Three‐dimensional interaction of interplanetary shock waves with the bow shock and magnetopause: A comparison of theory with ISEE observations

Abstract

The propagation of shock waves in the solar wind and their three‐dimensional interaction with the terrestrial bow shock, magnetosheath, and magnetopause is examined theoretically and compared with observations made by the ISEE spacecraft. First the formulae underlying the new position and orientation of the bow shock front after the interaction are given. Then magnetic field and plasma data from the ISEE 1, 2, and 3 spacecraft are compared with the theoretical estimates of the propagation time of the shock waves between ISEE 1 and 3. Examination of data obtained on August 18, 1978, when both ISEE 1 and 3 were in the solar wind, show good agreement with theory. Using a simple model of the magnetosheath, we can extend our predictions to include the propagation time through the magnetosheath. Two examples of the interplanetary shock interaction with the magnetosphere while ISEE 1 and 2 were in the outer magnetosphere on August 27 and October 4, 1978, show quite satisfactory agreement with the predictions of this simple model. On August 27, 1978, the magnetopause is blown well past ISEE 1 and 2, and the two spacecraft pass completely through the magnetosheath in 2.5 min. Rapid as this may appear, we show that this behavior is as predicted by the theoretical treatment.

Modification of interplanetary shocks near the bow shock and through the magnetosheath

“…This motion is a result of changes of magnetosheath parameters downstream of the IP shock. These observations are in an agreement with the predictions based on the RankineHugoniot conditions [Grib et al, 1979;Zhuang et al, 1981].…”

“…Using the Rankine-Hugoniot conditions, Dryer et al [1967], Ivanov [1964], Dryer [1973], Shen and Dryer [1972], and Grib et al [1979] have shown that the interaction of the IP shock with the bow shock (which is a fast reversed shock) creates three discontinuities: the fast reverse shock (the original bow shock), fast forward shock (the original IP shock) and a contact discontinuity between these shocks in a one-dimensional hydrodynamic case. A comparison between the 3-D MHD simulations and experimental observations was prepared by Zhuang et al [1981] and the authors concluded that all observed discontinuities moved with velocities corresponding to the Rankine-Hugoniot conditions.…”

“…[5] On the other hand, as Zhuang et al [1981] noted, the propagation of IP shocks within the magnetosheath is propagation through an inhomogeneous medium to the obstacle: the magnetopause. Analysis of the Rankine-Hugoniot conditions [Grib, 1972;Grib et al, 1979;Wu, 2003] shows that the interaction between the fast shock and the magnetopause (defined as a tangential discontinuity) results in a rarefaction wave propagating toward the bow shock.…”

“…Analysis of the Rankine-Hugoniot conditions [Grib, 1972;Grib et al, 1979;Wu, 2003] shows that the interaction between the fast shock and the magnetopause (defined as a tangential discontinuity) results in a rarefaction wave propagating toward the bow shock. The presence of this wave reflected from the magnetopause was indicated by Zhuang et al [1981].…”

Modeling Extreme Compression of the Magnetosphere: Results from a Global MHD Simulation of the May 4, 1998 Event

“…The transmitted shock wave delimiting the region of high Alfven Mach number is between X= -10 and -15 R E , and the bump marking the progression of the compression of the magnetospheric field has moved further tailward, to around X= -20 R E . The dynamics of the shock interaction with the bow shock-magnetopause system seen in the simulation are in agreement with theoretical models [e.g., Grib et al, 1979;Zhuang et al, 1981] and observa tions [Winterhalter et al, 1981]. A detailed analysis com paring our simulation results with those from analytical MHD models will be reported elsewhere.…”