ARRL

ARRL Propagation Bulletin ARLP044 (1998)

SB PROP @ ARL $ARLP044
ARLP044 Propagation de K7VVV

ZCZC AP44
QST de W1AW  
Propagation Forecast Bulletin 44  ARLP044
From Tad Cook, K7VVV
Seattle, WA  October 30, 1998
To all radio amateurs 

SB PROP ARL ARLP044
ARLP044 Propagation de K7VVV

Solar activity was sharply lower last week.  Average sunspot numbers
dropped by well over half and average solar flux declined over 17
points to around 109.  This seems to be cyclical though, since the
average solar flux was down to the same level four weeks ago,
roughly corresponding to the rotation of the sun.  Average solar
flux for the previous ninety days declined this week from 132 to
131, and the solar flux values were far below this value on every
day of the past week.

Conditions were fair for the DX contest last weekend, and although
solar activity was low, there was quite a bit of activity on 10
meters where the author of this bulletin operated mobile.  An old
IC730--unused since the previous solar cycle--was dusted off, placed
in the car, and when hooked to a quarter wave trunk mounted whip.
It was clear that 10 meters was back.  Here on the west coast it was
fascinating to observe the propagation following the sun, with many
contacts to JA, VK and ZL around sunset.

KH6BZF sent a note on October 28 proposing that perhaps we have
passed a temporary lull in solar activity, and to support this idea
he noted several solar flux readings from the observatory in
Penticton, British Columbia.  These readings are taken three times
per day, at 9:00 AM, Noon and 3:00 PM local time, although it is the
noon measurement that is used for the official solar flux number for
the day.  The twelve consecutive solar flux readings for October 26
through 29 were 104.8, 104.1, 104.9, 101.7, 103, 103.8, 104.8,
107.8, 108.1, 109.7, 109.5 and 112.9.  You can check the progression
yourself on the web at Cary Oler's Solar Terrestrial Dispatch page
at http://holly.cc.uleth.ca/solar/index, then click on "Solar
Activity" in the left frame, then "10.7 cm Solar Radio Flux."

The predicted solar flux for this Friday through Sunday is 115, 115
and 120, and the projected planetary A index is 10, 8 and 8.  This
should mean slightly better conditions for the BARTG RTTY Contest
this weekend compared to the CQ World Wide DX Phone Contest last
weekend.

Look for unsettled geomagnetic conditions around November 3, and
again from November 16-21, due to recurring coronal holes.  Solar
flux should remain above 120 through November 13, then retreat to
110 by November 20.  This is all based on the previous solar
rotation, so with luck perhaps some unseen new activity will rotate
into view, improving HF propagation.

Radio Netherlands has a great collection of propagation web links.

See them at http://www.rnw.nl/realradio/propagation.html.

Sunspot Numbers for October 22 through 28 were 60, 71, 43, 49, 50,
17 and 33 with a mean of 46.1.  10.7 cm flux was 114.9, 112.5,
110.9, 107.5, 104.1, 103 and 107.8, with a mean of 108.7, and
estimated planetary A indices were 18, 13, 13, 16, 7, 6 and 12, with
a mean of 12.1.
NNNN
/EX