On calculating ionospheric conductances from the flux and energy of precipitating electrons

TLDR

Auroral conductances are typically estimated from the energy flux and average energy of precipitating electrons, assuming they behave like Maxwellian distributions, though confusion arises because a Maxwellian’s average energy is twice its characteristic energy. The authors aim to provide revised expressions that link height‑integrated Hall and Pedersen conductances to the flux and average energy of a Maxwellian distribution. They derive these expressions and demonstrate their application using Hilat satellite measurements over Greenland. The method’s accuracy depends on the energy bounds used for integration, and conductances from common auroral spectra closely match those of a Maxwellian with equivalent flux and average energy.

Abstract

Auroral zone conductances can be estimated from the energy flux and average energy of precipitating electrons. These estimates are based on the assumption that the conductances produced by the electrons are very similar to those produced by electrons with Maxwellian energy distributions having the same energy flux and average energy. There has been some confusion in the application of this method because for a Maxwellian the average energy is twice the characteristic energy or temperature. We present revised expressions that relate height‐integrated Hall and Pedersen conductance to the flux and average energy of a Maxwellian. We show that the accuracy of this method depends on the minimum and maximum energy within which the distribution is integrated to get the energy flux and average energy. We also confirm that the conductances produced by some of the more common auroral spectral distributions are similar to those produced by a Maxwellian with the same average energy and energy flux. The application of these results is demonstrated using precipitating electron measurements made by the Hilat satellite during a pass over Greenland.