The reports of unusual propagation on November 1 are certainly
interesting. As for an explanation, we have to remember that we can
hardly predict what makes a good night and what makes a bad night on
160m. So trying to explain an event that happens very rarely is an
extremely difficult challenge. The major problem is we don't have any
good consistent measurements of what's going on in the lower ionosphere
at night. Yes, we have ionosondes, but they are quite useless at night
for 160m work since the nighttime plasma frequencies (electron
densities) at D and E region altitudes are below the sensitivity of
typical ionosondes - thus at night ionosondes only "see" the F region.
The 160m observations of K8DO and others, coupled with YO3FFF's medium
wave observations, could lead us to believe that November 1 falls into
the category of often-observed high latitude enhancements tied to a
spike in the K index. Unfortunately nothing shows up in the geomagnetic
data of the magnitude typically seen in other similar enhancements.
YO3FFF's hypothesis about the Moon acting as a shield between the Sun
and the Earth making the gyro frequency to be very low allowing MW to
propagate on higher F layer and possible ducting has two major problems.
First, the electron gyro-frequency is dependent on the strength of the
Earth's magnetic field, so how does the Moon provide a shield to the
Earth's magnetic field so that the strength would decrease? Second, the
electron gyro-frequency is the frequency at which electrons spiral about
magnetic field lines - it has nothing to do with the quantity of electrons.
Carl K9LA
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