ARRL

ARRL Propagation Bulletin ARLP031 (2002)

SB PROP @ ARL $ARLP031
ARLP031 Propagation de K7VVV

ZCZC AP31
QST de W1AW  
Propagation Forecast Bulletin 31  ARLP031
From Tad Cook, K7VVV
Seattle, WA  July 26, 2002
To all radio amateurs 

SB PROP ARL ARLP031
ARLP031 Propagation de K7VVV

Active sunspot regions have been coming into view, with a resulting
rise in solar flux and sunspot numbers.  Average daily sunspot
numbers were up nearly 30 points, and solar flux up about the same
amount when compared to the previous week.  Wednesday had a very
high sunspot number of 270, the highest since May 4th and 5th, when
it reached 271 and 317.

On July 23 sunspot 39 emitted a strong flare, but didn't cause any
major upset.  Planetary K indices on Thursday are running between
two and three.  But earlier in the week the geomagnetic field was
quite unsettled, with planetary K indices of four from July 20-23.
On July 22 the planetary K index reached five, and Alaska's high
latitude college K index went to six.

Sunspot numbers are expected to remain fairly high, continuing above
200 over the next few days.  As long as there aren't any geomagnetic
storms, this is good for HF propagation.  The current outlook for
Friday through Monday is solar flux at 220, 220, 225 and 225, and a
mild geomagnetic outlook with predicted planetary A index values of
15, 10, 10 and 8.

Last week's bulletin mentioned a source for historical sunspot data
at ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/.  NG3K
wrote to say that when he saw the bulletin, the link was missing the
underline characters between SOLAR and DATA and between SUNSPOT and
NUMBERS.  Without these, the link was bad.  Apparently the bulletin
was sent over some mediums this way.  With luck it won't happen with
the same link as it is repeated above.  NG3K has a nice web site
devoted to DX and contesting at www.ng3k.com.

Sunspot numbers for July 18 through 24 were 166, 148, 136, 131, 176,
226 and 270, with a mean of 179. 10.7 cm flux was 180.7, 182.3,
184.8, 182.8, 189.7, 198.3, and 208.4, with a mean of 189.6.
Estimated planetary A indices were 8, 12, 18, 19, 20, 18, and 12,
with a mean of 15.3.
NNNN 
/EX