EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

On the Speed of Interplanetary Shocks Propagating through the Magnetosheath

Clément Moissard1,2, Axel Bernal2, Philippe Savoini1, Dominique Fontaine1, Ronan Modolo3, Vincent David1, and Bayane Michotte de Welle1
Clément Moissard et al.
  • 1Laboratoire de Physique des Plasmas (LPP), Ecole Polytechnique, France
  • 2York Plasma Institute (YPI), University of York, United Kingdom
  • 3Laboratoire atmosphères, milieux, observations spatiales (LATMOS), Sorbonne Université, France

Interplanetary shocks are some of the main drivers of geomagnetic storms. Before they can impact the geomagnetic environment, they propagate through the magnetosheath where their properties and geometry can be modified. What is the velocity of interplanetary shocks propagating through the magnetosheath? Previous numerical simulations and observations have given a wide range of apparently contradictory answers to this question, but they seem to all agree that interplanetary shocks generally slow down as they enter the magnetosheath: the interplanetary shocks’ velocity in the magnetosheath have been reported to be between 0.25 and 0.93 times their velocity in the solar wind. In this work, we offer two competing simple models to predict the propagation velocity of shocks through the magnetosheath. These models are applied to a list of shocks detected by currently operational spacecraft (e.g. Wind, MMS) as well as to results obtained from a hybrid PIC simulation. We show that our models both reconcile previous results and imply that interplanetary shocks could - in certain space weather-relevant situations - travel faster in the magnetosheath than they did in the solar wind. 

How to cite: Moissard, C., Bernal, A., Savoini, P., Fontaine, D., Modolo, R., David, V., and Michotte de Welle, B.: On the Speed of Interplanetary Shocks Propagating through the Magnetosheath, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9423,, 2023.