ARRL

ARRL Propagation Bulletin ARLP050 (1996)

SB PROP @ ARL $ARLP050
ARLP050 Propagation de KT7H

ZCZC AP70
QST de W1AW
Propagation Forecast Bulletin 50  ARLP050
From Tad Cook, KT7H
Seattle, WA  November 30, 1996
To all radio amateurs

SB PROP ARL ARLP050
ARLP050 Propagation de KT7H

What an exciting week for propagation.  Solar activity took an
unexpected leap over the past week, rising to levels not observed in
over two years.  We have not seen solar flux at 100 since September
3, 1994 and when it reached 104.4 on November 25, the solar flux had
not been that high since February 24, 1994.

It is uncertain what this activity has to do with ushering in cycle
23, since the sunspots producing these numbers were around the Sun's
equator, and new cycle regions are associated with higher latitudes.

The average flux was up more than 20 points above the previous week,
while sunspot numbers were up over 35 points and the A index was
down over 4 points.

The current forecast is for flux values to go below 90 around
December 5, a minimum of 72 from December 7 through 16, and above 90
again after December 21.  This is based on the previous solar
rotation, so really anything could happen.  This is merely a
forecast that tries to predict what will happen when the solar
regions that caused the current activity rotate into view again.

We had several comments via email during the past week.  Don Stoner,
W6TNS commented that current conditions don't reflect what his
logbook shows for 1994.  This is probably because we haven't had a
sustained period of higher solar activity.

Several people, including W7LKR said that conditions on 80 meters
were quite odd, with absorption up normal communications to regional
stations difficult.

Readers who wish to contact the author of this bulletin can reach me
via email at tad@ssc.com.  For packet radio users the address is
KT7H @ N7DUO.#WWA.WA.USA.NOAM.

The flux numbers given in this weekly bulletin are always the noon
measurements from the Penticton, BC observatory, but there are
actually three per day.  Below is a table of each flux value for
every day since the last bulletin:

11/21/96 1800 UTC: 74.2
11/21/96 2000 UTC: 74.4
11/21/96 2200 UTC: 75.5

11/22/96 1800 UTC: 79.5
11/22/96 2000 UTC: 82.6
11/22/96 2200 UTC: 82.3

11/23/96 2200 UTC: 95.0
11/23/96 2000 UTC: 91.0
11/23/96 1800 UTC: 90.6

11/24/96 1800 UTC: 103.5
11/24/96 2000 UTC: 99.8
11/24/96 2200 UTC: 104.2

11/25/96 1800 UTC: 103.6
11/25/96 2000 UTC: 104.4
11/25/96 2200 UTC: 102.1

11/26/96 1800 UTC: 104.0
11/26/96 2000 UTC: 103.6
11/26/96 2200 UTC: 106.1

11/27/96 1800 UTC: 99.6
11/27/96 2000 UTC: 102.7
11/27/96 2200 UTC: 100.7

11/28/96 1800 UTC: 96.1
11/28/96 2000 UTC: 98.1
11/28/96 2200 UTC: 97.5

Thanks to Cary Oler for the above data.  Cary has a very interesting
and informative web page with solar data and current solar images at
http://holly.cc.uleth.ca/solar/index.html

Sunspot Numbers for November 21 through 27 were 26, 27, 73, 54, 89,
85 and 63, with a mean of 59.6.  10.7 cm flux was 74.4, 82.6, 91,
99.8, 104.4, 103.6 and 102.7, with a mean of 94.1.  Planetary A
indices for the same period were 5, 3, 3, 8, 4, 4, and 8, with a
mean of 5.

NNNN
/EX