Ionospheric electrical conductances produced by auroral proton precipitation

From incoherent scatter radar observations and space-borne particle detecto r data, it appears that energetic proton precipitation can sometimes, for s ame locations, be a major source of ionization in the auroral ionosphere an d contribute significantly to the electrical conductances. Here we propose a simple parameterization for the Pedersen and Hall conductances produced b y proton precipitation. The derivation is based on a proton transport code for computing the electron production rate and on an effective recombinatio n coefficient for deducing the electron density. The atmospheric neutral de nsities and temperatures and the geomagnetic-field strength are obtained fr om standard models. The incident protons are assumed to have a Maxwellian d istribution in energy with a mean energy < E > in the 2-40 keV range and an energy flux Q(0). The parameterized Pedersen and Hall conductances are fun ctions of < E > and Q(0), as well as of the geomagnetic-field strength. The dependence on these quantities is compared with those obtained for electro n precipitation and for solar EUV radiation. To add the contribution of pro ton precipitation to the total conductances for electrodynamic studies in a uroral regions, the conductances produced by electron and proton precipitat ions can be combined by applying a root-sum-square approximation.