Magnetosphere-ionosphere coupling at Jupiter: Effect of field-aligned potentials on angular momentum transport

Abstract

We present a time-independent model of Jupiter's rotation-driven aurora based on angular momentum conservation, including the effects of a field-aligned potential (φ∥) and an ionospheric conductivity that is modified by precipitating electrons. We argue that φ∥ arises from a limit to field-aligned current at high latitudes, and hence, we apply a current-voltage relation, which takes into account the low plasma densities at high latitudes. The resulting set of nonlinear equations that govern the behavior of angular momentum transfer is underconstrained and leads to a set of solutions, including those derived in earlier work. We show that solutions with high angular momentum transfer, large radial currents, and small mass transport rates (Ṁ ≤ 1000 kg/s) exist. Our set of solutions can reproduce many of the observed characteristics of Jupiter's main auroral oval, including the energy of the precipitating electrons, the energy flux into the ionosphere, the width of the aurora at the ionosphere, and net radial current across the field for a radial mass transport value of ∼500 kg/s. Copyright 2010 by the American Geophysical Union.