Bow shock positions and motions on October 18-19, 1995: Effects of dynamic pressure and magnetosonic Mach number

S. Mühlbachler, C. J. Farrugia, H. K. Biernat, P. Aber, D. F. Vogl, J. M. Quinn, N. V. Erkaev, K. W. Ogilvie, R. P. Lepping, S. Kokubun, and T. Mukai

Institute for Meteorology and Geophysics, University of Graz, Hälbarthgasse 1, Austria


We study bow shock positions as monitored by Geotail during the passage of the interplanetary magnetic cloud on October 18-19, 1995. Geotail made 26 bow shock crossings which fall into three groups while it was nominally in the dawnside magnetosheath approaching the Sun-Earth line. Interplanetary parameters are from the WIND spacecraft. The effects of changes in solar wind dynamic pressure and magnetosonic Mach number are studies for each of the three groups of crossings. Comparison of Geotail positions during the measurements and the predicted bow shock standoff distance after Cairns and Lyon [1995] show good agreement. We were able to separate dynamic pressure effects and Mach number effects on the bow shock standoff distance.

in The Solar Wind - Magnetosphere System 3, edited by J. K. Biernat, C. J. Farrugia, and D. F. Vogl, p. 121, Verlag der Österreichischen Akademie der Wissenschaften, Austria, 2000