QST de W1AW
Propagation Forecast Bulletin 7 ARLP007
From Tad Cook, K7VVV
Seattle, WA February 14, 2003
To all radio amateurs
SB PROP ARL ARLP007
ARLP007 Propagation de K7VVV
Solar flux and sunspot numbers rose this week over last. Average daily sunspot numbers were up nearly 70 points and average daily solar flux rose by over 11 points. Neither number was rising over the past few days, and both are expected to continue to decline. The predicted solar flux for Friday through Monday is 130, 130, 125 and 125.
Solar flux is expected to reach a short-term minimum near 115 around February 21-22, and then reach another peak roughly around March 5-9. Don't expect high values like the past few years though. For example, during this same week last year the average daily solar flux was nearly 62 points higher at 201.8.
For the ARRL International DX CW Contest this weekend we could see some unsettled or perhaps active geomagnetic conditions. The earth should be inside a solar wind stream flowing from a coronal hole on Friday and Saturday. But the current prediction is for a planetary A index of only 15 over the weekend. No doubt higher latitude A indices could be higher.
For more information about propagation and an explanation of the numbers used in this bulletin, see the Propagation page on the ARRL Web site at, http://www.arrl.org/tis/info/propagation.html and, especially, the article "The Sun, the Earth, the Ionosphere," by Carl Luetzelschwab, K9LA.
Sunspot numbers for February 6 through 12 were 135, 153, 162, 194, 163, 134, and 119, with a mean of 151.4. 10.7 cm flux was 149.5, 147.3, 139.2, 141.4, 136.2, 134.9, and 131.6, with a mean of 140. Estimated planetary A indices were 16, 13, 13, 15, 16, 12, and 12, with a mean of 13.9.