The Vlasiator Ionosphere: Coupling an Ionosphere Model to a Global Hybrid-Vlasov Simulation

Abstract:

Vlasiator is a hybrid-Vlasov simulation model employed to represent plasma processes in near-Earth space. Recent simulations have encompassed the whole Earth's magnetosphere domain in 3D at kinetic scales, thus showing that the employed hybrid kinetic Vlasov approach has become computationally viable. This opens new avenues and possibilities in magnetospheric modeling.

However, simulations were constrained in their treatment of inner magnetospheric processes up to now. The simulations' inner boundary model had been formulated to treat Earth as a perfectly conducting sphere, absorbing all infalling plasma and neglecting ionospheric dynamics. While this model proved to be sufficiently precise for the science goals in large-scale magnetospheric dynamics, an update was ultimately required.

Hence, Vlasiator was extended by an ionosphere model, consisting of a method to couple field-aligned currents onto an ionosphere grid, a solver for the ionospheric potential with a semiempirical conductivity tensor, and a mechanism for the resulting electric fields to affect source terms in the magnetospheric inner boundary.

In this presentation, we outline the ionospheric boundary model in Vlasiator and show preliminary results from global simulations, highlighting the interplay between magnetospheric and ionospheric kinetic phenomena.