Ionospheric electrical conductances produced by auroral proton precipitation

Abstract

Prom incoherent scatter radar observations and space‐borne particle detector data, it appears that energetic proton precipitation can sometimes, for some locations, be a major source of ionization in the auroral ionosphere and contribute significantly to the electrical conductances. Here we propose a simple parameterization for the Pedersen and Hall conductances produced by proton precipitation. The derivation is based on a proton transport code for computing the electron production rate and on an effective recombination coefficient for deducing the electron density. The atmospheric neutral densities and temperatures and the geomagnetic‐field strength are obtained from standard models. The incident protons are assumed to have a Maxwellian distribution in energy with a mean energy 〈E〉 in the 2–40 keV range and an energy flux Q0. The parameterized Pedersen and Hall conductances are functions of 〈E〉 and Q0, as well as of the geomagnetic‐field strength. The dependence on these quantities is compared with those obtained for electron precipitation and for solar EUV radiation. To add the contribution of proton precipitation to the total conductances for electrodynamic studies in auroral regions, the conductances produced by electron and proton precipitations can be combined by applying a root‐sum‐square approximation.