Examples of meteorological behavior of the ionosphere

For some time the network of ionosonde stations in Europe were dense enough to study the meteorological behavior of the ionosphere. Because the electron recombination near the maximum of the F-region ionization is sufficiently small, the maximum electron density and the profile are controlled substantially by dynamic processes. Gravity waves and vertical plasma drift and its vertical gradients change the F-layer ionization significantly. In fixed frequency ionosonde recordings the author has discovered direct oblique echoes from a hole in the ionosphere over the Alps. Maps were drawn to show the meteorological properties of this European Anomaly either as a time development of a cross-section of Europe from northern Germany to Rome, Italy using six stations, or as a sequence of a contour maps of the ionosphere over Europe using ten stations. A short animated movie was produced demonstrating the development of the hole in the ionosphere and its recovery with a curl developing. Even the average behavior of the F-region ionization shows substantial differences with location. In Europe the variations of the local gradients in ionization can be different by a factor of two over two locations separated by 1000 km. This behavior, important for understanding the meteorology of the ionosphere and for precise ionspheric radio predictions, certainly requires intense studies with digital sounders in Europe and at other locations.