ARLP010 Propagation de K7VVV:
March 10, 2000

Propagation Forecast Bulletin 10 ARLP010
From Tad Cook, K7VVV
Seattle, WA March 10, 2000
To all radio amateurs

ARLP010 Propagation de K7VVV

There was a nice surprise for participants in last weekend's DX contest. ARLB009 predicted stormy geomagnetic conditions, but it turned out that the energy from solar eruptions did not affect the earth's geomagnetic field. Instead of the predicted planetary A indices of 12, 28 and 25 for Friday through Sunday, the A index for those days was 5, 5 and 7, which is very quiet. Solar flux was 189, 167 and 181.

Average solar flux was about the same last week as the week before, and average sunspot numbers were slightly lower. Average A indices have also been lower.

Solar flux is expected to dip below 200 this weekend. Predicted flux values for Friday through Tuesday are 200, 195, 190, 185 and 180. Solar flux is expected to bottom out around 150 on March 17 or 18, then rise above 200 by March 23 and stay around 220 from March 25 to April 4.

Geomagnetic indices are expected to remain quiet until March 22-23, then settle down again until March 31 and April 1.

We are moving toward the spring equinox, which always means better HF conditions, especially with the rising solar flux. Look for more frequent worldwide openings on 10, 12 and 15 meters.

Cable News Network has an email service which delivers weekly space news, and some of it concerns solar activity of interest to hams. The email service sends URL links to articles, such as the one at You can subscribe at

In the mail this week was an interesting tip from a ham in Vermont, who wrote, "This is Zach Manganello, K1ZK, I am a freshman at Middlebury College, and I just attended a lecture that I thought was absolutely fascinating, pertinent to HF propagation, and worthy of sharing with you at the ARRL. The lecture was about the Super Dual Auroral Radar Network (SuperDARN), and these scientists have giant radar arrays at several locations near the Earth's poles which they use to study interaction of solar radiation with the Earth's geosphere and ionosphere. Check out their web site at".

NASA Space Science News has an item this week about predicting disturbances by seeing what is happening on the other side of the sun that faces away from earth. This uses the Michelson Doppler Imager on the Solar and Heliospheric Observatory, on the web at This is important because solar forecasts for the short term are based on calculating when known active regions will rotate back into view. If activity can be observed on the far side of the sun, then more accurate forecasts can be made which are not dependent on the last glimpse of the active region before it rotated out of view.

Finally, check out, a site devoted to this year's peak in solar activity.

Sunspot numbers for March 2 through 8 were 209, 189, 167, 181, 172, 164 and 212 with a mean of 184.9. 10.7 cm flux was 213.2 203.8, 200.2, 220.3, 222.4, 221.8 and 214.9, with a mean of 213.8, and estimated planetary A indices were 8, 5, 5, 7, 11, 16 and 13, with a mean of 9.3.

The path projection for this week is from Middlebury, Vermont.