Variation of ionospheric slab thickness over South Africa

Ionospheric slab thickness is defined as the ratio of TEC to maximum electron density of the F-region (NmF2), proportional to the square of the F2-layer critical frequency (foF2). It is an important parameter in that it is linearly correlated with scale height of the ionosphere, which is related to electron density profile. It also reflects variation of the neutral temperature. Therefore, ionospheric slab thickness is a significant parameter representative of the ionosphere. In this paper, the International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network were combined within their own limitations to develop a map of foF2 values for the South African region. This parameter and vertical TEC values derived from the map using the IRI model were used to compute ionospheric slab thickness. Finally climatology of the slab thickness is described by diurnal and seasonal variations.