Embedded Regions 1 and 2 Field-Aligned Currents: Newly Recognized From Low-Altitude Spacecraft Observations.
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| Title: | Embedded Regions 1 and 2 Field-Aligned Currents: Newly Recognized From Low-Altitude Spacecraft Observations. |
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| Authors: | Jiang Liu1,2 jliu@igpp.ucla.edu, Lyons, L. R.2, Chih-Ping Wang2, Yuzhang Ma3, Strangeway, R. J.1, Yongliang Zhang4, Kivelson, M.1, Ying Zou5, Khurana, K.1 |
| Source: | Journal of Geophysical Research. Space Physics. Jun2021, Vol. 126 Issue 6, p1-15. 15p. |
| Subject Terms: | *Ionosphere, *Convection (Meteorology), *Geomagnetism, Magnetosphere, Electron precipitation |
| 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. [ABSTRACT FROM AUTHOR] |
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| Database: | GreenFILE |
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