Friends in Radio Land -
The Fall DX season is about to begin and I thought I would give
some idea of good days, as suggested by data from the Meanook
magnetometer in Canada. But, alas, the news is grim for any
predictions 27 days in advance.
Where I normally look for low K-sums during a 15-day reporting
period, say K-sums well below 10, the reporting period from August
16 to 31 had a low K-sum of 13 and a high K-sum of 49. There was
not a quiet time to be found. Indeed, looking at 120 different
3-hour reporting periods, 30 of the them had K-values of 5 or
greater: 13 for K=5, 11 for K=6 and 6 for K=7. The "good news"
was there were no horrendous magnetic storms, with Ks of 8 or 9.
Statistically, the period around the equinoxes is not the best as
magnetic storminess goes through a statistical peak then, as shown
by the following distribution:
Magnetic storms per month
1,475 storms from 1868 to 1992
Number
180
*
160 * * *
* * * *
140 * * * *
* * * * *
120 * * * * * * * *
* * * * * * * *
100 * * * * * * * * *
* * * * * * * * *
80 * * * * * * * * * * * *
* * * * * * * * * * * *
60 * * * * * * * * * * * *
* * * * * * * * * * * *
40 * * * * * * * * * * * *
* * * * * * * * * * * *
20 * * * * * * * * * * * *
* * * * * * * * * * * *
J F M A M J J A S O N D
Data from the National Geophysical Data Center, Boulder, CO.
The equinoxes are times when the magnetosphere is looking straight
into the solar wind and the energy transfer from the solar wind to
the magnetosphere is most efficient then. That being the case, it
would look like days of magnetic quiet may be relatively rare in
the near future; but they DO occur so one will just have to stay
on top of the A-and K-indices to find the most promising operating
times and take advantage of them.
But those remarks are for paths going to high latitudes;
transequatorial paths are less subject to those problems as the
geomagnetic field lines at lower latitudes do not go out as far
toward to the front of the magnetosphere. That being the case,
paths from the Northern Hemisphere to Oceania, Africa and South
America should perform quite well, everything considered.
73,
Bob, NM7M
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