Comparative Analysis of the Vlasiator Simulations and MMS Observations of Multiple X-Line Reconnection and Flux Transfer Events

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Akhavan-Tafti , M , Palmroth , M , Slavin , J A , Battarbee , M , Ganse , U , Grandin , M , Le , G , Gershman , D J , Eastwood , J P & Stawarz , J E 2020 , ' Comparative Analysis of the Vlasiator Simulations and MMS Observations of Multiple X-Line Reconnection and Flux Transfer Events ' , Journal of geophysical research. Space physics , vol. 125 , no. 7 , ARTN e2019JA027410 . https://doi.org/10.1029/2019JA027410

Title: Comparative Analysis of the Vlasiator Simulations and MMS Observations of Multiple X-Line Reconnection and Flux Transfer Events
Author: Akhavan-Tafti, M.; Palmroth, M.; Slavin, J. A.; Battarbee, M.; Ganse, U.; Grandin, M.; Le, G.; Gershman, D. J.; Eastwood, J. P.; Stawarz, J. E.
Other contributor: University of Helsinki, Department of Physics
University of Helsinki, Space Physics Research Group
University of Helsinki, Department of Physics
University of Helsinki, Particle Physics and Astrophysics


Date: 2020-07
Language: eng
Number of pages: 22
Belongs to series: Journal of geophysical research. Space physics
ISSN: 2169-9380
DOI: https://doi.org/10.1029/2019JA027410
URI: http://hdl.handle.net/10138/319023
Abstract: The Vlasiator hybrid-Vlasov code was developed to investigate global magnetospheric dynamics at ion-kinetic scales. Here we focus on the role of magnetic reconnection in the formation and evolution of magnetic islands at the low-latitude magnetopause, under southward interplanetary magnetic field conditions. The simulation results indicate that (1) the magnetic reconnection ion kinetics, including the Earthward pointing Larmor electric field on the magnetospheric side of an X-point and anisotropic ion distributions, are well-captured by Vlasiator, thus enabling the study of reconnection-driven magnetic island evolution processes, (2) magnetic islands evolve due to continuous reconnection at adjacent X-points, "coalescence" which refers to the merging of neighboring islands to create a larger island, "erosion" during which an island loses magnetic flux due to reconnection, and "division" which involves the splitting of an island into smaller islands, and (3) continuous reconnection at adjacent X-points is the dominant source of magnetic flux and plasma to the outer layers of magnetic islands resulting in cross-sectional growth rates up to + 0.3 R-E(2)/min. The simulation results are compared to the Magnetospheric Multiscale (MMS) measurements of a chain of ion-scale flux transfer events (FTEs) sandwiched between two dominant X-lines. The MMS measurements similarly reveal (1) anisotropic ion populations and (2) normalized reconnection rate similar to 0.18, in agreement with theory and the Vlasiator predictions. Based on the simulation results and the MMS measurements, it is estimated that the observed ion-scale FTEs may grow Earth-sized within similar to 10 min, which is comparable to the average transport time for FTEs formed in the subsolar region to the high-latitude magnetopause. Future simulations shall revisit reconnection-driven island evolution processes with improved spatial resolutions.
Subject: magnetic reconnection
flux transfer events
Magnetospheric Multiscale Mission
global hybrid-Vlasov Vlasiator simulations
reconnection-driven magnetic island dynamics
FTE evolution
ELECTRON-DIFFUSION REGION
MAGNETIC RECONNECTION
MESSENGER OBSERVATIONS
FIELD
MAGNETOPAUSE
PLASMA
MECHANISM
MOTION
115 Astronomy, Space science
114 Physical sciences
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