Abstract
The poleward boundary intensification (PBI) is a common appearance at the poleward boundary of the auroral bulge and auroral oval. The PBI presented here occurred during the expansion phase of a small substorm with an auroral surge power of 6.5 GW. The auroral power of the PBI (1.1 GW) was ~17% of this value. The largest powers above the nominal auroral acceleration region at 5 RE geocentric were carried by Alfvén waves (1.7 GW) and Alfvénic electrons (0.7 GW), sufficient to account for the conjugate PBI auroral power. In contrast, the conjugate quasistatic, field-aligned current power (<0.3 GW) was not sufficient. Observed correlation between quasiperiodic Alfvénic pulses and auroral modulations strengthens our conclusion that the electromagnetic magnetosphere-ionosphere coupling of the PBI was dominantly Alfvénic, as opposed to electrostatic, thus causing Alfvénic aurora.
Original language | English (US) |
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Article number | e2020JA028041 |
Journal | Journal of Geophysical Research: Space Physics |
Volume | 125 |
Issue number | 8 |
DOIs | |
State | Published - Aug 1 2020 |
Bibliographical note
Funding Information:This research was supported by the NSF Grant AGS‐1613134.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
Keywords
- Alfvén wave
- ULF wave
- aurora
- energy transfer
- magnetosphere-ionosphere coupling
- substorm