Empirical models of height integrated conductivities

Abstract

Two‐dimensional distributions of the height‐integrated Pedersen and Hall conductivities have been computed for latitudes poleward of 60° invariant representative of two activity levels: 0 ≤K p ≤3 0 and 3 0 <K p ≤9+. Average precipitating fluxes of electrons with energies of 0.15, 1.27, 9.65, and >22 keV obtained by the energetic particle detector of Isis 2 during 1971–1974 are used as input to a Rees‐type computation. The assumption of equilibrium conditions and a recombination rate profile permit calculation of electron density profiles and conductivity profiles. Calculations are performed at 300 grid points, specifically 12 local times and 25 latitudes from 60° to 84° invariant latitude. The models include ionization due to galactic EUV and other background sources that produces base conductivities (Σ P ∼0.1, Σ H ∼0.2 mhos) as well as solar photon ionization through an empirical fit to Chatanika radar observations [Mehta, 1979]. Substantial modulation of the conductivities is found to result from longitudinal variation of the magnitude of the earth's magnetic field. The results show considerable spatial gradients and are expected to be of use in numerical modeling.