EGU23-2460, updated on 22 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tracking the Subsolar Bow Shock and Magnetopause 

David Sibeck1 and Marcos Silveira2
David Sibeck and Marcos Silveira
  • 1NASA/GSFC, Code 670, Greenbelt, MD, United States of America (
  • 2Catholic University of America, Washington, DC 20064 (

Global magnetohydrodynamic models predict that plasma velocities vary almost linearly from 0 km s-1 at the stationary subsolar magnetopause to ~0.25 VSW at the subsolar bow shock, where VSW is the solar wind velocity.  We show how two-point measurements of the plasma velocity  within ~15° of the Sun-Earth line can be used to determine gradients in the plasma velocity and consequently the time-dependent location of both the subsolar magnetopause and the subsolar bow shock.  A case study employing multiple simultaneous THEMIS spacecraft observations confirms that velocity gradients in the subsolar magnetosheath are linear, except when spacecraft observe rapid fluctuations downstream from the quasi-parallel bow shock.  The method may be useful to those binning magnetosheath observations to develop empirical models, those seeking to determine whether reconnection and hence magnetopause erosion are steady or bursty, and those determining the stand-off distance of the bow shock (or equivalently the polytropic index in the solar wind).

How to cite: Sibeck, D. and Silveira, M.: Tracking the Subsolar Bow Shock and Magnetopause , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2460,, 2023.