Simulation of ionospheric parameters for September 2017

Modeling the parameters of the ionosphere is an important part of the process of studying the influence of space weather factors. This paper is devoted to modeling three parameters of the ionosphere (critical frequency foF2, total electron content TEC, and equivalent slab thickness τ) related to the possibility of determining foF2 on a global scale using TEC. Comparison of the model τ(IRI), τ(IRI-Plas) adapted to the observational TEC, τ(NSTM) with the observational median τ(med) for four ionosondes along the 30° E meridian in September 2017 showed the best fit for the IRI-Plas model. Using a polynomial approximation of τ(med) and the distribution of TEC along this meridian in the range of 30° N-70° N, the features of the response of TEC and foF2 to disturbances in September 2017 were revealed. The results for September 7-8, which showed positive enhancements of TEC and foF2, coincide with the results of other researchers. The similarity of this response with the response to the disturbance on September 27-28, which is not associated with a solar flare, is revealed. It is shown that the unique enhancement on September 11 during the magnetic storm recovery phase, identified in the Asian-Australian sector (Lei et al., 2018), is not observed at the 30° E meridian. The global longitudinal distributions of TEC at latitudes of 50° and 30° showed the locality of this phenomenon.