ANALYTIC MODEL OF AURORALLY COUPLED MAGNETOSPHERIC AND IONOSPHERIC ELECTROSTATIC POTENTIALS

This paper describes modest but significant improvements on earlier st udies of electrostatic potential structure in the auroral region, usin g the adiabatic auroral arc model. This model has crucial nonlineariti es (connected, for example, with aurorally produced ionization) which have hampered analysis; earlier work has either been linear, which I w ill show is a poor approximation or, if nonlinear, either numerical or too specialized to study parametric dependencies. With certain simpli fying assumptions I find new analytic nonlinear solutions fully exhibi ting the parametric dependence of potentials on magnetospheric (e.g., cross-tail potential) and ionospheric (e.g., recombination rate) param eters. No purely phenomenological parameters are introduced. The resul ts are in reasonable agreement with observed average auroral potential drops. inverted-V scale sizes, and dissipation rates. The dissipation rate is quite comparable to tail energization and transport rates and should have a major effect on tail and magnetospheric dynamics. This paper gives various relations between the cross-tail potential and aur oral parameters (e.g., total parallel currents and potential drops) wh ich can be studied with existing data sets.