The Fate of O+ Ions Observed in the Plasma Mantle: Particle Tracing Modelling and Cluster Observations

Abstract:

The atmospheric evolution on geological timescales is partly given by the atmospheric escape. This escape includes ion escape and particularly O⁺ ions. How much O⁺ ions escape from the Earth is the main focus of this study. Using the Tsyganenko and Weimer models to represent the magnetic and electric fields respectively, we traced 26200 O⁺ ions trajectories forward in time and studied their final positions in the Earth’s environment. Starting in the plasma mantle, the initial positions, thermal and parallel bulk velocities of O⁺ ions are taken from the European Cluster observations between 2001 and 2007. Most (98%) of the ions observed in the plasma mantle escape the Earth’s magnetosphere, with 20% of them directly through the dayside magnetopause. An interesting feature of the 80% escaping ions left is that very few reach the distant tail, they rather escape through the nightside magnetopause. Finally, no significant correlation was found between magnetospheric disturbed conditions and the final positions of the traced O⁺ ions.