The term Total electron Content (TEC) implies the value of total number of electrons, which are located along a path between two points. Usually this parameter are in units of electrons per square meter, where 1016 electrons/m2 = 1 TEC unit (TECU). TEC is an important numerical parameter that describes the state of Earth’s ionosphere. The main part of electrons and ions is concentrated on the both sides of magnetic equator. This occurs because of vertical plasma drift of charged particles at middle and low latitudes.
The TEC maps (e.g. presented on this website) are of interest for many scientifical and practical applications. Global TEC maps are often used for the monitoring of current radio wave propagation conditions. Given a possibility to build a precise nowcasting of ionospheric conditions, one can come up with a short term ionospheric state forecast.