EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

High-speed Magnetosheath Jet Generation due to Shock Reformation

Savvas Raptis1, Tomas Karlsson1, Andris Vaivads1, Craig Pollock2, Ferdinand Plaschke3, Andreas Johlander4, Henriette Trollvik1, and Per-Arne Lindqvist1
Savvas Raptis et al.
  • 1KTH, Royal Institute of Technology, School of Electrical Engineering and Computer Science., Department of Space and Plasma Physics, Stockholm, Sweden (
  • 2Denali Scientific, Fairbanks, AK, 99709, USA
  • 3Institute of Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Germany
  • 4Swedish institute of Space Physics, Uppsala, Sweden

Magnetosheath jets are transient localized structures of enhanced dynamic pressure observed downstream of the Earth’s bow shock. They may exhibit an increase of velocity reaching solar wind levels, while their density is typically much higher than typical magnetosheath and solar wind values. Jets have been associated to several magnetospheric effects such as, magnetopause reconnection, excitations of surface eigenmodes and even direct plasma penetration in the magnetosphere. While their exact origin is unknown, many mechanisms have been proposed. One of the most prominent explanations involves the interaction of solar wind with local inclinations of the bow shock (ripples) while others include solar wind discontinuities, and foreshock structures.

In this work, by using Magnetosphere Multiscale (MMS) we show in-situ observations of a super-magnetosonic magnetosheath jet being generated as a direct result of the bow shock reformation cycle. The observed jet origin appears to be the result of the dynamical evolution of the shock and the emergence of a spatially de-attached compressive magnetic structure that acts as a local shock front. Due to this, the solar wind particles are effectively transferred downstream without experiencing a strong interaction with the shock, which allows compressed high velocity plasma to be observed downstream of the bow shock.

The proposed mechanism does not require external phenomena (e.g., solar wind discontinuities) or specific configuration of the bow shock (e.g., ripples) to take place. On the contrary, it allows the magnetosheath jet phenomenon to directly originate from the dynamical evolution of the quasi-parallel collisionless shock.

How to cite: Raptis, S., Karlsson, T., Vaivads, A., Pollock, C., Plaschke, F., Johlander, A., Trollvik, H., and Lindqvist, P.-A.: High-speed Magnetosheath Jet Generation due to Shock Reformation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2750,, 2022.

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