 1430-1830z.

To Southern Africa, 80 meters 2130-0400z, 40 meters 2100-0430z, 30
meters 2030-0500z, 20 meters 1830-0000z and around 0530-0600z, 17
meters 1630-2300z, 15 meters 1600-2230z, 12 meters 1230-2130z, 10
meters 1300-2100z.

To South America, 80 meters 2300-0930z, 40 meters 2230-1030z, 30
meters 2200-1100z, 20 meters 2030-0800z and around 1130z, 17 meters
1230-0100z, 15 meters 1200-0030z, 12 meters 1230-0000z, 10 meters
1230-2300z.

To the Caribbean, 80 meters 2130-1200z, 40 meters open all hours,
strongest 2300-1030z, weakest 1500-1830z, 30 meters open all hours,
strongest 2230-0830z, weakest 1500-1830z, 20 meters 1130-0100z, 17
meters 1200-0000z, 15 meters 1230-2330z, 12 meters 1300-2230z, 10
meters 1300-2200z.

To Australia, 80 meters 0930-1330z, 40 meters 0900-1400z, 30 meters
0800-1500z, 20 meters 1330-1600z, 17 meters 1400-1830z, 15 meters
1430-1900z, 12 meters 1500-2000z, 10 meters 1530-1700z and
2100-2330z.

To Japan, 80 meters 0630-1400z, 40 meters 0530-1530z, 30 meters open
all hours, strongest 0800-1230z, weakest 0000-0330z, 20 meters
2030-0200z and 0330-1000z, 17 meters 2100-0100z, 15 meters
2130-2330z, 12 meters 2200-2300z, 10 meters 2200-2230z.

To Hawaii, 80 meters 0300-1400z (best 0630-1200z), 40 meters
0130-1500z (best 0430-1230z), 30 meters 0030-1530z (best
0400-1230z), 20 meters 1600-2000z and 2300-0400z, 17 meters
1600-0230z, 15 meters 1630-0130z, 12 meters 1630-0030z, 10 meters
1700-0000z.
NNNN
/EX