Average spatial distributions of oxygen charge states in the global magnetosphere as observed by Polar

Abstract:

Geomagnetically trapped oxygen ions of solar and ionospheric origin have previously been observed in the Earth’s magnetosphere. Early observations from AMPTE/CCE have studied this distribution within a limited spatial range of L-shells over all magnetic local times (MLT). This study expands on these early results using observations from the Polar spacecraft. The distributions by charge state show O⁶⁺, from the solar wind, charge exchanging into O⁵⁺, O⁴⁺, and O³⁺ as the ion populations drift to lower L-shells. Meanwhile, ionospheric O⁺ and O²⁺ are primarily seen at low L-shells and may also play a role in O³⁺ populations. We present here the K_p, B_z, and AE dependencies of oxygen charge states (O⁺ through O⁶⁺) in MLT and L-shell in the magnetosphere of the Earth. The distributions of these charge states provide insight into the injection and energization of both ionospheric oxygen as well as solar wind ions inside the magnetosphere.