ZCZC AP13
QST de W1AW
Propagation Forecast Bulletin 13 ARLP013
From Tad Cook, K7VVV
Seattle, WA March 31, 2000
To all radio amateurs
SB PROP ARL ARLP013
ARLP013 Propagation de K7VVV
Last week's conditions for the CQ Worldwide WPX Phone contest turned out to be quite good. The predicted geomagnetic upset did not arrive. This is the second time recently that bad conditions were forecast for a contest weekend, and then the energy from the coronal hole or flare that was expected to disrupt propagation did not affect the earth.
Geomagnetic indices did rise last Friday, the day before the contest, but even then the planetary K index rose only briefly to 4. On Saturday and Sunday the planetary K index was mostly 1 or 2, and during one period was even 0. What is really interesting is that the College K index, measured in Alaska where the geomagnetic activity is higher due to proximity to the polar region, was actually 0 over six 3 hour periods on Saturday and Sunday.
Solar flux and sunspot numbers were higher this week than last, with average sunspot numbers up 54 points and average solar flux rising several points. Solar flux actually peaked for the short term during the previous week on March 22, when the noon reading at Penticton was 233.8 and the reading two hours later was 235.6. The low for week was Tuesday, when solar flux was 200.9. It may go lower this weekend, if solar flux this Sunday goes below 200.
The predicted solar flux for the next five days, Friday through Tuesday, is 205, 200, 195, 205 and 210. Flux values may again dip below 200 around April 10-16, then peak near 250 around April 22 or 23. Possible days of geomagnetic upset, based on the solar rotation are April 18 and 19 and April 28.
MSNBC ran another story this week on the so-called solar heartbeat. You can see the article at http://www.msnbc.com/news/389042.asp, which explains a theory concerning how layers of gas rotating at different speeds may affect the formation of sunspots and solar flares. MSNBC also ran a story about a new solar satellite that was launched last Saturday. Called IMAGE, or Imager for Magnetosphere-to-Aural Global Exploration, it will be used to study the relationship between solar wind and the earth's magnetosphere. It will deploy four wire antennas that are each 820 feet long, making it the longest artificial object in space. Read about it at http://www.msnbc.com/news/386647.asp?0a=235A162. NASA also ran a story on the IMAGE at http://science.msfc.nasa.gov/headlines/y2000/ast27mar_1m.htm.
Sunspot numbers for March 23 through 29 were 236, 230, 243, 255, 227, 232 and 238 with a mean of 237.3. 10.7 cm flux was 224.1, 218.9, 205.1, 211.3, 204.9, 200.9 and 208.8, with a mean of 210.6, and estimated planetary A indices were 11, 10, 8, 5, 5, 5 and 9, with a mean of 7.6.
The author joined in on the 10 and 12 meter mobile fun this week, and here are some path projections based just on those bands.
The first group of path projections is from Southern California.
The second group is from Dallas, Texas.
The third group is from Atlanta, Georgia.