O.A. Maltseva - Dr. Sc. (Phys.-Math.), Research Scientist, Research Institute of Physics SFU (Rostov-on-Don). E-mail: mal@ip.rsu.ru N.S. Moshaeva - Part-programming engineer, JSC «OKTB «Vektor». E-mail: mozh_75@mail.ru T.N. Nikitenko - Junior Research Scientist, Research Institute of Physics SFU (Rostov-on-Don). E-mail: niki-ta@mail.ru

Generalization and addition of a series of papers of the authors devoted to usage of the total electron content ТЕС for calculation of the critical frequency foF2, defining propagation conditions of radio-waves in the ionosphere is given. The leading role is played by the experimental median of the equivalent slab thickness of the ionosphere τ(med). The main attention is paid to its usage during disturbed conditions. Defined according to more than 40 stations in April 2014, relative variations δfoF2 and δТЕС showed that disturbance was global with various force in various regions, however synchronism of variations was preserved everywhere, that is why, the parameter τ(med) is a reliable coefficient for ТЕС up to moderate disturbances (Dst > −80 nT). Correspondence with the experimental values of foF2 is increased in comparison with the IRI model in limits about 1,5 to 4 with average value 2,2 on all globe. The question on a choice of a global model of τ(med) is considered. Different models prove to be useful in different situations, but there are still problems in foF2 modeling in southern hemisphere.

 

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