QST de W1AW
Propagation Forecast Bulletin 22 ARLP022
From Tad Cook, K7VVV
Seattle, WA June 2, 2000
To all radio amateurs
SB PROP ARL ARLP022
ARLP022 Propagation de K7VVV
Average solar flux and sunspot numbers for last week were 158.3 and 152.7 respectively, which is down quite a bit from the week before. Average flux was off nearly 70 points and average sunspot numbers were down over 80 points when compared to the previous week. Contesters were lucky last weekend, as the planetary A index was 12 on Saturday and Sunday, but much higher on the days before and after the weekend. Polar paths were probably still difficult, as the high latitude A and K indices were still high on the weekend. For instance, while the planetary K index was two and three on Sunday, the College K index, measured at Fairbanks, Alaska was five and six, which is at storm levels.
Average solar flux for the month of May was 184.5, about the same as April, which was 184.2. Average monthly solar flux numbers from May, 1999 through May, 2000 were 147.8, 169.8, 165.6, 170.8, 135.7, 164.8, 191.5, 169.8, 159, 174.1, 208.2, 184.2 and 184.5.
For the next few days we should expect a rising solar flux. Predicted solar flux for Friday through Tuesday is 155, 160, 160, 165 and 165. Solar flux is expected to peak near 260 around June 12 or 13, based upon the previous solar rotation. Geomagnetic activity for the near term looks stable, with planetary A indices for Friday through Tuesday of 10, 8, 10, 10 and 10.
KV4AC wrote this week asking about the path projections and software for evaluating propagation. The one I have used is W6EL's Miniprop. Unfortunately, this DOS software is no longer published, and the latest version is no longer available. But an early 1987 shareware version is available for FTP, and it works quite well. It gives signal level predictions in 2 hour increments and only does five bands at a time, whereas later versions give levels in half-hour increments and will display seven frequencies at a time. One source for this version is a link on AE0Q's web page at http://www.qsl.net/ae0q/index.html.
This week, try doing your own path projections. You can check the current solar flux over the radio on WWV at 18 minutes after every hour, or dial 303-497-3235 at any time. Then after downloading Miniprop, put in your latitude and longitude for the default values, select a target, enter the letter F followed by the solar flux, and the date. You can find your exact latitude and longitude by entering your street address at www.mapblast.com. Select the Create Map option, and your coordinates will appear at the edge of the map. Take care when entering the coordinates into Miniprop, because the conventions between Mapblast and Miniprop are slightly different. In Miniprop, both coordinates for North American locations will be positive, whereas in Mapblast one is negative.
Notes to the author are welcome at email@example.com.
Sunspot numbers for May 25 through 31 were 125, 155, 161, 176, 189, 153 and 110 with a mean of 152.7. 10.7 cm flux was 172.8, 167.9, 161.8, 155.9, 149, 146.4 and 154.4, with a mean of 158.3, and estimated planetary A indices were 31, 23, 12, 12, 24, 21 and 12, with a mean of 19.3.