Ion temperature in the outer ionosphere — first version of a global empirical model

Abstract

The data set of the ion temperature ( T i) recently derived from the retarding potential analyzer (RPA) volt ampere characteristics measured during the ACTIVE mission (Intercosmos 24, perigee 500 km, apogee 2500 km, inclination 83°, time period 1989–1993) was used to study the global distribution of T i at solar maximum. The first version of a global empirical model has been constructed for altitude levels of 550, 900, and 1500 km, local time and ±90° latitude. At these fixed altitudes T; was represented by a system of associated Legendre polynomials (up to the 6th order) in terms of magnetic local time and latitude coordinates. Comparison of the model values with IRI (International Reference Ionosphere) shows a good agreement at the altitude of 550 km. Above 1000 km IRI shows higher T i values during the day and lower T i during the night. Behavior of model ion and electron temperatures is discussed.