Fig. 4

Schematic representations of the variables associated with the MSIS, IRI, and IGRF models used to infer the E-region electric fields. The acronyms used are as follows: ν _in is ion–neutral collision frequency, ν _en is electron–neutral collision frequency, n(O), n(O₂), and n(N₂) are the neutral densities of O, O₂, and N₂, respectively, N _i is ions density, N _e is the electron density, H is the horizontal component of magnetic field B, Ω _i is the ion gyro frequency, Ω _e is the electron gyro frequency, Ψ ₀ is the anisotropic factor. Local Hall (σ _H) and Pedersen (σ _P) conductivities, field-line-integrated Hall (Σ _H) and Pedersen (Σ _P) conductivities, and zonal (Ey) and vertical (Ez) electric field components are placed in the central circle