ARRL

ARRL Propagation Bulletin ARLP013 (2000)

SB PROP @ ARL $ARLP013
ARLP013 Propagation de K7VVV

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.

To Cleveland, Ohio, 12 meters 1330-0430z, 10 meters 1430-0230z (both
bands stronger later in the day), to Atlanta, Georgia, 12 meters
1330-0430z, 10 meters 1430-0300z, to the Caribbean, 12 meters
1400-0300z, 10 meters 1430-0130z, to Japan, 10 meters 2030-0630z, 12
meters 2100-0630z.

The second group is from Dallas, Texas.

To Seattle, Washington, 12 meters 1500-0400z, 10 meters 1630-0130z,
to Europe, 12 meters 1330-2330z, 10 meters 1530-2200z, to the
Caribbean, 12 meters 1200-0400z, 10 meters 1230-0230z, to Japan 12
meters 2000-0500z, 10 meters 2030-0330z.

The third group is from Atlanta, Georgia.

To Seattle, Washington, 12 meters 1400-0400z, 10 meters 1500- 0300z,
to Europe, 12 meters 1300-2300z, 10 meters 1530-2200z, to Brazil, 12
meters 1130-0400z, 10 meters 1230-0200z.
NNNN
/EX