QST de W1AW
Propagation Forecast Bulletin 3 ARLP003
From Tad Cook, K7VVV
Seattle, WA January 18, 2002
To all radio amateurs
SB PROP ARL ARLP003
ARLP003 Propagation de K7VVV
Last week's bulletin talked about a rising solar flux, with a peak around Thursday of this week. Instead the visible solar disk has few sunspots, and solar flux is almost 50 points lower than predicted. Geomagnetic conditions were unsettled last weekend, but not stormy. Instead of planetary A indices of 30, 20 and 15 for Friday through Sunday, they were 21, 15 and 11.
On Friday the planetary K index was at 4 most of the day. Higher latitude geomagnetic indices were greater. Alaska's College A index for Friday was 37, and the day prior was even higher at 45. The College K index went as high as 7 on Thursday, indicating a geomagnetic storm and absorption for radio signals traveling over the polar path.
Average daily solar flux was about 18 points higher than the previous week, and average daily sunspot numbers were over 9 points lower.
The latest prediction for the next few days shows no geomagnetic upsets, with solar flux at 215 for Friday and Saturday and 220 for Sunday. Projected average solar flux for the whole week looks to be similar to this week, unless some new sunspots emerge. Holographic images of the sun's far side show a large active region, but it won't face the earth until some time after next week.
WA4TTK has some minor revisions to his Solar Data Plotting Utility, including the ability to download data in one file from the ARRL. Get the latest version from Scott on his web site at http://www.craigcentral.com/sol.htm .
AC7OT in Tucson asked about web sites that feature geophysical data. As mentioned last week, gopher://solar.sec.noaa.gov/00/latest/DGD gives A and K indices for middle latitude, high latitude, and also planetary, which is for the entire earth.
You can see the latest text from the 18-minutes-after-each-hour WWV bulletin (which has the latest Boulder, Colorado K index) from NOAA at ftp://ftp.sel.noaa.gov/pub/latest/wwv.txt .
There is a good site with links concerning auroras, (which emerge during periods of high geomagnetic activity) at the University of Alaska at http://www.pfrr.alaska.edu/~pfrr/AURORA/LINKS.HTM .
There is lots of data from the National Geophysical Data Center at http://www.ngdc.noaa.gov/ , and there is a good explanation of the relationship between geomagnetic A and K indices at http://www.ngdc.noaa.gov/stp/GEOMAG/kp_ap.html .
Look for plots of solar-geophysical data at http://sec.noaa.gov/ftpmenu/plots.html , and then look toward the bottom for yearly plot files. If you click on the 2001 files, check out the period between March 31 and April 2. You will see some huge K index numbers during a tremendous geomagnetic storm. One file to look at is the one beginning with the characters 20010401.
Sunspot numbers for January 10 through 16 were 179, 195, 174, 190, 191, 155 and 131 with a mean of 173.6. 10.7 cm flux was 224.6, 228.9, 233.3, 240.7, 229, 218.3 and 216.1, with a mean of 227.3, and estimated planetary A indices were 17, 21, 15, 11, 8, 6 and 4 with a mean of 11.7.