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ARRL Propagation Bulletin ARLP029 (2001)

ARLP029 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 29  ARLP029
From Tad Cook, K7VVV
Seattle, WA  July 13, 2001
To all radio amateurs 

ARLP029 Propagation de K7VVV

Solar flux and sunspot numbers declined again this week. Average
sunspot numbers were down by nearly 21 points and average solar flux
was off by over 10 points. There were no big geomagnetic upsets this

The most active day was Sunday, when the planetary A index was 16,
and the K index went to 4 toward the end of the UTC day. There were
reports of interesting VHF Sporadic E skip on Sunday. AJ4JF in
Knoxville, Tennessee was tuning the FM broadcast band in his car and
around mid-day heard eight stations in Texas, one from New Mexico,
three from Colorado and one from Kansas. Many of them were very
clear and full-quieting.

WA5IYX wrote that he runs a web site that takes reports such as this
at and for 2-meter hams offers

June 30 was the end of another quarter, so here are some quarterly
averages of the sunspot and solar flux numbers reported in this
bulletin. This starts with the first quarter of 1999 and ends with
the second quarter of 2001. Average daily sunspot numbers were 96.1,
147.2, 137.9, 163.1, 168.9, 190.8, 187.4, 145, 147.3 and 164.8.
Average daily solar flux was 136.7, 145, 157.6, 175.2, 180.5, 182.9,
181.9, 173.3, 164.4 and 166.7. It appears that sunspot numbers
peaked in the second quarter of 2000, and solar flux had a broader
peak throughout the first nine months of last year. Both indices got
a boost in the second quarter of this year.

The latest forecasts look fairly good for the IARU HF World
Championship this weekend. There was an eruption on the sun on
Thursday morning, but it was aimed away from earth, and the
geomagnetic outlook for the next week looks stable. Solar flux
forecast for the next few days, Friday through Monday, is 135, 140,
140 and 145. Recent forecasts had flux values peaking near 200, but
there are no substantial new sunspots visible via helioseismic
holography on the sun's far side. Current forecasts place the short
term peak near 170 around July 20-22.

Sunspot numbers for July 5 through 11 were 101, 68, 77, 101, 109,
116 and 115 with a mean of 98.1. 10.7 cm flux was 119.6, 116.4,
117.8, 126.3, 130, 130 and 131.9, with a mean of 124.6, and
estimated planetary A indices were 13, 10, 7, 16, 11, 11 and 9 with
a mean of 11.


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