ARRL

ARRL Propagation Bulletin ARLP016 (2000)

SB PROP @ ARL $ARLP016
ARLP016 Propagation de K7VVV

ZCZC AP16
QST de W1AW  
Propagation Forecast Bulletin 16  ARLP016
From Tad Cook, K7VVV
Seattle, WA  April 24, 2000
To all radio amateurs 

SB PROP ARL ARLP016
ARLP016 Propagation de K7VVV

Sunspot numbers were up slightly this week, and average solar flux
was down when compared to last week. Solar flux probably reached a
short term low around Sunday or Monday, when the thrice daily
readings for the two days were 157.9, 159, 156.7, 158.1, 157.9 and
157.1. Solar flux readings are taken daily at 1700, 2000 and 2300z
at Penticton, but it is the 2000z reading that is the official solar
flux value for the day. Sunday was the most disturbed day in terms
of geomagnetic indices, when the planetary A index was 23 and the K
index went as high as 5.

Solar flux should rise over the next few days, going above 200
around April 24 and peaking near 220 around April 28 or 29. This
should improve 10 and 12 meters, although the seasonal effects as we
move toward late spring and summer will mean that the highest HF
bands are not as interesting as they were at the equinox.

The forecast for the next five days, Friday through Tuesday, shows
solar flux values of 185. 190, 195, 200 and 210. Predicted planetary
A index for those same days is 12, 5, 5, 5, and 8.  Geomagnetic
conditions should stay fairly quiet, but April 29 could have
unsettled to active geomagnetic conditions.

An AP wire service story this week talked about research reported in
the May 1 issue of Geophysical Research Letters which uses data from
the SOHO satellite to determine when solar activity on the other
side of the sun may rotate into view. An increase in L-Alpha
radiation accompanies sunspots, and it brightens hydrogen atoms in
space. The SOHO satellite can detect these hydrogen atoms that are
illuminated by sunspots from areas of the sun not currently facing
earth, and researchers can predict when these active areas will
rotate into view.

Sunspot numbers for April 13 through 19 were 190, 173, 177, 170,
166, 167 and 179 with a mean of 174.6. 10.7 cm flux was 164, 165.2,
163.7, 159, 157.9, 160.4 and 167.7, with a mean of 162.6, and
estimated planetary A indices were 8, 5, 7, 23, 14, 7 and 12, with a
mean of 10.9.

Path projections for this weekend are from Miami, Florida.

To Europe, 80 meters 2330-0530z (best 0230-0400z), 40 meters
2300-0630z (best 0030-0430z), 30 meters 2200-0800z (best
0000-0430z), 20 meters 2100-0700z and 0830-1000z, 17 meters
2000-0230z and 0830-1030z, 15 meters 1000-1530z and 1800-0130z, 12
meters 1230-2300z, 10 meters 1530-2030z.

To Southern Africa, 80 meters 2330-0430z, 40 meters 2300-0500z, 30
meters 2200-0530z, 20 meters 2130-0630z, 17 meters 2100-0230z and
0500-0630z, 15 meters 2100-0130z, 12 meters 2000-0100z, 10 meters
2000-0000z.

To South America, 80 meters 2330-1000z, 40 meters 2300-1030z, 30
meters 2200-1100z, 20 meters open all hours, best 0030-0930z,
weakest 1430-1900z, 17 meters open all hours, best 2330- 0730z,
weakest 1530-1800z, 15 meters 1030-0630z, best 2330-0600z, 12 meters
1130-0530z, 10 meters 1230-0500z.

To the Caribbean, 80 meters 2200-1130z, 40 and 30 meters open all
hours, best 0030-0930z, 20 meters open all hours, weakest
0630-0900z, 17 meters 1200-0400z, 15 meters 1330-2200z, 12 meters
possibly 1530-2030z.

To Australia, 80 meters 0830-1130z, 40 meters 0800-1200z, 30, 20 and
17 meters 0700-1230z, 15 meters 0600-0800z, 12 meters 0530-0700z, 10
meters 0500-0630z.

To Japan, 80 meters 0930-1030z, 40 meters 0930-1100z, 30 meters
0830-1130z, 20 meters 0800-1230z, 17 meters 0600-0700z and
1030-1300z, 15 meters 1200-1330z and 0400-0530z, 12 meters possibly
2030-0200z.
NNNN
/EX