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Mesoscale Structures in Earth's Magnetotail Observed Using Energetic Neutral Atom Imaging
A M Keesee1,2, N Buzulukova3,4, C Mouikis2
1Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA.
Geophysical Research Letters
|May 31, 2021
Summary
Mesoscale structures in Earth's magnetotail, observed using energetic neutral atom (ENA) data, are linked to particle transport during space weather events. These structures show increased ion temperatures and correlate with substorm features.
Area of Science:
- Space Physics
- Plasma Physics
- Geophysics
Background:
- Mesoscale structures in Earth's magnetotail are crucial for particle transport into the inner magnetosphere.
- Energetic neutral atom (ENA) imaging offers a global, remote sensing method to observe magnetospheric phenomena.
Purpose of the Study:
- To demonstrate the observation of magnetotail mesoscale structures using ENA data.
- To associate these structures with particle dynamics and substorm activity.
- To validate observations with magnetohydrodynamics simulations.
Main Methods:
- Analysis of energetic neutral atom (ENA) data from the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS).
- Correlation of ENA-derived ion temperature maps with in-situ measurements from Magnetospheric MultiScale (MMS) and Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE).
- Magnetohydrodynamics (MHD) simulations of the observed magnetotail event.
Main Results:
- Localized regions of increased ion temperatures were identified in TWINS ENA data.
- These regions coincided with dipolarization fronts, bursty ion flows (MMS), and field-aligned currents (AMPERE) indicative of substorm activity.
- MHD simulations reproduced key features but showed less intense plasma heating than observed.
Conclusions:
- ENA data is effective for observing magnetotail mesoscale structures and their role in particle transport.
- The study highlights the connection between ENA-observed ion heating, dipolarization fronts, and substorm phenomena.
- Discrepancies in plasma heating intensity suggest potential gaps in current MHD models for substorm processes.
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