Low-frequency variations of the ion flux in the magnetosheath

The paper presents a statistical study of INTERBALL-1 ion flux fluctuations in the magnetosheath. We concentrated on low-frequency variations and their changes from the magnetopause up to the bow shock region. The study is based on relative standard deviations of one minute data computed over 30-min intervals and thus it reveals properties of the fluctuations with periods ranging from units to tens of minutes. The results provide no evidence for any amplification of the solar wind variations in the magnetosheath. The level of magnetosheath fluctuations increases from the bow shock toward the magnetopause. The direction of the interplanetary magnetic field orders fluctuation levels in both the dawn and dusk flanks of the magnetosheath. A significantly higher level of variations is observed in the dawn magnetosheath. The difference is caused by the predominantly Parker spiral orientation of the upstream magnetic field.