A model of the ionosphere in the altitude interval 50 to 4000 km. Part 2: Molecular ions (N2(+), NO(+), O2(+)) and electron density

Empirical models of molecular ion densities (N2(+), NO(+), O2(+)) and the electron density (Ne) are presented in the altitude interval 50 to 4000 km as functions of time (diurnal, annual), space (position, altitude) and solar flux (F10.7). Using observations of 6 satellites (AE-C, AE-D, AE-E, ALOUETTE-2, ISIS-1, ISIS-2), 4 incoherent scatter stations and more than 700 D-region profiles, this model describes the global gross features of the ionosphere for quiet geophysical conditions. The molecular ion densities and the electron density increase with increasing altitude up to a maximum (or several maxima) and decrease from thereon with increasing height. Between 80 and 200 km, the main ionic constituents are NO(+) and O2(+); below 80 km cluster ions predominate. During local summer conditions the molecular ions and Ne increase around polar latitudes and decrease correspondingly during local winter. The diurnal variations are intrinsically coupled to the individual plasma layers; molecular ion and electron densities are enhanced during daytime and depleted during nighttime.