Magnetosheath Investigations: Interball Contribution to the Topic

Abstract

We review the statistical processing of four years of INTERBALL-1 observations in the nightside magnetosheath and discuss peculiarities of the magnetosheath ion flux and magnetic field radial profiles. Our investigations reveal that the magnetosheath ion flux profile is similar to but flatter than that predicted by the gasdynamic and MHD models. The most pronounced difference seen at the bow shock region is attributed to kinetic processes not involved in these models. On the other hand, the magnetic field magnitude profile is nearly constant. It indicates that magnetic forces contribute significantly to the formation of the magnetosheath flow and frozen-in approximation should be used with a care. According to our investigations, the rise of the ion flux from the magnetopause toward the bow shock is much steeper during intervals of a radial IMF orientation.Statistical processing has shown (1) the limitations of gasdynamic and MHD models, (2) the conditions favorable for the creation of a plasma depletion layer adjacent to the flank magnetopause, (3) a strong dawn-dusk asymmetry of the ion fluxes, (4) that the presence of high-energy particles influences the total ion flux only weakly, and (5) that the coupling between high-energy particles and the ion flux and/or magnetic field fluctuation level is strong.