Ionospheric trough observation over Europe according to radiotomography under different geomagnetic conditions

Some examples of radiotomographic reconstructions of main ionospheric trough over Europe using navigational satellite systems (low-orbital and high-orbital) data are considered under different geomagnetic conditions. A complicated structure of the main ionization trough with its polar wall moving equatorwards was observed during the geomagnetic storms. The trough position, depth and width vary within a wide range depending on geomagnetic activity.