ARRL

ARRL Propagation Bulletin ARLP036 (2000)

SB PROP @ ARL $ARLP036
ARLP036 Propagation de K7VVV

ZCZC AP36
QST de W1AW  
Propagation Forecast Bulletin 36  ARLP036
From Tad Cook, K7VVV
Seattle, WA  September 8, 2000
To all radio amateurs 

SB PROP ARL ARLP036
ARLP036 Propagation de K7VVV

Solar flux and sunspot numbers were up over the past week. Average
solar flux was up over 17 points and average sunspot numbers rose
over 40 when compared to the previous week. The peak in activity
didn't exactly coincide for the two indexes, with sunspot numbers
first reaching the peak at 214 early in the week. If you look at the
graphs at http://www.dxlc.com/solar/ you can see the two peaks, and
in fact from this chart it looks like the solar cycle may have
peaked in July.

So when will this solar cycle peak? NOAA has some new projections.
If you look at http://www.sec.noaa.gov/weekly/pdf/prf1305.pdf it
shows smoothed sunspot numbers peaking in December, 2000 at 140.
The predicted progression for smoothed sunspot numbers for August
2000 through June, 2001 is 136, 137, 138, 139, 140, 139, 138, 139,
138, 137 and 136.

A similar table for smoothed 10.7 cm solar flux shows the predicted
peak around March, 2001 at 189. The predicted progression for
smoothed solar flux for August 2000 through June, 2001 is 187, 187,
186, 187, 187, 187, 187, 189, 188, 187 and 186.

All this is good news for hams hoping for a further peak in solar
activity. The best is yet to come, and we can look forward to
interesting activity this fall and next spring.

For this week, projections show solar flux peaking around now and
then dipping down to a short term minimum around September 21, with
the next peak around October 5.

NW7US wrote this week to tell us about his web site devoted to radio
propagation. It is at http://hfradio.org/propagation.html and
features a listserver where users can be automatically alerted
concerning changes in solar and geomagnetic conditions.

N7SO wrote to mention other solar web sites, including solar images
at http://umbra.nascom.nasa.gov/images/ . Another one to check out
is http://www.lpl.arizona.edu/~rhill/alpo/solstuff/recobs.html .
This has many fine images, although unless you have a broadband
internet hookup, the whole page takes a very long time to load.

Sunspot numbers for August 31 through September 6 were 214, 195,
177, 181, 169, 144 and 150 with a mean of 175.7. 10.7 cm flux was
162.9, 157.7, 154, 154.1, 170.8, 180.2 and 178.7, with a mean of
165.5, and estimated planetary A indices were 15, 17, 23, 9, 14, 8
and 11 with a mean of 13.9.
NNNN
/EX