Energetic proton fluxes within the magnetosheath and upstream from the bowshock: Interball-1 data

The extensive data set of DOK2 energetic proton measurements indicates the decrease of flux at 22-29 keV within the magnetosheath with the distance fr om the magnetopause. It is consistent with the expectations that the main s ource of medium energy magnetosheath ions is the magnetosphere. In the regi on upstream from the bow shock the signatures expected for the preferential acceleration of protons at quasiparallel shocks are found in the survey da ta too. Thus in addition to the proton leakage from the magnetosphere obser ved by several experiments, especially in the case studies by multipoint me asurements or during the increased geomagnetic activity periods, the influe nce of bow shock acceleration to the population of medium energy ions in ne ar upstream region is not negligible. To clarify the contributions of the t wo processes the combination of statistical studies and those based on two point measurements are required in the future.