Magnetospheric response to solar wind dynamic pressure variations: Interaction of interplanetary tangential discontinuities with the bow shock
- and others
Some magnetic impulse events observed in the polar region are related to vortices associated with plasma convection in the ionosphere. Recent analyses of satellite and ground data suggest that the interaction of solar wind dynamic pressure pulses and the magnetosphere may lead to the formation of velocity vortices in the magnetopause boundary layer region. This can in turn lead to the presence of vortices in the polar ionosphere. However, before reaching the Earth`s magnetopause, these interplanetary pressure pulses must interact with and pass through the bow shock. A variation of the solar wind dynamic pressure ({Delta}{rho}V{sup 2}) may be associated with shocks, magnetic holes, or tangential discontinuities (TDs) in the interplanetary medium. The authors study the interaction of interplanetary TDs with the Earth`s bow shock (BS) using both theoretical analysis and MHD computer simulations. It is found that as a result of the collision between a TD and the BS, the jump in the solar wind dynamic pressure associated with the TD is significantly modified, the bow shock moves, and a new fast shock or fast rarefaction wave, which propagates in the downstream direction, is excited. Their theoretical analysis shows that the change in the plasma density across the interplanetary TD plays the most important role in the collision process. A fast compressional shock is excited ahead of the transmitted TD and propagates toward the Earth`s magnetosphere. For the case in which the dynamic pressure is reduced behind the interplanetary TD, the pressure jump across the transmitted TD is substantially weakened, the bow shock moves in the sunward direction, and a rarefaction wave which propagates downstream is excited. The authors also simulate and discuss the interaction of a pair of tangential discontinuities, which may correspond to a magnetic hole, with the BS. 45 refs., 12 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 183239
- Journal Information:
- Journal of Geophysical Research, Vol. 98, Issue A12; Other Information: PBD: 1 Dec 1993
- Country of Publication:
- United States
- Language:
- English
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