Slow mode transition in the frontside magnetosheath

Three magnetosheath passes with density enhancements in front of the magnetopause are studied with data from ISEE 1,2, and 3. The density structure appears to be locally generated and slow mode in nature. In one pass when ISEE 1 and 2 were well separated, the motion of the density structure can be determined. The density structure appears to stand in the magnetosheath flow. Thus it propagates upstream in the rest frame of the flow. The flow in and near the density structure appears to be closer to isothermal than adiabatic. The flow velocity decreases from super-slow to being close to the intermediate and slow mode velocities at the outer edge of the density structure. This study provides additional evidence that the density structure in front of the magnetopause is a slow mode transition in which the flow velocity decreases to the MHD slow mode velocity. The slow mode transition may consist of two waves fronts and a region with strong slow mode waves. This slow mode transition may play an important role in establishing the flow and field pattern near the magnetopause.

[1]  D. Baker,et al.  Lion roars and nonoscillatory drift mirror waves in the magnetosheath , 1982 .

[2]  Michelle F. Thomsen,et al.  Observations of the density profile in the magnetosheath near the stagnation streamline , 1990 .

[3]  C. Russell,et al.  Magnetic field compression at the dayside magnetopause , 1982 .

[4]  C. Russell,et al.  Solar and interplanetary control of the location of the Venus bow shock , 1988 .

[5]  A. Hasegawa,et al.  Kinetic theory of geomagnetic pulsations 1. Internal excitations by energetic particles , 1991 .

[6]  A. Kantrowitz,et al.  MHD CHARACTERISTICS AND SHOCK WAVES. , 1964 .

[7]  G. Siscoe,et al.  A mechanism for pressure anisotropy and mirror instability in the dayside magnetosheath , 1977 .

[8]  G. Siscoe,et al.  Persistent pressure anisotropy in the subsonic magnetosheath region , 1976 .

[9]  C. Russell,et al.  The ISEE 1 and 2 Fluxgate Magnetometers , 1978, IEEE Transactions on Geoscience Electronics.

[10]  H. Rosenbauer,et al.  ISEE-1 and ISEE-2 Fast Plasma Experiment and the ISEE-1 Solar Wind Experiment , 1978, IEEE Transactions on Geoscience Electronics.

[11]  David J. Southwood,et al.  On the form of the flow in the magnetosheath , 1992 .

[12]  G. Siscoe Solar System Magnetohydrodynamics , 1983 .

[13]  J. Horng,et al.  Physical structure of hydromagnetic disturbances in the inner magnetosheath , 1971 .

[14]  L. Lees Interaction between the solar plasma wind and the geomagnetic cavity , 1964 .

[15]  D. Hunten,et al.  Depletion of solar wind plasma near a planetary boundary , 1976 .

[16]  G. S. Stiles,et al.  Observations of plasma depletion in the magnetosheath at the dayside magnetopause , 1979 .

[17]  B. Sonnerup Transport Mechanisms at the Magnetopause , 1980 .

[18]  A. Wolfe,et al.  Large‐amplitude hydromagnetic waves in the inner magnetosheath , 1970 .

[19]  J. Midgley,et al.  Calculation by a moment technique of the perturbation of the geomagnetic field by the solar wind , 1963 .

[20]  A. Summers,et al.  Hydromagnetic flow around the magnetosphere , 1966 .

[21]  Lou‐Chuang Lee,et al.  A study of slow‐mode structures in the dayside magnetosheath , 1991 .

[22]  J. Scudder,et al.  Fast and optimal solution to the 'Rankine-Hugoniot problem'. [for geometrical shock wave properties, conservation constants and self-consistent asymptotic magnetofluid variables of interplanetary medium] , 1986 .

[23]  J. Chao,et al.  Observation of slow shocks in interplanetary space , 1970 .

[24]  Vladimir S. Semenov,et al.  Magnetic field reconnection theory and the solar wind — Magnetosphere interaction: A review , 1985 .