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ARRL Propagation Bulletin ARLP005 (2001)

ARLP005 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7VVV
Seattle, WA  February 2, 2001
To all radio amateurs 

ARLP005 Propagation de K7VVV

Thanks to K9LA for writing last week's bulletin in my absence.

This week we will catch up on the solar and geomagnetic data for the
past couple of weeks.  Users of Scott Craig's solar data plotting
software, which automatically sucks the data from this bulletin and
displays it, will want to go to his website at to download the latest version.

Since there are two weeks of data in this bulletin, users of the
plotting utility will want to edit the bulletin into two versions
with only one week's data each, so that the software can
automatically grab the data.  Version 3.09 released on January 9
made it compatible with Windows 2000, and version 3.10 released
yesterday added a minor feature to remember the last directory where
the propagation bulletins are stored.

Solar flux and sunspot numbers dipped from our last reporting period
(January 11-17) to the next (January 18-24) and then rose again over
the last week.  Geomagnetic conditions have been pretty stable, but
over three dates recently (January 21, 24 and 31) planetary A
indices were 18 and planetary K indices were briefly at 5.

Geomagnetic conditions are expected to remain stable, and solar flux
should rise over the next few days.  Solar flux for Friday through
Tuesday is predicted to be 165, 165, 170, 175 and 175.  Monday and
Tuesday's values are the expected peak for the short term, and the
next peak is predicted around March 7.  Probably the best daytime DX
band currently is 15 meters, but it should do well into the evening
to the south and west.

Average daily solar flux for November, December and January was
178.8, 173.6 and 166.6.  Average daily sunspot numbers for the same
three months was 149.9, 146.4 and 142.7.  This indicates the gradual
decline of cycle 23, but of course these values are not far below
the peak of the cycle, which probably occurred last summer.

Sunspot numbers for January 18 through 24 were 99, 134, 91, 108,
108, 178 and 186 with a mean of 129.1. 10.7 cm flux was 151.5,
152.5, 153.2, 151.5, 162.1, 167.1 and 172.5, with a mean of 158.6,
and estimated planetary A indices were 4, 4, 8, 18, 10, 11 and 18
with a mean of 10.4.

Sunspot numbers for January 25 through 31 were 163, 157, 134, 124,
142, 128 and 130 with a mean of 139.7. 10.7 cm flux was 168.6,
165.6, 166.8, 167.6, 165.4, 159.6 and 153.3, with a mean of 163.8,
and estimated planetary A indices were 4, 10, 4, 6, 13, 4 and 18
with a mean of 8.4.


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