Features of turbulent cascade development in the magnetosheath during ICME

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Abstract
Large-scale disturbances in the interplanetary medium are the main cause of the global perturbations inside Earth’s magnetosphere. Transition region called magnetosheath is known to be located in front of the magnetosphere in which plasma and magnetic field properties, as well as their variations differ significantly from those in the solar wind. Particularly, plasma passage through the magnetosheath has been demonstrated to modify substantially features of the cascade of turbulent fluctuations of the solar wind, with the pattern of the modification being different for quiet and disturbed conditions in the interplanetary medium. In this study, we examine features of turbulent cascade formation in the magnetosheath during interplanetary manifestation of coronal mass ejection (ICME), by analyzing several cases of ICME interactions with the magnetosphere. The analysis is conducted by comparing magnetic field variations measured simultaneously in the solar wind and in the dayside magnetosheath by Wind, Cluster, THEMIS, and MMS spacecraft in 2016–2017. Interaction of ICME with the magnetosphere is shown to cause the least change in the fluctuation power if there is a compression region in front of it; on the opposite, when there is no compression region, the fluctuation power increases considerably. ICMEs that caused significant changes in the Dst index were determined to be accompanied by the least changes in the turbulent cascade in the magnetosheath, whereas the most significant modification of the turbulence features were observed during ICMEs which did not trigger substantial geomagnetic disturbances

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