Current Journal of Applied Science and Technology

This article focuses on determining VTEC and STEC values ​​at any geographic location. This determination is achieved not through satellite data, but via a robust theoretical framework. The method employed involved developing a formula for electron volume density. This density is derived from expressions describing the altitudinal variation of solar radiation power, volume, and the ionization energy of the oxygen atom. The resulting formula was obtained after adjusting the initial formula, which yielded exponential values ​​at 6 AM, 12 PM, 6 PM, and midnight. Thus, for a given geographic location, the formula provides the VTEC and STEC values, as well as their diurnal variability curves. The VTEC/STEC modeling reveals the following key aspects: (1) For a given longitude, the variability of VTEC/STEC with latitude highlights the inverse fountain effect at 6 AM and 6 PM, with amplitudes decreasing with distance from the equator at latitudes of 10°N,S to 20°N,S. At other times of day, the amplitudes increase from the equator to the North and South Poles, where the observed VTEC/STEC values ​​are exponential. (2) For a given latitude, the modeling based on longitude provides diverse profiles. (3) Also, if the vertical drift velocity is varied via the production factor, the following observations are made: (a) The higher the drift velocity or production factor, the lower the VTEC/STEC values. (b) The lower these factors are, the higher the VTEC/STEC values. Other applications include, firstly, the development of formulas for modeling critical frequencies and electric current density. Secondly, the introduction of another form of VTEC, STEC, whose unit is the TECU, equal to 10¹⁶ electrons per meter. Finally, future research will focus on polar electron jets, scintillations, electric and magnetic fields, and the magnetosphere.