Regional mapping of F2 peak plasma frequency by spherical harmonic expansion Original Research Article

We use spherical harmonic analysis to obtain a 2-D map for the critical frequency of the F2 layer in two selected sectors; American and Europe⧹Africa within the area (15°S to 70°N latitude and 120°W to 55°E longitude). Basic data are monthly median foF2 values obtained in the global network of ionospheric stations. Additionally, we compare our results for a few locations with those observed by INTERCOSMOS-19 topside sounder satellite and with the CCIR numerical maps, for different solar activity levels and seasons. It is shown that our monthly median regional maps are preferable to use of the world-wide CCIR numerical maps.