Friends in Radio Land-
I have been reading the mail, all the complaints about poor propagation
during the recent contest. For what they're worth, I just wanted to put
in a few words for you to think about.
First, the K- and A-indices that are important in the scheme of things are
taken from data recorded by high latitude magnetometers - College, AK,
Meanook, AB; Ottawa, ON; Abisko, Sweden, etc. They give a measure of the
energy input to the auroral zone; you can get the same thing from the
NOAA auroral satellite data. Anyway, that energy shows up as heat in the
atmosphere and can be conveyed or conducted equatorward to affect the
atmosphere. But those indices are primarilhy important when it comes to
trans-auroral propagation as they give a measure of absorption/skewing
that signals may experience.
Myself, I am quite convinced there is an atmospheric or weather factor
that affects low-band propagation across the middle latitudes. There are
good reasons to believe that and I discuss some of them in a QEX article
that will come out next spring. The main theoretical idea involved has to
do with the high collision rate between ionization and the surrounding
neutral atmospheric constituents; thus, whatever atmospheric motions there
are in the upper atmosphere are conveyed to the ionization we depend on.
But to explore that further, we need more atmospheric measurements at high
altitude or a more careful look at weather maps. In the absence of NOAA
or NASA launching a high-altitude wind study, we have to work with
low-altitude weather maps and see if any connection can be made between
what is seen there and top-band propagation.
I should add that there is a magneto-ionic factor and I am reminded of
that as sitting here with the 9G5AA logs in hand, I can see it must be a
joy to operate from a low-magnetic latitude, relying on what is called
quasi-longitudinal propagation (with an exotic call sign). I think it
beats quasi-transverse propagation across the USA, looking for New
England.
In summary, I wasn't on the band for the contest but I sympathize. I
think there is more to learn but it is not with the magnetic indices; we
need high-altitude atmospheric data where the 1.8 MHz RF travels or at
least a cheap substitute.
73,
Bob, NM7M
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