Global maps of the total electron content and conditions of radio wave propagation in the ionosphere

In the 20th century, the main parameter to specify the propagation conditions was the critical frequency foF2, measured by the ionosondes providing high accuracy, but having quite a rare observation network. In the 21st century, it became possible to use these navigation satellites that provide continuous global monitoring of such a parameter as the total electron content TEC of the ionosphere. On example of estimation of radio wave characteristics near the path Cyprus-Moscow it is shown that joint using global maps of TEC and data of vertical sounding can be useful to: 1) choose the map most coincident with experimental values of the critical frequency foF2, 2) fill in gaps of foF2 and maximum useable frequencies, Such using allows to investigate and more correctly predict conditions of ionospheric propagation of radio waves.