The Dynamics of Plasmaspheric Oxygen Ions: Global Imaging and In Situ Sampling
Abstract
Oxygen-rich ion structures such as the warm plasma cloak and the cold dense oxygen (O+) torus are known only from statistical analysis of in situ data. Observing the time-dependent global dynamics of plasmaspheric O+ is most directly accomplished by global imaging. Microscale physics is revealed by species-separated ion measurements such as are currently provided by the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) instrument. In this paper we investigate the potential for cross-scale measurement of the dense O+ torus using both imaging and simultaneous in situ data. We demonstrate the feasibility of extreme ultraviolet (EUV) imaging of the plasmaspheric dense O+ torus, using simple core plasma density models and a simulated image code. EUV imaging will reveal essential features of the dense oxygen torus: its formation, its latitudinal/local time extent, and possibly its origin as a dayside ionospheric upflow. Complementing this system-level approach, detailed analysis of in situ oxygen ion pitch angle distributions (PADs) reveals important details about ion transport and pathways for oxygen ions to enter the inner magnetosphere. Statistical analyses of density, temperature, and PADs suggest that O+ ions enter via a process other than simple refilling. A case study using HOPE data illustrates the PAD analysis method and points the way toward future comprehensive investigation of plasmaspheric O+ ions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSM23A..10G
- Keywords:
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- 2724 Magnetopause and boundary layers;
- MAGNETOSPHERIC PHYSICSDE: 2728 Magnetosheath;
- MAGNETOSPHERIC PHYSICSDE: 7526 Magnetic reconnection;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7835 Magnetic reconnection;
- SPACE PLASMA PHYSICS