Total electron content (TEC) is an important descriptive quantity for the ionosphere of the Earth. TEC is the total number of electrons integrated between two points, along a tube of one meter squared cross section, i.e., the electron columnar number density. It is often reported in multiples of the so-called TEC unit, defined as TECU=1016el/m2≈1.66×10−8 mol⋅m−2.[1]
TEC is significant in determining the scintillation and group and phase delays of a radio wave through a medium. Ionospheric TEC is characterized by observing carrier phase delays of received radio signals transmitted from satellites located above the ionosphere, often using Global Positioning System satellites. TEC is strongly affected by solar activity.
- ^ B. Hofmann-Wellenhof; H. Lichtenegger & J. Collins (2001). Global Positioning System: Theory and Practice. New York: Springer-Verlag. ISBN 978-3-211-83534-0.