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ARRL Propagation Bulletin ARLP008 (2002)

ARLP008 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 8  ARLP008
From Tad Cook, K7VVV
Seattle, WA  February 22, 2002
To all radio amateurs 

ARLP008 Propagation de K7VVV

Average daily sunspot numbers and solar flux were both down this
week. Fortunately, geomagnetic indices were low as well. The average
daily planetary A index dropped from 10 to 6. This contrasts with
last week's warning of possible geomagnetic activity for the
weekend, although the bulletin did hedge a bit, stating effects
could miss earth and conditions turn out mild, which they did. The
result was very good conditions for the contest weekend.

Last week's bulletin suggested a rising solar flux toward the
240-245 level around February 24-28, but the latest projection shows
flux values around 200 for the next few days, gradually declining
toward 180 around March 6. There isn't much visible sunspot
activity, and holographic images show nothing substantial on the
sun's far side.

Geomagnetic conditions could become unstable by Saturday with a
planetary A index around 20. This is because of a coronal mass
ejection that left the sun on February 20, erupting from sunspot
9825. This area is right at the northwestern edge of the visible
solar disk, so any effect on earth is uncertain.

Check out this interesting set of links from the Solar Physics
Department at the Royal Observatory of Belgium. The URL is , and the department's home
page is .

Sunspot numbers for February 14 through 20 were 209, 156, 134, 121,
103, 130 and 157 with a mean of 144.3. 10.7 cm flux was 196.1, 195,
193.5, 196.6, 192.8, 189.4 and 193.4, with a mean of 193.8, and
estimated planetary A indices were 4, 4, 5, 8, 9, 4 and 8 with a
mean of 6.


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