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ARRL Propagation Bulletin ARLP033 (2002)

ARLP033 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 33  ARLP033
From Tad Cook, K7VVV
Seattle, WA  August 9, 2002
To all radio amateurs 

ARLP033 Propagation de K7VVV

After the previous week's heightened activity solar flux and sunspot
values rolled back quite a bit. Average daily sunspot numbers for
this week were down 120 points and average daily solar flux was off
nearly 70 points. Solar flux values fell since reaching 241.5 on
July 16 but should rise again next week. Solar flux values predicted
for August 10-16 are 135, 140, 145, 145, 150, 150 and 160.
Currently solar flux is expected to peak around August 23-24 near
215 based on the previous solar rotation.

Geomagnetic conditions should be quiet for the next few days, but it
sure wasn't quiet August 1-3 when planetary K indices reached 6,
indicating a geomagnetic storm complete with dramatic aurora
displays at northern latitudes. Check out this link at from the Auroral Station at Adventdalen in
Norway. Also check these links from the University of Alaska for
more aurora information: Don't forget to
check and for daily space weather updates.

Day by day we will gradually move away from summertime to fall
propagation. We will especially notice a change on 10, 12 and 15
meters, which are affected by thinning of the ionosphere during the
summer. K3MIY mentioned in an email this week that ionospheric
heating in the northern hemisphere causes this. Presently the most
reliable DX band is 20 meters.

K9GY asked for a plug for the CW portion of the Worked All Europe DX
Contest this weekend. He mentioned for more info
on the contest. For path projections, those interested in working
Europe might use a solar flux value around 140 plugged into the
W6ELprop software, which you can download from W6EL recently updated the software to
version 2.61, making some improvements to the user interface.

Sunspot numbers for August 1 through 7 were 259, 220, 218, 150, 144,
135 and 141, with a mean of 181. 10.7 cm flux was 192.6, 180.3,
167.8, 150.9, 141.9, 144.6, and 136.2, with a mean of 159.2.
Estimated planetary A indices were 26, 37, 20, 16, 8, 9, and 8, with
a mean of 17.7.


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