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Currently the SWACI services are migrated to the Ionosphere Monitoring and Prediction Center (IMPC). This may cause downtimes of several products or parts of this webpage. To get latest news and product updates please visit impc.dlr.de!

TEC Maps

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The total electron content (TEC) is defined as the integral of the electron density along the ray path between satellite and receiver. Thus, TEC provides the number of electrons per square meter. The most frequently used unit is 1TECU = 1x1016 electrons / m2.


TEC is derived from dual frequency code and carrier phase measurements provided by Global Navigation Satellite Systems (GNSS). SWACI uses GPS measurements from various European GNSS networks such as the International GNSS Service (IGS), European Reference Frame (EUREF), Norwegian Mapping Authority (NMA), and ascos distributed by the Federal Agency of Cartography and Geodesy (BKG) Frankfurt. The global TEC maps are mainly created by using data provided by the International GNSS Service Real-Time Pilot Project (IGS-RTPP).


To generate TEC maps of vertical TEC, the slant measurements have to be transformed to the vertical. In a first approximation the ionospheric range error in GNSS is proportional to TEC.


These TEC maps are used to derive latitudinal and zonal gradients, rate of change of TEC (5 min increments), 27 days medians, hourly forecasts of TEC, and corresponding error estimates.


Spatial resolution (latitude x longitude): 2 °x 2° (Europe), 2.5° x 5° (globally)


Latency: < 5 min




TEC global >