ARRL

ARRL Propagation Bulletin ARLP040 (1999)

SB PROP @ ARL $ARLP040
ARLP040 Propagation de K7VVV

ZCZC AP40
QST de W1AW  
Propagation Forecast Bulletin 40  ARLP040
From Tad Cook, K7VVV
Seattle, WA  October 4, 1999
To all radio amateurs 

SB PROP ARL ARLP040
ARLP040 Propagation de K7VVV

There was a delay in putting out the bulletin this week due to an
unannounced change in servers at the Penticton Observatory.  This
delayed getting some of the data for this bulletin.

Last week, which we report as Thursday through Wednesday, we saw
marginal HF conditions and a declining solar flux.  The average
sunspot number was down over 56 points and average solar flux was
off by over 22 points compared to the previous week.  The really
active geomagnetic day was September 27, when the planetary A index
was 37 and the highest planetary K index was 5.  The higher
latitudes had the worst conditions, with the College A index from
Alaska at 66 for the day with the K index up to 7.

Solar flux probably bottomed out on Friday, October 1 at 121.6.  It
has been rising since then, and two days later on October 3 it was
141.3 for the morning reading at Penticton and 134.5 for the noon
reading, which is the official number for the day.

The predicted solar flux for the next week, beginning Monday,
October 4 is 138, 140, 142, 145, 148, 150 and 152.  Unless new
activity appears, solar flux will probably peak above 155 around the
middle of the month.  Predicted planetary A index for the same
period is 15, 12, 12, 12, 10, 15 and 15.  These predictions which go
out a week are fairly rough beyond the first few days.

The beginning of October marks the end of the third quarter of the
calendar year.  Average solar flux for the month of September was
135.7, the lowest since April, when it was 117.2.  Average monthly
solar flux for May, June, July and August was 148.4, 169.8, 165.6
and 170.7.  Average solar flux for the first quarter of 1999 was
136.7, actually one point higher than it was for the month of
September and nine points higher than the average for last week.
Flux for the second quarter was 145, and for the quarter just ended
it was 157.6.  This indicates a steady upward trend for cycle 23,
although a peek at the graph at http://www.dxlc.com/solar/ looks
like recent trends over the last few solar rotations are down.  The
predicted peak for this cycle is some time next year.  You can see
charts of the forecast data in Acrobat format by scrolling to the
last few pages at http://www.sec.noaa.gov/weekly/pdf/prf1253.pdf.
Also check the page which leads to this report, which can be found
at http://www.sec.noaa.gov/weekly/index.html.  This has the weekly
NOAA SESC Preliminary Report and Forecast.

JA7SSB sent an interesting URL for a solar activity chart which is
very beautifully done with lots of rich detail.  You can see it at
http://crlgin.crl.go.jp/sedoss/solact3.

Sunspot numbers for September 23 through 29 were 78, 86, 38, 44, 49,
52 and 84 with a mean of 61.6.  10.7 cm flux was 136.9, 131.6,
125.4, 122.7, 123.8, 126 and 124.8, with a mean of 127.3, and
estimated planetary A indices were 24, 6, 4, 15, 37, 20 and 19, with
a mean of 17.9.

The path projection this time is for mid-week from St. Louis,
Missouri.

To Europe, 80 meters 2300-0800z, 40 meters 2100-0930z (peaking
0000-0600z), 30 meters 1930-1030z (peaking 2330-0630z), 20 meters
1130-0200z (peaking 2130-2330z), 17 meters 2130-2130z, 15 meters
1400-2030z, 12 meters 1530-1900z, 10 meters 1630-1900z.

To Southern Africa, 80 meters 2300-0430z, 40 meters 2200-0500z, 30
meters 2130-0530z, 20 meters 2030-0500z, 17 meters 1900-0100z, 15
meters 1600-0000z, 12 meters 1330-2230z, 10 meters 1400-2200z,
peaking around 2030z.

To the Caribbean, 80 meters 2230-1130z (peaking 0200-0930z), 40
meters 2030-1330z (peaking 0000-1000z), 30 meters all hours,
strongest 2330-1030z, weakest around 1630z, 20 meters all hours,
strongest 0000-1000z, weakest 1530-1830z, 17 meters 1130-0200z,
strongest late in the period, 15 meters 1200- 0100z, strongest late
in the period, 12 meters 1230-0000z, 10 meters 1300-2300z.

To South America, 80 meters 2330-1000z, 40 meters 2300-1000z, 30
meters 2230-1100z, 20 meters 2100-1200z, 17 meters 1200z-0200z
(strongest 2330-0100z), 15 meters 1230-0100z (strongest late in the
period), 12 meters 1300-2330z, 10 meters 1400-2300z.

To Australia, 80 meters 0730-1300z, 40 meters 0700-1300z, 30 meters
0630-1330z, 20 meters 0530-1500z, 17 meters 0500-0800z and
1300-1500z, 15 meters 0130-0330z, 12 meters 1930-0230z, 10 meters
2030-0200z.

To Japan, 80 meters 0800-1300z, 40 meters 0630-1300z, 30 meters
0530-1430z, 20 meters 1330-1800z and 0230 to 0400z, 17 meters
2000-0200z, 15 meters 2030-0200z, 12 meters 2100- 0030z, 10 meters
2130-2330z.

To Hawaii, 80 meters 0330-1330z (peaking 0700-1130z), 40 meters
0230-1400z (peaking 0500-1200z), 30 meters 0130-1500z (peaking
0430-1200z), 20 meters all hours, peaking 0400 1200z, weakest
1430-1530z and 2000-2100z, 17 meters 1530- 0430z, strongest toward
the end of the period, 15 meters 1600- 0300z, 12 meters 1700-0200z,
10 meters 1700-0130z.

To Alaska, 80 meters 0100-1300z (strongest 0400-0500z), 40 meters
2330-1430z (best 0330-1130z), 30 meters all hours, best 0400-0700 z,
weakest 1430-1530z and 1830-1930z, 20 meters 1500-0300z, strongest
toward the end of the period, 17 meters 1800-0130z, 15 meters
2000-2330z, 12 meters possibly 2100-2300z.
NNNN
/EX