TY - JOUR

T1 - Magnetotail Configuration During a Steady Convection Event as Observed by Low-Altitude and Magnetospheric Spacecraft

AU - Sergeev, V. A.

AU - Tsyganenko, N. A.

AU - Angelopoulos, V.

AU - Runov, A. V.

AU - Singer, H. J.

PY - 2018/10

Y1 - 2018/10

N2 - Motivated by ongoing discussion regarding the magnetic configuration in the near-Earth and midtail regions and its role in populating the inner magnetosphere during long-duration steady magnetospheric convection (SMC) events, we analyze a rich collection of observations during similar to 10 hr of strong, steady solar wind driving. Auroral boundaries and regions of stretched and dipolarized magnetic field in the plasma sheet were monitored using solar electron loss cone anisotropy observed by low-altitude spacecraft. Following a southward turning of the interplanetary magnetic field and a subsequent 3- to 4-hr period of large-scale substorm-related reconfigurations and plasma injections, the near-Earth magnetic configuration evolved into a nonstandard type, which lasted until the end of this SMC event (5 hr). During that time a dipolarized region with complicated Bz landscape persisted in the midtail, while the configuration was very stretched in the near tail. This was manifested as a highly depressed magnetic Bz component at geostationary orbit and as persistent nonadiabatic electron scattering at the periphery of the outer radiation belt. In addition, in situ observations suggest that a thin current sheet extended longitudinally toward the dawn terminator. In the return convection region near the terminator, observations of this azimuthal current sheet were sporadically interrupted/modulated by earthward convecting plasma structures, either remnants of reconnection-produced plasma bubbles or flapping waves. The hybrid magnetotail configuration (dipolar in the midtail and stretched in the near tail) observed during this long-duration SMC event poses a challenge for empirical magnetospheric modeling.

AB - Motivated by ongoing discussion regarding the magnetic configuration in the near-Earth and midtail regions and its role in populating the inner magnetosphere during long-duration steady magnetospheric convection (SMC) events, we analyze a rich collection of observations during similar to 10 hr of strong, steady solar wind driving. Auroral boundaries and regions of stretched and dipolarized magnetic field in the plasma sheet were monitored using solar electron loss cone anisotropy observed by low-altitude spacecraft. Following a southward turning of the interplanetary magnetic field and a subsequent 3- to 4-hr period of large-scale substorm-related reconfigurations and plasma injections, the near-Earth magnetic configuration evolved into a nonstandard type, which lasted until the end of this SMC event (5 hr). During that time a dipolarized region with complicated Bz landscape persisted in the midtail, while the configuration was very stretched in the near tail. This was manifested as a highly depressed magnetic Bz component at geostationary orbit and as persistent nonadiabatic electron scattering at the periphery of the outer radiation belt. In addition, in situ observations suggest that a thin current sheet extended longitudinally toward the dawn terminator. In the return convection region near the terminator, observations of this azimuthal current sheet were sporadically interrupted/modulated by earthward convecting plasma structures, either remnants of reconnection-produced plasma bubbles or flapping waves. The hybrid magnetotail configuration (dipolar in the midtail and stretched in the near tail) observed during this long-duration SMC event poses a challenge for empirical magnetospheric modeling.

KW - current sheet

KW - magnetotail configuration

KW - particle precipitation

KW - remote sensing

KW - steady convection events

KW - substorms

KW - RECONNECTION

KW - STATE

KW - DRIVEN

KW - PRECIPITATION

KW - SOLAR-WIND

KW - DYNAMICS

KW - MAGNETIC-FIELD

KW - BOUNDARY

KW - SUBSTORMS

KW - PLASMA SHEET

UR - http://www.scopus.com/inward/record.url?scp=85055485594&partnerID=8YFLogxK

U2 - 10.1029/2018JA025867

DO - 10.1029/2018JA025867

M3 - Article

AN - SCOPUS:85055485594

VL - 123

SP - 8390

EP - 8406

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 0148-0227

IS - 10

ER -