Determining when GPS gives false positioning due to Space Weather consequences has been one of the aims in a study done by Team Nina 2002 during the Alpbach Summer School. For that, TEC maps (Total Electron Contents of the Earth atmosphere at a certain position) must be derived because the precision is invert proportional to the number of particles along the line of sight for satellites. These maps are sensible to the fluctuations day/night but also particles injections coming from the solar corona via Coronal Mass Ejections (CMEs) or Coronal Holes (CHs). Also a 3D prevision of which structures could erupt toward the magnetosphere are needed for these aspects of Space Weather. © 2006 Springer.