ARRL

ARRL Propagation Bulletin ARLP019 (2000)

SB PROP @ ARL $ARLP019
ARLP019 Propagation de K7VVV

ZCZC AP19
QST de W1AW  
Propagation Forecast Bulletin 19  ARLP019
From Tad Cook, K7VVV
Seattle, WA  May 12, 2000
To all radio amateurs 

SB PROP ARL ARLP019
ARLP019 Propagation de K7VVV

Solar flux and sunspot numbers were sharply lower over the past ten
days, but are now heading higher. Solar flux reached a low on
Saturday, May 6, when the three readings for the day were 126.3,
126.8 and 126.7. The noon 126.8 reading is the official flux for the
day. Daily solar flux values have not been this low since October 2,
1999, when it was 126.3. Average solar flux for the past week was
off by over 30 points when compared to the previous week, and
average sunspot numbers were down by nearly 13.

Another interesting number to look at is the total sunspot area
visible on the solar disk. These numbers are expressed as millionths
of a hemisphere, and you can see the daily value along with the
solar flux and sunspot numbers online at
gopher://sec.noaa.gov/00/indices/DSD. We reached a low of 130 for
visible sunspot area on May 7. Sunspot area has not been this low
since September 30 and October 1, 1999. This value represents a
nearly spotless sun, and is actually equivalent to .013 percent of
the visible surface. Contrast this with a short time back, April 23,
when the sunspot area number was 2860, representing 22 times the
visible area of the May 7 value.

All of this does not mean that we have passed the peak of the solar
cycle, however. Activity jumps around quite a bit, even during a
peak year of the cycle such as this one. It is only later when
viewing smoothed numbers on a graph that the progress of a cycle
looks steady. For more information, read Solar Ups and Downs at
http://science.nasa.gov/headlines/y2000/ast09may_1m.htm.

As this bulletin is written on Thursday evening, the solar flux
seems to be ramping upward. It is measured three times per day in
Penticton, British Columbia at 1700, 2000 and 2300z, and the last
four values measured, from 2300z Wednesday through 2300z Thursday
are 167.7, 177.7, 177.7 and 186.5. The predicted solar flux for the
next five days, Friday through Tuesday, are 190, 195, 200, 200, and
205. Solar flux is expected to peak for the short term around 220 on
May 18, then drop down around 130 from June 1-3.

Unfortunately, this weekend there may be effects from a coronal mass
ejection that occurred on May 8. Predicted planetary A index for
Friday through Tuesday is 20, 20, 15, 8, 8 and 8.

Sunspot numbers for May 4 through 10 were 105, 122, 111, 130, 131,
149 and 174 with a mean of 131.7. 10.7 cm flux was 134.5, 129.8,
126.8, 130.9, 137, 149.5 and 179.2, with a mean of 141.1, and
estimated planetary A indices were 8, 14, 12, 7, 6, 11 and 7, with a
mean of 9.3.

Path projections for this week are from Chicago, Illinois and are
all to DX locations from this week's ARRL DX Bulletin ARLD020.

To Guinea, 80 meters 0030-0630z, 40 meters 0000-0700z, 30 meters
2300-0730z, 20 meters 2200-0830z, 17 meters 2100-0400z, 15 meters
possibly 2100-0200z.

To Easter Island, 80 and 40 meters 0130-1100z, 30 meters 0030-
1200z, 20 meters 0000-1300z, 17 meters 2330-1030z, 15 meters
1330-1500z and 2230-0600z, 12 meters possibly 1430-1600z or
2100-0430z.

To Ethiopia, 80 meters 0100-0300z, 40 meters 0030-0300z, 30 meters
2330-0330z, 20 and 17 meters 2300-0400z, 15 meters possibly
2200-0100z.

To Tajikistan, 20 meters 0000-0130z, 17 meters 2200-0330z, 15 meters
0000-0200z.

To Wallis and Futuna Islands, 80 meters 0530-1100z, 40 meters
0500-1130z, 30 meters 0430-1200z, 20 meters 0400-1300z, 17 meters
0300-1400z, 15 meters 0130-0900z and 1100-1700z, 12 meters
0030-0630z.

To Mongolia, 17 meters 1100-1400z.

To Midway Island, 80 meters 0630-1100z, 40 meters 0600-1130z, 30
meters 0530-1230z, 20 meters 0400-1400z, 17 meters 0300-0700z and
1200-1500z.

To Fernando de Noronha, 80 meters 0030-0800z, 40 meters 2330-0900z,
30 meters 2230-0900z, 20 meters 2130-1000z, 17 meters 2130-1000z, 15
meters 1930-0600z and 0830-1200z, 12 meters 1630-2130z and
0030-0300z.
NNNN
/EX