Mapping of foF2 over Europe based on GPS-derived TEC data

GPS observations of the European Permanent Network (EPN) were used to study the possibility of evaluating foF2 parameter based on TEC data. The slab thickness parameter (τ) served as a factor to convert the TEC to foF2. The TEC data over Europe were obtained from TEC maps. While creating TEC maps, the GPS measurements of EPN network were used. The dense network of GPS stations in Europe (about 100 permanent stations with the average distance between stations: 150–200 km) provided high spatial and temporal resolution of TEC maps and of the foF2 derived from these. The time resolution of TEC maps is about 5 min.For simplification, only the value of τ was used to obtain foF2 during the period of 1996–2003. There was good agreement between GPS-derived TEC data and measured foF2 for quiet and moderate geomagnetic conditions. The RMS of foF2 obtained from TEC data and measurements reached 1.0–1.5 MHz for all middle-latitude European ionosonde stations in October 2003.