ARRL

ARRL Propagation Bulletin ARLP002 (2000)

SB PROP @ ARL $ARLP002
ARLP002 Propagation de K7VVV

ZCZC AP02
QST de W1AW  
Propagation Forecast Bulletin 2  ARLP002
From Tad Cook, K7VVV
Seattle, WA  January 14, 2000
To all radio amateurs 

SB PROP ARL ARLP002
ARLP002 Propagation de K7VVV

Sunspot activity and solar flux were up over the past week.  Average
solar flux rose over 30 points to 163.8 and average daily sunspot
number was up over 50 points to 136.6 compared to the previous week.

Geomagnetic conditions were quieter over the past week.  This is
important for good HF propagation, because higher geomagnetic
activity (reflected in the daily A index and the K index measured
every three hours) results in higher absorption of HF radio waves.

The most recent active period was from December 31 to January 6,
when the planetary A index was as high as 27 on New Year's Eve day
and on New Year's Day.  When solar activity such as flares or
coronal holes bombard the earth with protons, polar regions
experience the greatest effect.  As a result, daily A indices taken
in Alaska on December 31 and January 1 were 40 and 44, with K
indices as high as six.

When the solar surface relative to earth rotates this same active
region toward us about 27.5 days after the recent activity, we could
see similar effects around January 26 until February 3.  A recent
forecast shows the planetary A index rising to 25 on January 27 and
28, then drifting down gradually to unsettled conditions with an A
index of 10 on January 31.  The next few days may see a rise in
activity, with the A index peaking again near 20 around February 2.

Solar flux has been rising this week, with a greater than 14 point
rise from Monday to Tuesday and a greater than 18 point rise on
Wednesday.  The forecast for this weekend, Friday through Sunday, is
for solar flux to rise from 205 on Friday to 210, and then 215 on
Sunday, with a wonderfully low planetary A index of 5 for all
weekend.

HF operators should be very happy with a rising solar flux combined
with low geomagnetic activity.  Beyond the weekend expect the solar
flux to remain high until around January 20, finally drifting down
to around 135 for the period from January 26 to February 1.

A group of seventh graders at Ritchie County Middle/High School in
Ellenboro, West Virginia sent an interesting note and graph.  They
kept track of the weekly average of sunspot numbers through November
and December, and at night logged AM radio stations.  Their graph
correlates the maximum skip distance with the rise and fall of
sunspot numbers.

Also arriving in this week's postal mail were some charts from NOAA
Space Environment Center showing the new Space Weather Scales, which
are numeric ratings for radio blackouts, solar radiation storms and
geomagnetic storms.  Each is rated from 1 through 5.

The worst radio blackout is an R5, and the effect is described as
''complete HF radio blackout on the entire sunlit side of the earth
lasting for a number of hours.  No HF radio contact with mariners or
en route aviators.''  It notes that there is less than one R5 event
per solar cycle.

For a G5 rated geomagnetic storm, which averages four days per solar
cycle, it says that power system grids can collapse and transformers
experience damage.  Pipeline currents can reach hundreds of amps, HF
radio propagation is impossible for one to two days, and the aurora
can be seen from the equator.  A G5 rating corresponds to a K index
rating of 9!  K indices of 9 over a 24 hour period would result in
an A index of 400, which is not a pleasant thought for HF operators.

You can see descriptions of these Space Weather Scales at
http://www.sec.noaa.gov/NOAAscales/index.html.

As a final note, check out the web-based Space Physics Textbook at
http://www.oulu.fi/~spaceweb/textbook/Welcome.html.

Sunspot numbers for January 6 through 12 were 145, 146, 106, 119,
88, 148 and 204 with a mean of 136.6.  10.7 cm flux was 144.8,
149.8, 154.7, 160.6, 163.2, 177.6 and 195.7, with a mean of 163.8,
and estimated planetary A indices were 17, 8, 6, 3, 6, 16 and 9,
with a mean of 9.3.

Our path projection for this week is from Ellenboro, West Virginia,
the home of KC8KOH, the Ritchie County Middle/High School Amateur
Radio Club.

To Europe, 80 meters 2130-0930z (best 0100-0700z), 40 meters
2000-1130z, 30 meters all hours, strongest 2230-0800z, weakest
1430-1800z, 20 meters 1130-2330z, 17 meters 1230-2130z, 15 meters
1300-2100z, 12 meters 1330-2000z, 10 meters 1400-1930z.

To Southern Africa, 80 meters 2200-0430z, 40 meters 2130-0500z, 30
meters 2100-0530z, 20 meters 1930-0030z, 17 meters 1730-1330z, 15
meters 1630-2300z, 12 meters 1230-2130z, 10 meters 1300-2100z.

To South America, 80 meters 2300-1000z, 40 meters 2300-1030z, 30
meters 2200-1100z, 20 meters 2030-0800z and 1130-1230z, 17 meters
1230-0200z, 15 meters 1200-0100z, 12 meters 1230- 0000z, 10 meters
1300-2330z.

To the Caribbean, 80 meters 2200-1200z, 40 meters all hours, best
2300-1030z weakest 1600-1800z, 30 meters open all hours, best
2300-1030z, weakest 1530-1830z, 20 meters 1130-0130z, 17 meters
1200-0030z, 15 meters 1230-2330z, 12 meters 1300- 2230z, 10 meters
1330-2200z.

To Australia, 80 meters 0930-1330z, 40 meters 0930-1400z, 30 meters
0830-1430z, 20 meters 1230-1600z, 17 meters 1400-1800z, 15 meters
1430-1830z, 12 meters 1500-1930z, 10 meters 1500-1730z.

To Japan, 80 meters 0700-1300z, 40 meters 0600-1500z, 30 meters
0530-1600z, 20 meters 2100-0230z and 0330-1900z, 17 meters
2100-0130z, 15 meters 2130-0130z, 12 meters 2200-0000z, 10 meters
2200-2300z.
NNNN
/EX