Project outline: To produce Total Electron Content (TEC) maps such as that shown in the figure, over the South African region, using the GPS_TEC software, and GPS data from the Trignet network in South Africa. To obtain concurrent TEC values from the 4 ionosondes in South Africa, and to compare the values of TEC at the ionosonde sites with values derived from the TEC-maps. To statistically characterize the differences between the GPS TEC and the Ionosonde TEC.