A1 Refereed original research article in a scientific journal
Magnetosheath jet properties and evolution as determined by a global hybrid-Vlasov simulation
Authors: Palmroth M, Hietala H, Plaschke F, Archer M, Karlsson T, Blanco-Cano X, Sibeck D, Kajdic P, Ganse U, Pfau-Kempf Y, Battarbee M, Turc L
Publisher: COPERNICUS GESELLSCHAFT MBH
Publication year: 2018
Journal: Annales Geophysicae
Journal name in source: ANNALES GEOPHYSICAE
Journal acronym: ANN GEOPHYS-GERMANY
Volume: 36
Issue: 5
First page : 1171
Last page: 1182
Number of pages: 12
ISSN: 0992-7689
DOI: https://doi.org/10.5194/angeo-36-1171-2018
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/35680520
We use a global hybrid-Vlasov simulation for the magnetosphere, Vlasiator, to investigate magnetosheath high-speed jets. Unlike many other hybrid-kinetic simulations, Vlasiator includes an unscaled geomagnetic dipole, indicating that the simulation spatial and temporal dimensions can be given in SI units without scaling. Thus, for the first time, this allows investigating the magnetosheath jet properties and comparing them directly with the observed jets within the Earth's magnetosheath. In the run shown in this paper, the interplanetary magnetic field (IMF) cone angle is 30 degrees, and a foreshock develops upstream of the quasi-parallel magnetosheath. We visually detect a structure with high dynamic pressure propagating from the bow shock through the magnetosheath. The structure is confirmed as a jet using three different criteria, which have been adopted in previous observational studies. We compare these criteria against the simulation results. We find that the magnetosheath jet is an elongated structure extending earthward from the bow shock by similar to 2.6 R-E, while its size perpendicular to the direction of propagation is similar to 0.5 R-E. We also investigate the jet evolution and find that the jet originates due to the interaction of the bow shock with a high-dynamic-pressure structure that reproduces observational features associated with a short, large-amplitude magnetic structure (SLAMS). The simulation shows that magnetosheath jets can develop also under steady IMF, as inferred by observational studies. To our knowledge, this paper therefore shows the first global kinetic simulation of a magnetosheath jet, which is in accordance with three observational jet criteria and is caused by a SLAMS advecting towards the bow shock.
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