Topband: 160 Meter Propagation

[Thomas F. Giella KN4LF]

Carl K9LA is correct in his assertion that change in height of the 
ionosphere in the equatorial region during solar minimum does not translate 
to a change in the height of the mid and high latitude ionosphere. However 
at and near solar minimum the mid and high latitude D layer of the 
ionosphere at mesosphere altitude cools approximately 2 degrees C, contracts 
in thickness and signal absorption in the layer increases.

Also a solar flux in the mid 100's is necessary for routine stable formation 
of the E Valley/F Layer ducting mechanism. Therefore formation of the duct 
is less prevalent at the bottom of solar cycle and long haul propagation 
poorer at solar minimum.

73 & GUD DX,
Thomas F. Giella, KN4LF
Lakeland, FL, USA
kn4lf at arrl.net

KN4LF Daily Solar Space Weather & Geomagnetic Data Archive: 
http://www.kn4lf.com/kn4lf5.htm