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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 1 | Copyright
Ann. Geophys., 36, 107-124, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 25 Jan 2018

Regular paper | 25 Jan 2018

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US–CRCM

Natalia Buzulukova1,2, Jerry Goldstein3,4, Mei-Ching Fok1, Alex Glocer1, Phil Valek3,4, David McComas5, Haje Korth6, and Brian Anderson6 Natalia Buzulukova et al.
  • 1NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, Maryland, USA
  • 2University of Maryland, Astronomy Department, GPHI, College Park, Maryland, USA
  • 3University of Texas, San Antonio, Texas, USA
  • 4Southwest Research Institute, Texas, USA
  • 5Princeton Plasma Physics Lab, Princeton University, Princeton, New Jersey, USA
  • 6Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland, USA

Abstract. During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases (dropouts) in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere–ionosphere (M–I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US–CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensification of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open–closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M–I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global model results enable the reconstruction of a more complete system-level picture of the dropout events and provides insight into M–I coupling aspects that have not previously been investigated.

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Short summary
The paper presents a case study of Earth's magnetosphere dynamics during the geomagnetic storm of 14–16 November 2012. We use a recently developed global model of the magnetosphere that combines a 3-D magnetohydrodynamics model with a kinetic bounce-averaged model for a representation of the energetic ring current population (1–200 keV). We use the model together with multipoint measurements to understand the observations and provide insight into magnetosphere–ionosphere coupling aspects.
The paper presents a case study of Earth's magnetosphere dynamics during the geomagnetic storm...