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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 3 | Copyright
Ann. Geophys., 36, 695-703, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 03 May 2018

Regular paper | 03 May 2018

Plasma flow patterns in and around magnetosheath jets

Ferdinand Plaschke1,2 and Heli Hietala3 Ferdinand Plaschke and Heli Hietala
  • 1Institute of Physics, University of Graz, Graz, Austria
  • 2Space Research Institute, Austrian Academy of Sciences, Graz, Austria
  • 3Department of Earth, Planetary, and Space Sciences, University of California Los Angeles, Los Angeles, CA, USA

Abstract. The magnetosheath is commonly permeated by localized high-speed jets downstream of the quasi-parallel bow shock. These jets are much faster than the ambient magnetosheath plasma, thus raising the question of how that latter plasma reacts to incoming jets. We have performed a statistical analysis based on 662 cases of one THEMIS spacecraft observing a jet and another (second) THEMIS spacecraft providing context observations of nearby plasma to uncover the flow patterns in and around jets. The following results are found: along the jet's path, slower plasma is accelerated and pushed aside ahead of the fastest core jet plasma. Behind the jet core, plasma flows into the path to fill the wake. This evasive plasma motion affects the ambient magnetosheath, close to the jet's path. Diverging and converging plasma flows ahead and behind the jet are complemented by plasma flows opposite to the jet's propagation direction, in the vicinity of the jet. This vortical plasma motion results in a deceleration of ambient plasma when a jet passes nearby.

Publications Copernicus
Short summary
Fast jets of solar wind particles drive through a slower environment in the magnetosheath, located sunward of the region dominated by the Earth’s magnetic field. THEMIS multi-spacecraft observations show that jets push ambient particles out of their way. These particles flow around the faster jets into the jets’ wake. Thereby, jets stir the magnetosheath, changing the properties of this key region whose particles and magnetic fields can directly interact with the Earth’s magnetic field.
Fast jets of solar wind particles drive through a slower environment in the magnetosheath,...