QST de W1AW
Propagation Forecast Bulletin 36 ARLP036
From Tad Cook, K7VVV
Seattle, WA August 30, 2002
To all radio amateurs
SB PROP ARL ARLP036
ARLP036 Propagation de K7VVV
Last week's rise in sunspot count couldn't last forever, and the numbers this week show a drop. Average daily sunspot count for the week of August 22-28 (Thursday through Wednesday, for the convenience of this bulletin schedule) declined 104 points, and solar flux was down by nearly 38 points when compared to the previous week.
Paul Gili, AA1LL, in New Hampshire wrote to ask if the renewed activity meant that there might be a third peak to Cycle 23. I don't think so, but this is just based on observations of past cycles. I don't know of any way to really predict it, except that it would be outside the standard variation for a sunspot cycle. You can visualize the shape of past cycles from 1700 to present using the Historical Solar Charts on the WM7D.net site.
David Bernstein, AA6YQ, in Massachusetts asks us to check out PropView, a very interesting free program that is a graphical front end for IONCAP (Ionospheric Communications Analysis Prediction). It's available on the PropView Web site. Another program, DXView can be used with PropView to automate the selection of targets, as well as control antenna rotators. PropView can be used with the NCDXF beacons to compare predictions with actual on the air observations. This also works with SpotCollector, which gathers data from local PacketCluster networks, the DX Summit spotting network and up to four additional telnet- accessible DX clusters. You can get these and additional software that works with PropView from the DX Lab Web site.
A pair of NOAA links for solar and geomagnetic data listings mentioned here in the past--and the source for two-thirds of the data appearing at the end of each bulletins--have moved. Occasionally NOAA moves these to another server, and then the old links don't work. The new URLs that do work are http://www.sec.noaa.gov/ftpdir/indices/DGD.txt for geomagnetic indices and http://www.sec.noaa.gov/ftpdir/indices/DSD.txt for solar data. The other one-third of the data at the bottom of these bulletins is from Canada's Dominion Radio Astrophysical Observatory. The flux values presented here are the 2000 UTC daily measurements from the Observed column. 2000 UTC is local noon in Penticton, British Columbia, the location of the observatory.
The autumnal equinox is just a few weeks away. This is a great time for HF DX, as we pass from the summer season. Sunspot 87 is currently passing through an area where it is squarely aimed at earth and poses a threat for developing powerful X-class solar flares. The current prediction is for moderate to unsettled geomagnetic activity over the next few days, barring any upset from sunspot 87. Solar flux is expected to decline over the next few days with Friday through Monday values around 170, 165, 155, and 150. Solar flux is expected to reach a near term minimum near 125 around September 7, and then bounce back quickly.
Sunspot numbers for August 15 through 21 were 281, 247, 270, 308, 247, 209 and 238, with a mean of 257.1. The 10.7-cm flux was 210.3, 213.8, 226.7, 241, 237, 227.5 and 219.9, with a mean of 225.2. Estimated planetary A indices were 19, 17, 13, 18, 27, 23 and 41, with a mean of 22.6.
Sunspot numbers for August 22 through 28 were 205, 207, 199, 136, 105, 133 and 87, with a mean of 153.1. The 10.7-cm flux was 220.1, 224.5, 195.6, 178.6, 168.6, 161.4, and 163.2, with a mean of 187.4. Estimated planetary A indices were 11, 11, 11, 9, 18, 15 and 10, with a mean of 12.1.