Variations of the magnetosheath ion flux and geomagnetic activity

Abstract

The magnetosheath plays a dominant role in the Sun–Earth connection because the magnetosheath field and plasma actually interact with the magnetosphere. The interactions change the magnetospheric magnetic field from its nominal value through a long chain of different processes. The change is usually described by geomagnetic indices and thus it can be expected that these indices would reflect changes in the magnetosheath. The present paper analyzes the relation between geomagnetic activity characterized by changes of the K p, D ST and AE indices and ion flux measured in the night-side magnetosheath. The results suggest a weak dependence of the D ST index on the ion flux in the inner magnetosheath that is connected with a magnetopause displacement. On the other hand, fluctuations of the ion flux in the analyzed frequency range do not correlate with any of the indices.