Dual-Spacecraft Studies of EMIC Wave Occurrence using the Van Allen Probes
Abstract
The dual-spacecraft Van Allen Probes mission provides opportunities to overcome some of the spatial-temporal ambiguity of single-spacecraft observations of wave events in Earth's magnetosphere. Because of the slightly different elliptical orbits of the two spacecraft, they lap each other on a time scale of a few months, with spatial scales ranging from 0.1 to 5 RE. In this study we analyze several intervals of EMIC wave activity observed by these spacecraft, as well as simultaneous variations in ring current fluxes and cold plasma. Two-dimensional velocity distributions provide qualitative evidence of local temperature anisotropies in the ring current during times waves were observed, and instability calculations using the WHAMP (waves in homogeneous anisotropic magnetized plasma) code are used to verify local instability. As was found in a recent study by Tetrick et al. [2016], unstable ring current fluxes are essential for EMIC wave onset, but the presence of enhanced levels or gradients of cold plasma density may or may not be necessary.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSM13C..06E
- Keywords:
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- 2768 Plasmasphere;
- MAGNETOSPHERIC PHYSICSDE: 2772 Plasma waves and instabilities;
- MAGNETOSPHERIC PHYSICSDE: 2774 Radiation belts;
- MAGNETOSPHERIC PHYSICSDE: 2778 Ring current;
- MAGNETOSPHERIC PHYSICS