A causal relationship between midlatitude magnetosheath energetic ions and bow shock magnetic geometry was previously established for ion energy up to 200 keV e−1 for the May 4, 1998, storm event. This study demonstrates that magnetosheath ions with energies above 200 keV up to 1 MeV simply extend the ion spectrum to form a power law tail. Results of cross-correlation analysis suggest that these ions also come directly from the quasi-parallel bow shock, not the magnetosphere. This is confirmed by a comparison of energetic ion fluxes simultaneously measured in the magnetosheath and at the quasi-parallel bow shock when both regions are likely connected by the magnetic field lines. We suggest that ions are accelerated at the quasi-parallel bow shock to energies as high as 1 MeV and subsequently transported into the magnetosheath during this event.
Journal of Geophysical Research: Space Physics
American Geophysical Union
Digital Object Identifier (DOI)
Chang, S.-W., J. D. Scudder, K. Kudela, H. E. Spence, J. F. Fennell, R. P. Lepping, R. P. Lin, and C. T. Russell (2001), MeV magnetosheath ions energized at the bow shock, J. Geophys. Res.,106(A9), 19101–19115, doi:10.1029/2000JA003037.
Copyright 2001 by the American Geophysical Union.