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.