The high-latitude ionosphere is characterized by a  strong electrodynamic coupling with the magnetosphere.
High latitude plasma convection, field aligned currents and precipitation of energetic particles are the most driving forces for very dynamic and complex processes causing a large variability of the plasma density.
In particular enhancements of the solar wind energy generate large perturbations in the high-latitude ionosphere and thermosphere that
commonly propagate towards lower latitudes.
So high latitudes are a kind of  Space "weather kitchen" for numerous perturbation phenomena observed in mid-latitudes.
The monitoring of  the total ionization of this region may improve our understanding of  complex coupling processes between the solar wind, magnetosphere, ionosphere and thermosphere.
In order to monitor the Northern high latitude ionosphere, we apply the same procedure as used for monitoring the European ionosphere.
A reliable data base is provided by about 30 GPS ground stations of  high the latitude GPS network of the International GPS Service (IGS).
The GPS data provide the total electron content (TEC) of the ionosphere along active  radio links between GPS satellites and ground receivers.
These slant TEC data are converted to vertical TEC maps over the entire Northern polar cap at latitudes  phi > 50°N with a time resolution of up to 10 minutes in our routine processing mode.
To ensure the reliability of the generated TEC maps we have developed a polar TEC model (NTCMP-1) that - working as a background model - is combined with numerous actual observations by a weighting procedure.
This assimilation technique has been successfully applied on the routine generation of TEC maps over the European area since 1995. Nevertheless, further validation work is needed, indicating that the routinely produced TEC maps have still an experimental status.
If you need assessments of the accuracy or reliability of special events, please contact us .
Although the data coverage is permanently changing, the figure illustrates a typical situation (100 measurements) by plotting the half width of the weighting functions constructed around each sub- ionospheric point.
Vertical TEC values are computed for a grid that consists of  768 grid points within the latitude range 50 °< phi < 90°N enabling the imaging of large scale perturbations in the auroral zone.

         Coverage on 11 November 2001, 2:00 UT