ARRL

ARRL Propagation Bulletin ARLP018 (1999)

SB PROP @ ARL $ARLP018
ARLP018 Propagation de K7VVV

ZCZC AP18
QST de W1AW  
Propagation Forecast Bulletin 18  ARLP018
From Tad Cook, K7VVV
Seattle, WA  April 30, 1999
To all radio amateurs 

SB PROP ARL ARLP018
ARLP018 Propagation de K7VVV

Solar flux and sunspots were down again this week, although with
activity so low, it couldn't really drop very far.  Solar flux has
taken a jump in the past couple of days, with solar flux up about 20
points on Thursday compared to earlier in the week.  The predicted
solar flux for this weekend, Friday through Sunday is 125, 130 and
135, and the Planetary A index is predicted at 25, 30 and 30.  The
geomagnetic field has been active for the past few days due to
coronal holes, and this should continue.

Beyond the weekend, higher solar flux should continue, with values
around 140 or higher.  Solar flux is expected to drop down to around
125 again by May 11, and 110 a week later.

Jim Secan of Northwest Research Associates (www.nwra.com) wrote to
emphasize that when we notice this solar cycle in a stall, it is
important to keep in mind that when we are comparing it with past
cycles, we are often looking at smoothed charts with moving
averages.  Jim says that it is not at all unusual for a solar cycle
to stall like this, and in fact cycle 19 of the late 1950s, fondly
recalled by radio amateurs as the biggest solar cycle of all time,
did this as well.  Predicting solar cycles is based upon statistical
observations but without very many cycles to base it on.  Jim says
that the latest revised forecast from the NOAA Space Environment
Center puts the peak of the cycle probably around late 2000.  Since
the peak of any cycle is really spread over a couple of years,
fixing a particular season and year is probably not realistic.

I received a couple of nice notes from Shel Shallon, W6EL, author of
the popular Mini Prop propagation software, and from Orlando, KT4KF.
They both pointed out that solar flares and coronal mass ejections
are not the same.  A solar flare releases particles which may cause
a coronal mass ejection, and if it is strong enough, the ejection
can hit earth, which a flare never does.  Shel mentioned that a
coronal mass ejection may contain a billion tons of matter and
travel at several million miles per hour.  Coronal mass ejections
may also appear independently of flares.

K0FF wrote that on Wednesday he worked many South American stations
on six meters from Northeast Missouri.  This was during a period
when the geomagnetic conditions were unsettled, but not active or
stormy.

Sunspot Numbers for April 22 through 28 were 62, 71, 89, 69, 69, 82
and 76 with a mean of 74.  10.7 cm flux was 100.2, 98.2, 100.9,
102.6, 104.5, 108.6 and 109.8, with a mean of 103.5, and estimated
planetary A indices were 4, 5, 7, 5, 7, 14 and 19, with a mean of
8.7.

The path projection for this weekend is from Hawaii.

To Western Europe, 30 meters 0430-0630 UTC, 20 meters 0400-1500 UTC,
17 meters 0630-1130 UTC and 1430-2100 UTC, 15 meters around 1700
UTC.

To Eastern Europe, 20 meters 0400-1800 UTC, 17 meters 0500-1200 UTC,
1500-2000 UTC, and perhaps 15 meters around 0700-1130 UTC or
1530-1900 UTC.

To Southern Africa, 40 meters 1530-1630 UTC, 30 meters 1430-1700
UTC, 20 meters 1330-1830 UTC, 17 meters 1200-2100 UTC, 15 meters
0900-1230 UTC and 1700-2300 UTC, 17 meters 1900-2300 UTC and 0430-
1100 UTC, 10 meters 0430-0900 UTC and 2030-2200 UTC.

To the Caribbean, 80 meters 0430-1030 UTC, 40 meters 0300-1100 UTC,
30 meters 0230-1230 UTC, 20 meters 0030-1430 UTC, 17 meters all
hours, strongest signals 0430-0530 UTC, weakest 1430-1500 UTC, 15
meters 1530-0500 UTC, 12 meters 1700-0400 UTC, 10 meters 1830-2100
UTC.

To South America, 80 meters 0430-1100 UTC, 40 meters 0400-1130 UTC,
30 meters 0300-1200 UTC, 20 meters 0100-1400 UTC, 17 meters 1100-
1300 UTC and 1500-1700 UTC and 2200-0800 UTC, 15 meters 1600-0730
UTC, 12 meters 1630-0700 UTC, 10 meters 1730-0600 UTC.

To Alaska, 80 meters 0530-1500 UTC, 40 meters 0400-1630 UTC, 30
meters all hours, best signals 0730-1230 UTC, worst signals 2130-
2300 UTC, 20 meters 0000-1030 UTC and 1500-1930 UTC, 17 meters
2200-0630 UTC.

To the South Pacific, 80 meters 0500-1630 UTC, 40 meters 0330-1800
UTC, 30 meters all hours, best signals 0600-1530 UTC, worst signals
2200-2330 UTC, 20 meters 1700 UTC-1430 UTC, 17 meters 1730-1100 UTC,
15 meters 1800-0900 UTC, 12 meters 1830-0630 UTC, 10 meters
2000-0530 UTC.

To Australia, 80 meters 0700-1630 UTC, 40 meters 0630-1700 UTC, 30
meters 0530-1800 UTC, 20 meters all hours, strongest signals 0800-
1500 UTC, weakest 2330-0030 UTC, 17 meters 2030-0830 UTC, 15 meters
2100-0800 UTC, 12 meters 2130-0700 UTC, 10 meters 2200-0630 UTC.

To Japan, 80 meters 0900-1630 UTC, 40 meters 0730-1730 UTC, 30
meters 0600-1900 UTC, 20 meters all hours, best signals 0930-1600
UTC, weakest 2330 UTC, 17 meters all hours, strongest 1000-1300 UTC,
weakest 2300-0200 UTC, 15 meters 1930-1230 UTC, 12 meters 2100-1100
UTC, 10 meters 2230-1000 UTC.

To Central Asia (India), 80 meters 1330-1600 UTC, 40 meters 1230-
1630 UTC, 30 meters 1200-1730 UTC, 20 meters 0930-1930 UTC, 17
meters 0700-1330 UTC and 1500-2030 UTC, 15 meters 0000-1200 UTC and
1700-1900 UTC, 12 meters 0130-1030 UTC, 10 meters 0300-0900 UTC.
NNNN
/EX