GPS Derived TEC Maps

The hourly TEC maps present vertical TEC data (in TEC units, 1 TECU = 1016 el / m2) covering Europe in the ranges:

geogr. latitude:   32.5 up to 70.0 deg North
geogr. longitude: -20.0 up to 40.0 deg East

For each day, these maps are grouped in two GIF files (each containing 12 hourly plots) named YYMMDD_1.gif and YYMMDD_2.gif (YY=year, MM=month, DD=day, i.e. 970101_1.gif). The scales included represent the vertical TEC in TEC units and the corresponding range error (m) for the L1 frequency at 10 and 30 degrees elevation. Please be aware that the color scale in the GIF files differs slightly from that in the previously available postscript files.

To get the latest vertical TEC maps over Europe follow the link :

To get the hourly maps of vertical TEC over Europe follow the links to our server:

January February March April May June
July August September October November December

To get the latest vertical TEC maps over North Pole follow the link :

WARNING: The extension of the TEC maps is rather large compared with the distribution of the GPS stations we are using. That means that there are areas where we do not have any or only a few GPS data points. Due to the hybrid method applied here for deriving grid point values of vertical TEC (see introduction) at those areas adjusted model values (NTCM2) dominate. Users of the maps should therefore be careful when interpreting features in those areas with few or no GPS coverage.
We would very much appreciate hearing from people working with our TEC maps. This could be very helpful for us in improving our methods. Additionally we can provide useful information for data interpretation.

The TEC maps presented here are derived from GPS data mainly obtained at GPS ground stations of the global network of the International GPS Service (IGS). DLR staff is grateful to the IGS community for making available these high-quality ground base GPS tracking data.

Questions and comments are welcome!
Just mail to

Despite on best efforts, we cannot guarantee that these products will be provided regularly or that they are free of error. Thus we cannot assume any legal liability or responsibility for the accuracy or regularity of any information or product.