Energetic Ion variations at near Earth plasma during Substorms events and associated magnetic field Dipolarization using Van Allen Probe observations

Abstract

The Earth’s inner magnetosphere is a very dynamic region with energies spanning from sub-eV cold ions in the plasmasphere to relativistic protons and electrons in the radiation belts with energies up to hundreds of MeV. During a geomagnetic storm, the ring current ion composition in the inner magnetosphere changes considerably. The quiet time ring current consists of mainly protons (H+), while the intense storm time ring current is dominated by oxygen (O+) ions. On the other hand, the phenomenon of magnetospheric Substorms is responsible for the discrete injection of energetic ions at the geosynchronous orbit. In this work, we intend to study the effect of the Substorm on variations of energetic ions H+, He+, and O+ in the inner magnetosphere (a geocentric distance of r < 6.6 Re). Generally, Substorms are accompanied by magnetic field dipolarization. However, not much attention has been given to magnetic field dipolarization at r < 6.6 Re. So, we combinely study the substorm onset events from the year 2017-2019 using the Van Allen Probes observations. We analyze H+, He+, and O+ data from Helium Oxygen Electron flux (HOPE), and magnetic field data from the Electric and Magnetic field instrumentation Suit and Integrated Science (EMFISIS) instrumentation suit on board the satellite. Using this data, we study a good number of Substorm onset events for the energy range of 1eV to 50keV energetic ions. We classify events into different categories based upon the L value at the onset of the Substorm. Our current studies will provide the quantification of the observed energetic ions at different energies and their correlation with different interplanetary parameters. The detailed results with the analysis of the statistically significant number of events and the related mechanisms will be discussed in the meeting.