ARRL

ARRL Propagation Bulletin ARLP008 (2000)

SB PROP @ ARL $ARLP008
ARLP008 Propagation de K7VVV

ZCZC AP08
QST de W1AW  
Propagation Forecast Bulletin 8  ARLP008
From Tad Cook, K7VVV
Seattle, WA  February 25, 2000
To all radio amateurs 

SB PROP ARL ARLP008
ARLP008 Propagation de K7VVV

Solar flux and sunspot activity were down last week, but heading
back up.  Average solar flux for last week compared to the previous
week was down almost 4 points, and sunspot numbers were off about 28
points.  The low point was Friday, February 18, when the three solar
flux measurements for the day were 139.6, 141.1 and 140.4.  The noon
measurement of 141.1 is the official reading for the day.  Solar
flux is expected to rise, with the projection for Friday through
Tuesday of 197, 197, 200, 200 and 204.  Solar flux for the near term
is expected to peak around 205 on Wednesday or Thursday, March 1 and
2, then decline to below 170 by March 9, and bottom out near 130
around March 23 or 24.

Planetary A index has been rising, due to a well-placed coronal hole
streaming charged particles toward the earth.  NASA has an
interesting article about this as well as a dramatic photo online at
http://www.spacescience.com/headlines/y2000/ast23feb_2.htm.  Also
check http://www.spaceweather.com, which on Thursday had an article
about a gust of solar wind at 1430z on February 24.

The projected planetary A index for Friday through Tuesday is 20,
18, 15, 13 and 10.  Conditions may be disturbed again around March 4
and 5, and fairly quiet between March 13-20.  Based on the current
solar rotation, disturbed conditions may recur around March 22-23,
and possibly quiet conditions again around March 26-29, although
predictions that far in the future are more of a guess.  These
projections are based upon sunspots and coronal holes moving across
the visible solar surface, as the sun rotates relative to earth
every 27.5 days.  Various features grow and fade with time, and new
areas appear.  Some are oriented toward earth and have a large
effect, while others do not.

The coronal hole that is causing the current geomagnetic disturbance
has been visible for the last seven solar rotations.

Doug Brandon, N6RT wrote to ask about the URL for Cary Oler's Solar
Terrestrial Dispatch web site, which seemed to disappear some time
back.  Doug did some detective work, and found that it had moved.
The new site is at http://solar.spacew.com/.

George Jacobs, W3ASK has an interesting item in his propagation
column in the March issue of CQ Magazine concerning equinoctial
propagation.  This is about the effect that occurs in spring and
fall seasons when the daylight distributed between the northern and
southern hemisphere is roughly equal, dependent on how close the
date is to the equinox.  He says that during March intercontinental
openings on 160-30 meters should peak just before local sunrise and
again at local sunset.  20 meter openings should peak an hour or two
after sunrise and again for an hour or so after sunset.  17-6 meter
intercontinental openings should peak during daylight hours.
Signals on these upper bands are stronger toward the west around and
after sunset, while toward the east they are stronger before noon.
He notes that signals to the south are stronger after sunrise and
again late in the afternoon.  W3ASK has a web site at
http://www.gjainc.com/.

Sunspot numbers for February 17 through 23 were 152, 146, 126, 131,
122, 129 and 155 with a mean of 137.3.  10.7 cm flux was 168.4
141.1, 144.8, 153.3, 152.1, 172.3 and 185.1, with a mean of 159.6,
and estimated planetary A indices were 6, 2, 4, 5, 15, 5 and 9, with
a mean of 6.6.

Path projections this week are from Boston, MA, and are based on
Sunday, February 27 with a solar flux of 200.

To Western Europe, 80 meters 2200-0800z, peaking 2300-0000z and
again at 0630z, 40 meters 2030-0900z, 30 meters 1830-1100z, 20
meters 1030-0400z, 17 meters 1130-2230z, 15 meters 1230-2130z, 12
meters 1330-2030z, 10 meters 1430-1930z.

To Eastern Europe, 80 meters 2130-0530z, 40 meters 2130-0630z, 30
meters 2030-0730z, 20 meters 1730-0630z, 17 meters 1100-2300z, 15
meters 1200-2030z, 12 meters 1230-1930z, 10 meters 1300-1830z.

To Southern Africa, 80 meters 2200-0430z, 40 meters 2200-0500z, 30
meters 2100-0500z, 20 meters 2030-0600z, 17 meters 2000-0030z, 15
meters 2000-0000z, 12 meters 1830-2230z, 10 meters 1900-2130z.

To South America, 80 meters 2300-0930z, 40 meters 2300-1000z, 30
meters 2200-1030z, 20 meters 2200-1100z, 17 meters open all hours,
strongest 2300-0500z, weakest 1300-2000z, 15 meters 1100-1300z and
1930-0300z, 12 meters 1200-0030z, 10 meters 1200-0000z.

To the Caribbean, 80 meters 2200-1100z, best 0100-1000z, 40 meters
2030-1300z, best 2330-1000z, 30 meters open all hours, best
2330-1000z, weakest 1530-1800z, 20 meters open all hours, best
2300-1030z, weakest 1500-1830z, 17 meters 1130-0130z, 15 meters
1200-0030z, 12 meters 1230-2300z, 10 meters 1300-2200z.

To Australia, 80 meters 0930-1130z, 40  30 meters 0900-1300z, 20
meters 1200-1330z and 0800-0830z, 17 meters 1330-1530z, 15 meters
1400-1600z, 12 meters 1500-1530z.

To Japan, 80 meters 0830-1200z, 40 meters 0800-1230z, 30 meters
0700-1330z, 20 meters 0600-1430z and 2130-2230z, 17 meters
2000-0000z, 0530-0830z and 1300-1600z, 15 meters 2100-0200z, 12
meters 2130-0030z, 10 meters 2200-2230z.
NNNN
/EX