hello to everyone,
With respect to Wolf DF2PY's comment about very good propagation on polar
routes when the A index and the solar wind speed are elevated, our
understanding of what makes 160m tick is lacking. In other words, "stuff
happens".
Having said that, there have been similar reports of good propagation on
160m at high latitudes when the K index spikes up. A process that could
explain this is tied to changes in the E region and lower F region at
elevated K indices. When geomagnetic field activity increases, the
atmosphere's electric field (measured in terms of mV/meter) increases. When
this happens, the electron density valley above the E region peak can
become better developed (deeper and more vertical extent - which would
eliminate transits through the absorbing region and eliminate ground
reflections).
This process comes from a 1984 paper in the Journal of Geophysical
Research. It is only a model - I'm not aware of any measurements to confirm
that this happens. So "buyer beware". All I can say is - it makes sense.
Carl K9LA
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|