Thin filament simulations of oscillatory flow braking in a dipole-tilted magnetotail with ionospheric dissipation

Abstract:

Bursty Bulk Flows (BBFs) induce rapid localized motion in the inner-magnetosphere and are thought to stimulate interchange oscillations in the flux pileup region. Flow braking occurs at the earthward approach of BBF events that lead to Oscillatory Flow Braking (OFB). We interpret OFB as interchange oscillations of a localized magnetic filament displaced from equilibrium. We adopt a model that uses the thin filament approximation to describe the motion of an isolated flux tube in a static background environment. This 1D code can be run with high accuracy and low numerical dissipation compared to 3D MHD codes. The static background is a force balanced 2D configuration that represents the magnetotail with dipole tilt. Previous simulation output shows that motion in the interchange direction is coupled to flapping motion in tilted field line geometries. This suggests that observational signatures of OFB may have many spectral components that will depend on the degree of coupling. In this study, the effect of dissipation due to ionospheric electric fields for the coupled interchange-flapping oscillations will be described and analyzed.