Magnetic cloud-bow shock interaction: WIND and IMP-8 observations

R. P. Lepping, A. Szabo, K. W. Ogilvie, R. J. Fitzenreiter, A. J. Lazarus, and J. T. Steinberg

Laboratory for Extraterrestrial Physics, NASA-Goddard Space Flight Center, Greenbelt, MD 20771


An interplanetary magnetic cloud of typical magnetic field flux rope structure and of diameter 0.23 AU was observed in WIND magnetic field and plasma data of February 8, 1995. Starting at about 1 hour later it was also observed at IMP-8, where the bow shock reached at least 39 RE from Earth, on the dusk side, for brief periods within the cloud. This expanded bow shock changed from a perpendicular to pulsation type at IMP-8 as a result of the magnetic field smoothly changing direction within the passing cloud, and its surface normal was nearly, and unexpectedly, invariant during the expansion. It is inferred that, within measurement error, the bow shock's shape expanded almost 'isotropicly' and that the magnetosheath became unusually wide.

Geophys. Res. Lett., 23, 1195-1198, 1996