Open AccessDynamic motion of the bow shock and the magnetopause observed by THEMIS spacecraft
Author(s) -
Zhang H.,
Zong Q.G.,
Sibeck D. G.,
Fritz T. A.,
McFadden J. P.,
Glassmeier K.H.,
Larson D.
Publication year - 2009
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008ja013488
Subject(s) - magnetopause , bow shock (aerodynamics) , physics , discontinuity (linguistics) , geophysics , shock (circulatory) , solar wind , shock wave , magnetosheath , interplanetary magnetic field , magnetosphere , bow wave , interplanetary spaceflight , magnetic field , mechanics , medicine , mathematical analysis , mathematics , quantum mechanics
We present an observational study of the dynamic motion of the bow shock and the magnetopause and suggest that the dynamic motion of the bow shock is due to the interaction of an interplanetary shock with the Earth's bow shock. THEMIS B spacecraft crossed the magnetopause, a discontinuity and the bow shock successively in 5 min during its outbound journey on 10 July 2007. Following THEMIS B, THEMIS C, D, E and A consecutively crossed the magnetopause and the discontinuity but not the bow shock. Timing analysis shows that the magnetopause and the discontinuity were moving earthward with speeds of ∼47 km/s and ∼90 km/s, respectively. There is a trend that the discontinuity decelerates as it propagates toward the magnetopause. We suggest that the dynamic motion and the discontinuity are results of the interaction of a weak ( M A = 1.4) interplanetary shock with the Earth's bow shock. After the interaction, the transmitted interplanetary shock took the form of a discontinuity where total magnetic field and density increase and the temperature decreases. The rotation of the magnetic field across this discontinuity was similar to that of the interplanetary shock. The expected fast shock ahead of the discontinuity for shock‐shock interaction was not observed.