Back to: TEC Regional Map (comparison page)

This map shows the total electron content (TEC) as measured by GPS recievers. The ionosphere is modelled as a thin shell at 400km in altitude and the point where the satellite-receiver line of sight passes through this shell is known as the ionospheric peirce point (IPP). The TEC shown is averaged using all IPPs within each grid cell. Typically there are several hundred IPPs available at any given time with the GPS receiver network in use.

For details of how the GPS data is turned into the smooth TEC map shown here see About TEC Mapping.