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- Title
Embedded Regions 1 and 2 Field-Aligned Currents: Newly Recognized From Low-Altitude Spacecraft Observations.
- Authors
Jiang Liu; Lyons, L. R.; Chih-Ping Wang; Yuzhang Ma; Strangeway, R. J.; Yongliang Zhang; Kivelson, M.; Ying Zou; Khurana, K.
- Abstract
Regions 1 and 2 (R1 and R2) field-aligned currents (FACs), manifestations of large-scale convection in Earth's magnetosphere-ionosphere (M-I) system, often contain intense FAC layers of mesoscale latitudinal width near the R1/R2 interface. We refer to such layers as "embedded" R1 and R2 FACs. Likely resulting from enhanced magnetosphere-ionosphere (M-I) convection, these FACs may indicate M-I configuration change and contribute significantly to substorm current wedges. We present several events in which embedded FACs were observed by low-altitude spacecraft in the ionosphere. All the events occurred during active geomagnetic conditions or a substorm growth phase, and most map to an equatorial location on the nightside. When an embedded FAC is upward, it coincides with inverted-V electron precipitation and a discrete auroral arc. If an upward embedded FAC is in the postmidnight-to-dawn sector, a dawnside auroral polarization stream appears immediately poleward of it, so it may be important for ionospheric heating, M-I convection, and instabilities. Our results establish embedded FACs as a frequently appearing, fundamental phenomenon for understanding and modeling the magnetosphere-ionosphere system.
- Subjects
MAGNETOSPHERE; IONOSPHERE; CONVECTION (Meteorology); ELECTRON precipitation; GEOMAGNETISM
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 6, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2021JA029207